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Research Progress of Deep-UV NLO Crystals and All-solid-state Deep-UV Coherent Light Sources
WANG Xiao-yang, LIU Li-juan
Accepted Manuscript  doi: 10.3788/CO.2020-0028
Abstract(879) FullText HTML(189)
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All-solid-state deep ultraviolet coherent light sources have important applications in frontier science, high technology and many other fields. An effective and feasible technical approach is to use commercially available visible and near-infrared all-solid-state lasers as the fundamental frequency and light source to generate a deep ultraviolet laser through cascaded frequency conversion using nonlinear optical crystals. This paper reviews the research progress of deep ultraviolet nonlinear optical crystals and all-solid-state deep ultraviolet coherent light sources. Taking KBBF crystals as the representative example, their discovery, crystal growth, corresponding prism-coupled device technology, main optical properties, and ability to generate deep ultraviolet coherent light are each introduced. It was proven that KBBF crystals are excellent nonlinear optical crystals that can achieve deep ultraviolet laser output through direct frequency doubling. The applications of deep ultraviolet coherent light sources based on KBBF crystals and prism-coupled technology are discussed, with special focus given to ultra-high resolution photoelectron spectrometers. Finally, the future direction of the development of deep ultraviolet nonlinear optical crystals and all-solid-state deep ultraviolet laser technology are speculated.
Study of TDLAS Detection of Propylene with Complex Spectral Features
Zhong Li, Song Di, Jiao Yue, Li Han, Li Guolin, Ji Wenhai
Accepted Manuscript  doi: 10.3788/CO.2019-0203
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  Objetive  To fulfill the need of propylene measurement in the olefin production process, the tunable diode laser absorption spectroscopy (TDLAS) was studied to improve the analyzing performance.  Method  Propylene is heavy hydrocarbon with higher molecular weight and complicated structure. The spectral absorption lines overlap, and it has broad absorption base. The spectral features are not well rounded in parameters and have no applicable analytical expression. Thus, a numerical simulation approach using absorbance from spectral database to obtain the optimized design parameters was proposed, which is independent of spectra features. In the simulation, the effect of a wider linewidth laser on the absorbance profile was adopted. Through comparison of simulation result and experimental collection, the TDLAS based propylene analyzing apparatus was developed correspondingly. It has a 1628.5 nm center wavelength broader tuning DFB laser. A differential method was utilized in demodulated spectra acquisition to eliminate the bias voltage. The multivariate linear regression model was employed to address the strong spectral interference from the background components in process analysis.  Result  Based on the simulated field test, the max relative error is 0.55% in 0−10 000 ppm range from the step test. For the long-term test at 2 000 ppm, the standard deviation (1σ) is 9.30 ppm. The best standard deviation is 1.33 ppm at 221.9 second integration time through Allen variance analysis. In the anti-interference test, the max error of 19.17 ppm is demonstrated at 2 000 ppm propylene concentration level while methane and ethylene concentration vary.  Conclusion  Thus, the disadvantage of traditional methods such as gas chromatogram (GC) and soft measurement method is overcome by the modulated absorption spectroscopy. The TDLAS system for heavy hydrocarbon detection with complex spectra features was demonstrated with distinct advantages of high precision, good stability and strong interference suppression through multivariate regression modeling.
Effects of a misaligned photodetector in autocollimators on angle measurements
LUO Jing, ZHANG Xiao-hui, HE Xu, YE Lu, ZHANG Tian-yi
Accepted Manuscript  doi: 10.3788/CO.2019-0207
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As one of the key errors in autocollimators, the mislignment of photodetector is analyzed and modeled carefully in this paper. Effects of a misaligned photodetector, which is in any position and orientation in space with regard to the theoretical image plane of autocollimators, on angle measurements are characterized. It is shown that the angular measurement errors of autocollimators induced by a misaligned photodetector increase with greater measuring range L, larger angle θ being tested and smaller focal length L of the collimating object lens. When f=300 mm, L=100 mm, θ=20″, the angular measurement error caused by a misaligned photodetector is 0.0045″. Effects of each photodetector misalignment error on angle measurements by autocollimators are characterized. The model proposed in this paper is validated. Among all kinds of photodetector misalignment errors, the defocusing error has the greatest influences on autocollimators. Hence, it is critical to choose the imaging objective with longer focal length, reduce the measurement distance, and improve the installation accuracy of photodetector along the axis. The model proposed in this paper helps to systematically obtain the angular measurement errors caused by a misaligned photodetector, which will play a key role in building a better error analysis model for autocollimators.
Design of co-aperture antenna for airborne infrared and synthetic aperture radar
WU Wen-da, ZHANG Bao, HONG Yong-feng, ZHANG Yu Xin
Accepted Manuscript  doi: 10.3788/CO.2019-0160
Abstract(956) FullText HTML(159)
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In order to adapt to the increasingly complex detection environment and detection requirements, airborne detection platforms often integrate multiple detection systems. As an ideal integration method, the common aperture composite not only combines the advantages of various types of detection systems, but also reduces the volume of the total system and reduces the burden on the platform. In this paper, a Cassegrain-type common-aperture antenna of infrared and SAR is calculated and designed. Firstly, the primary mirror is calculated according to the radar design requirements; then the Cassegrain structure is solved by equations consisting of aberration coefficients and aspheric parameters.; then, under the limitation of the front Cassegrain structure, the cold stop parameters and infrared system parameters, the lens parameters of the infrared system is calculated by PW method. The radar antenna has a diameter of 1.22 m and a gain of 40.9 dB. The infrared system has a focal length of −1 000 mm and a full field of view of 0.704°. The obscuration ratio is less than 0.33, and the MTF value is greater than 0.4 in each temperature level at 33 lp/mm. Both meet the requirements for use.
Design of optical antenna for laser communication based on off-axis freeform surface
GU Xi-xi, CUI Zhan-gang, QI Bo
Accepted Manuscript  doi: 10.3788/CO.2019-0157
Abstract(526) FullText HTML(361)
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This paper presents a design form of large-field two-mirror afocal optical antenna based on off-axis freeform surface to improve the working range of space laser communication system and simplify the structure of optical system. The optical antenna adopts an afocal structure without using collimating lens elements, which can greatly simplify the system structure, overcome the problems of the traditional focusing optical antenna such as too large volume and too high power density at the focus under the condition of high power light source. First, based on third-order aberration theory, the aberration-free formula of this class of two-mirror afocal optical antenna is derived, and relative results are analyzed. Then, an afocal optical antenna is designed according to the analyzed results and practical requirements. The effective aperture of the system is 100 mm, the magnification is 5, the range of the wavelength is 500 nm~1 100 nm, the full field of view is 0.6°, the primary mirror is part of the concave paraboloid, the secondary mirror is a freeform surface characterized by XY polynomials, and MATLAB software is used to simulate the freeform surface of the secondary mirror. The design results show that the total field of view wavefront error of the optical system is better than λ/14 (λ=500 nm), the Strehl Ratio is greater than 0.8, the system has higher energy concentration, and the image quality is close to the diffraction limit. The field of view of the freeform surface optical system increased by 26.7% compared with traditional conic surface system. Therefore, this antenna structure has strong practicability and good development prospects in the field of laser communication.
Eigen generalized Jones matrix method
Song Dongsheng, Zheng Yuanlin, Liu Hu, Hu Weixing, Zhang Zhiyun, Chen Xianfeng
Accepted Manuscript  doi: 10.3788/CO.2019-0163
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A differential generalized Jones matrix method (dGJM) was recently introduced by Ortega-Quijano and colleagues to derive the GJM for modelling uniaxial and biaxial crystals with arbitrary orientations in laboratory coordinate system. A little later, we propose an eigen generalized Jones matrix method to simulate the phase and polarization of fully polarized light propagating in an anisotropic crystal when the optical axis orientations and light directions are both arbitrary. Our method is equivalent to that of Ortega-Quijano on the physics principle, but we use a modified mathematical technique. We introduce the eigen generalized Jones matrix in the intrinsic coordinate system to precisely calculate the phase and polarization of the light, which overcomes the limitations of the differential generalized Jones matrix method. The simulation results indicate that our method can be used to calculate the polarization distribution when the light beam and optical axis are both in any directions, even if the light beam has a vortex.
Study on the Binding Mechanism of Cefoxitin Sodium to Lysozyme by Synchronous Fluorescence Spectroscopy
ZHANG Hong-cai, LIU Bao-sheng, CHENG Xu
Accepted Manuscript  doi: 10.3788/CO.2019-0112
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Under simulated physiological conditions (pH=7.40), the interaction between tyrosine (Tyr) residue and tryptophan (Trp) residues in lysozyme (LYSO) and cefoxitin sodium (CFXS) was studied by synchronous fluorescence spectroscopy. The results showed that CFXS quenched the fluorescence of Tyr and Trp residues in LYSO by static quenching, and the number of binding sites n was nearly to 1. At 310K, the fluorescence quenching ratio of CFXS with Trp residues NSFQR(Trp)(60.25%) was higher than that of NSFQR(Tyr)(39.75%), indicating that the binding position was closer to the Trp residue. The Hill coefficient nH was about 1, indicating that the binding of CFXS to Tyr and Trp residues in LYSO did not affect the binding of subsequent ligands to proteins. The drug binding rate of CFXS to Tyr residue in LYSO was 0.19% to 0.13%, and the drug binding rate of Trp residue was 0.23% to 0.14%, respectively. The content of free drug was almost unchanged, the results showed that the combination of Tyr and Trp residues in LYSO and CFXS did not affect the efficacy of the drug. The protein binding rate of Tyr residue was 52.69% to 54.67%, and the protein binding rate of Trp residue was 67.67% to 69.39%, implying the number of free amino acid residues in the protein decreased significantly. The main force type of CFXS-LYSO binding system was hydrophobic interaction. The results of molecular docking showed that there was still hydrogen bond interaction between CFXS and LYSO, and the best binding position was near the active center of LYSO and the combination of the two changed the microenvironment of the amino acid residues at the active center.
Space laser communication network mirror linkage tracking control technology
Wang Jun-yao, Song Yan-song, Tong Shou-feng, Jiang Hui-lin, Dong Yan, Dong Ke-yan, Chang Shuai
Accepted Manuscript  doi: 10.3788/CO.2019-0176
Abstract(798) FullText HTML(637)
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In order to realize the space laser communication networking and improve the energy utilization efficiency of the optical antenna, the mirror linkage tracking control technology is studied. The principle of system composition is expounded, and the mirror linkage tracking control strategy based on single detector multi-actuator is discussed in detail. By analyzing the energy of the laser link, the linkage tracking constraints and error requirements are obtained. A mathematical model of double mirror linkage tracking was established. The servo controller was designed and simulated, and the prototype was built to test the tracking performance. The experimental results show that the system can track the target stably, the tracking target accuracy is better than 83 μrad, the double mirror linkage accuracy is better than 26 μrad, and the received optical power of the system is significantly improved, which lays a foundation for space-to-multiple laser communication link networking.
Uncertainty Analysis in Cross-calibration and Optimization Calculation of Calibration Coefficients
GAO Shuai, LI Yuan, BAI Ting-zhu, ZHANG Yu-xiang, ZHENG Xiao-bing
Accepted Manuscript  doi: 10.3788/CO.2019-0215
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For transmitting the radiance standard of the Chinese under-developing hyperspectral radiance standard in RSB to other satellites, the cross-calibration method was used. The general cross-calibration method uses the ordinary least square method to regress the calibration coefficient by data points after time, spatial, observation geometric and spectral collocation. But the ordinary least square algorithm would reduce the validity of the regressed result because of the quality difference between each data point. An optimized method based on the calculation of uncertainty was proposed. The uncertainty analysis method was used to quantify the uncertainty of radiation standard value for each data point, and weight factors were calculated by uncertainty. The weighted least square method was used to regress the calibration coefficient. Using HYPERION as the radiance standard, calibration coefficients of MODIS 1 to 7 channels were regressed by ordinary least squares method and weighted least squares method respectively The regressed coefficients were compared with the official calibration coefficient. The results show that the calibration coefficients calculated by weighted least squares method are closer to the official coefficients for 1, 2, 4, 5, 6, and 7 channels of MODIS, the maximum relative error reduced around 3~5% and the average relative error decreased about 0.5~1.5% compared with the ordinary least squares method, which indicate that the weighted least squares method proposed in this paper can further improve the calculation accuracy of cross-calibration.
High precision corneal curvature radius measurement system
LI Hua-jian, XIAO Zuo-jiang, ZHAO Yuan-yuan, LIU Ying, WANG Rui-zhi, HE Xiao-ying
Accepted Manuscript  doi: 10.3788/CO.2019-0174
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To achieve accurate alignment of the imaging keratometer along the optical axis and improve the measurement accuracy of corneal curvature, this paper designs a high precision imaging corneal curvature measurement system, so as to study the imaging light source, imaging optical system and interferometry system. By uniform irradiation of the target ring through LED array, it forms a light source; The imaging objective lens adopts a double telephoto lens to enlarge the depth of field, which is conducive to alignment measurement. Meanwhile, the magnification of the imaging objective lens are not affected by the depth of field. By using low coherent interferometry, the distance between the corneal vertex and the measured light source is accurately measured by using the grating ruler to monitor the position of the scanning mirror. In this paper, the stability of the imaging objective magnification and the error of corneal curvature measurement of the system are analyzed, and an experimental prototype is made based on the theory. The designed prototype is used to test the standard corneal simulators, and the measurement accuracy of the system is up to ±0.02 mm, which basically meets the requirements of corneal curvature measurement.
Analysis of the Effect of Lens Shutter on Image Motion in Aerial Camera
Yu Chun-feng, Chen Zhi-chao, Jia Ping, Wang Nai-xiang, Hou Han
Accepted Manuscript  doi: 10.3788/CO.2019-0127
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In order to improve the photographic resolution of aerial remote sensing camera and obtain high-resolution aerial images, besides optical system with high modulation transfer function and high-quality imaging medium, the exposure time of shutter should be controlled correctly to ensure that the detector can obtain appropriate image motion value. Based on the structure and working principle of the lens shutter of an aerial mapping camera, in this paper the matrix relationship between the ground object and the image through coordinate transformation method is established, so as to determine the relationship between the exposure time of the shutter and the image motion value. The image motion value and residual error of the image motion is analyzed by combining the parameters of the camera speed-height ratio and the pixel size. According to the different installation modes of the aerial camera, when the residual error of the image motion value is more than 1/3 pixel size, the image motion compensation (IMC) mechanism is necessary to the imaging system. Thus a theoretical basis for the design of IMC mechanism in aerial camera is provided. The analysis was validated by static test and flight test. The test results showed that the aerial camera clearly image and the spatial resolution of the images reaches 36.8 lp/mm, which meets the requirements of the technical index.
Transmission Spectra Characterization of Long-Period Fiber Grating based on numerical Simulation
ZHU Yu-yu, XI Ya-ru, ZHANG Ya-ni, JIANG Peng, XUE Lu, Xu qiang
Accepted Manuscript  doi: 10.3788/CO.2019-0152
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Based on the coupled-mode theory, the equation the transmission spectrum of long period fiber gratings (LPFGs) was solved by using the transmission matrix method and the relationship between the spectral characteristics of LPFGs and grating parameters (such as grating period, writing length and the depth of refractive index modulation) was simulated. The results show that the resonant wavelength of LPFG presents the red-shifted with increasing of the grating period and refractive index modulation depth, and the higher order mode presents more sensitive. At the same time, the change of the spectral bandwidth mainly depends on the writing length of the grating. The bandwidth become narrows gradually with increasing the length of the grating and the phenomenon of the over-coupling occurs when the grating length is over than 5.2 cm. With the increase of the refractive index modulation depth, the grating has the phenomena of incomplete coupling, complete coupling and over-coupling, and the position of the maximum resonance loss will gradually transfer to the lower order mode. The research results have important reference significance for the theoretical research of long-period fiber gratings and the parameter design in practical applications.
Study on the light intensity and spatial coherence characteristics of laser coherent detection in turbulent atmosphere
REN Jian-ying, SUN Hua-yan, ZHAO Yan-zhong, ZHANG Lai-xian
Accepted Manuscript  doi: 10.3788/CO.2019-0194
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In this paper, the analytic expression of cross spectral density function of target reflected light in laser detection is obtained by using generalized huygens-fresnel principle and Goodman target scattering theory, and the expression of intensity distribution and spatial coherence length of target reflected light is further obtained. The influence of different light source parameters and target reflected light parameters on the intensity distribution and coherent length of the target reflected light is simulated by using the expressions obtained in this paper under the conditions of turbulent atmosphere. The results show that: The coherence length of the light source has little effect on the normalized light intensity distribution; The larger the beam waist radius and the reflected light radius, the smaller the coherence length of the received light, and the slower the coherence length increases as the transmission distance increases. In the process of weak turbulent atmospheric transmission, the influence of light source parameters on the received light dominates. The larger the beam waist radius, the smaller the received light intensity and coherence length value. In the process of strong turbulent atmospheric transmission, the influence of atmospheric turbulence on the received light is dominant.
On-line detection of soluble solids content of apples from different origins by visible and near-infrared spectroscopy
LIU Yan-de, XU Hai, SUN Xu-dong, JIANG Xiao-gang, RAO Yu, XU Jia, WANG Jun-zheng
Accepted Manuscript  doi: 10.3788/CO.2019-0128
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In order to realize fast on-line non-destructive testing of soluble solids content (SSC) of apples from different origins, and reduce the effect of origin variability on NIR model, a universal model for predicting soluble solids content of apples from different origins is established. First, the diffuse transmission spectra of Fuji apples from Qixia, Luochuan and Huining are collected by the fruit dynamic online detection equipment. Then 58 characteristic variables are selected and a UVE-PLS universal model for predicting SSC of apples is established using partial least squares algorithm (PLS) combined with uninformative variable elimination (UVE). The root mean square errors of single-origin prediction sets and a total-origin prediction set were 0.50~0.74°Brix and 0.63°Brix, respectively, which increase by 23.2~44.4% and 35.7% respectively compared with the original individual model. Finally, a new external sample set is used to assess the performance of the model, which result in residual prediction deviation of 2.33 and the predicted values within the error range of ±1.0°Brix and ±1.5°Brix of 85% and 100%, respectively. Experimental results indicate that the establishment of a universal model for on-line detection of SSC of apples including multiple origins can improve the robustness of predicting SSC of the samples from other origins, and the appropriate wavelength screening method can simplify the model. The development of a common model for the internal quality of fruit from different origins has a good potential application in wavelength-limited spectroscopy equipment.
Diffraction Characteristics Analysis of Multi-depth Phase Modulation Grating in Terahertz Band
YANG Qiu-jie, HE Zhi-ping, MI Zhong-liang
Accepted Manuscript  doi: 10.3788/CO.2019-0147
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To meet the requirements of terahertz spectral imaging for wide spectral range, high efficiency and real-time detection of spectrometers, a Multi-depth Phase Modulation Grating (MPMG) in terahertz band is proposed. The phase modulation of incident light is realized by introducing optical path difference into the change of groove depth, so that different regions of reflecting terahertz wave front have different phase information. Based on the analysis of the intensity distribution of the diffraction field of the MPMG, the influence of grating parameters on the distribution of the diffraction field is discussed. The diffraction characteristics of the MPMG are verified by experiments. A good agreement is found between the measurements of the 0th- and ±1st-order diffraction efficiency at 0.5 and 0.34 THz and the simulation. It suggests that 0order diffraction of the MPMG has the ability of splitting light.
A High Precision Image Angular Displacement Measurement Device with Adaptive Installation
Yu Hai, Wan Qiuhua, Sun Ying, Lu Xinran, Jia Xingdan
Accepted Manuscript  doi: 10.3788/CO.2019-0107
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The angular displacement measurement technology based on image detector is a hot research to realize high precision and high resolution angular displacement measurement. In order to improve the robustness of the angular displacement measuring device, a high precision image type displacement measuring device with self-adaptive installation is designed in this paper. The installation and adjustment process is very simple, and high resolution and high precision measurement output can be guaranteed in the presence of eccentricity in the calibration grating. Firstly, the principle of angle measuring device based on dual linear image sensors is proposed, and a single-ring absolute grating is designed. Then, the high resolution subdivision algorithm based on centroid algorithm is used to subdivide, and the angle measurement error is compensated by dual linear image sensors. Finally, an experimental device is designed to test the performance of adaptive installation. Experiments show that when the eccentricity of the grating is within ±1 mm, the designed device can achieve high precision and high resolution angular displacement measurement. The device designed in this paper can ensure the output accuracy when the grating has an installation eccentricity of ±1 mm, which lays a foundation for improving the adaptability of small angular displacement measuring device.
Simulation analysis of isolation between laser communication ground test equipments
ZHAO Meng, YAN Chang-xiang, Wu Cong-jun
Accepted Manuscript  doi: 10.3788/CO.2019-0154
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The distance between the laser communication ground test platform and the terminal under test is far less than the actual communication distance due to the space limitation. As a result, the backscattered stray light generated by the test platform optical device will enter the terminal under test, and the signal will seriously affect the terminal under test. Aiming at this problem, this paper puts forward the problem of isolation between the tested terminal and the test platform from the optical interference problem between the tested terminal and the test platform. The Cassegrain and off-axis three-mirror optical antenna are designed respectively. The astigmatism transmission model uses stray light analysis software to analyze the influence of the above two factors on the isolation from the optical antenna structure and surface roughness. The analysis results show that the isolation of the off-axis three-mirror optical antenna is significantly higher than that of the Cassegrain optical antenna, and the isolation increases with the decrease of the optical surface roughness. When the optical surface roughness reaches 0.892 nm, the isolation is −86.22 dB. Finally, the relationship between the ABg model and the Harvey model parameters is derived. According to the roughness and TIS calculation formula, the ABg model parameters with roughness of 0.7 nm and 0.5 nm are theoretically obtained. The isolation between terminals is −94.39 dB and −97.3 dB, achieving an isolation rating of −90 dB.
Fabrication and characterization process of ultra-thin GaN-based LED freestanding membrane
LI Xin, SHA Yuan-qing, JIANG Cheng-wei, WANG Yong-jin
Accepted Manuscript  doi: 10.3788/CO.2019-0192
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In order to deriving the emitting light of LED active layer easily, we study the fabrication process, morphological characterization and optical characterization of LED freestanding membrane. We prepared ultra-thin GaN-based LED freestanding membrane based on GaN-on-silicon wafer by backside process with photolithography, deep reactive ion etching and fast atom beam etching. We found that the deformation of LED freestanding membrane is positively correlated with the diameter of membrane, but negatively correlated with the thickness of membrane by white light interferometer. The deformation is low to nanometer scale, and it is a smooth arch deformation. Through the reflection spectrum test, we found that the number of reflection modes of silicon-based gallium nitride wafers before fabrication is more. The number of reflection modes of LED freestanding membrane is significantly reduced, and the overall light intensity of reflection spectrum is obviously improved. In photoluminescence test, we found that due to the stress release, the spectral peak of LED freestanding membrane has a blue shift of 8.2nm compared with silicon-based gallium nitride wafer. Moreover, LED freestanding membrane with most of epitaxial layer removed has obvious emitting light with backside detection. It demonstrates that LED freestanding membrane is more beneficial to derive the emitted light in photoluminescence test. In this study, LED freestanding membrane with small thickness, large area, small deformation and excellent optical properties has been realized. It provides a new way for the application of GaN-based LED in the field of MOMES.
Algorithm Study of Total Petroleum Hydrocarbons in Contaminated Soils by Three-dimensional Excitation-Emission Matrix Fluorescence Spectroscopy
Gu Yan-hong, Zuo Zhao-lu, Zhang Zhen-zhen, Shi Chao-yi, Gao Xian-he, Lu Jun
Accepted Manuscript  doi: 10.3788/CO.2019-0216
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Assessment of total petroleum hydrocarbons (TPHs) from contaminated soils demands reliable measurement to analyze the types and contents of mixed petroleum hydrocarbons in soils. Three-dimensional excitation-emission matrix (3DEEM) fluorescence spectroscopy technique has been demonstrated as a powerful technology for rapid analyzing the mixed petroleum hydrocarbons by its abundant spectral information. However, the detection precision in soils needs to be improved. This study investigated the correction methods of 3DEEM fluorescence spectra to correct the complicated matrix and scatting effects of soils. To improve the analytical accuracy, parallel factor analysis (PARAFAC) and alternating trilinear decomposition method (ATLD) were used to qualitative and quantitative analyze the mixed petroleum contaminated soils. The methods were used to assess three commonly observed petroleum hydrocarbons: machine oil, lubricating oil, diesel oil, and their mixtures. Compared with the results of PARAFAC, the average recoveries were increased from 85% to 95%, implying that ATLD can distinguish the similar fluorescence spectra well and be more effective in the components and total content detection of petroleum in soils. The present work can lead to the appropriate application of risk assessments and remediation techniques.
Regulation mid-infrared plasmon based on graphene nanoribbons
HAN Jing, GAO Yang, JIAO Weiyan, FAN Guanghua, GAO Ya-chen
Accepted Manuscript  doi: 10.3788/CO.2019-0185
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Graphene supports surface plasmons in the mid-infrared and terahertz regimes. The regulation of surface plasmons in graphene can be achieved by a certain design. In this paper, a resonant tunable structure was designed. By depositing a single layer of graphene ribbons of different widths on a dielectric substrate, discontinuities on the nanoscale were introduced, thereby effectively controlling the interaction of graphene with light. The spectral and electromagnetic field distributions of the structure were theoretical studied using the finite difference time domain method. The results showed that when the designed structure was coupled with the incident light, there would be multiple resonance enhanced absorption peaks. By changing the number, width and distance between the graphene ribbons in each period, the number, position, intensity of the formants can be controlled. In addition, the Fermi energy level of graphene can be changed by applying different bias voltage, so the position and intensity of resonance peak can be adjusted dynamically. Therefore, the structure can regulate graphene plasmon resonance over a wide spectral range. This study provides a theoretical basis for the design of the graphene-based sensor, filter and absorber in infrared regime.
Development of the inverted-cone diversion type heat-stop for solar telescope
ZHANG Yu-chen, WANG Fei-xiang, XU Fang-yu, HUANG Shan-jie, TAN Xu, LU Wen-long, XIAO Jian-guo, JIA Yu-chao, LUO Hong
Accepted Manuscript  doi: 10.3788/CO.2019-0139
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  Objetive  For the large-aperture-size ground-based open-structure solar telescopes, an increase in heat-stop temperature will result in deterioration of image quality. This is one of the many problems facing the CGST(Chinese Giant Solar Telescope) development plan. The heat-stop temperature control problem must be solved in the pre-research stage.  Method  Design a new heat-stop structure, the overall cooling efficiency is high and further strengthened at key locations to achieve uniform temperature control. In particular, the temperature difference at the light-passing hole of the heat-stop has a great influence on the image quality. To this end, ICDT(inverted-cone diversion type) heat-stop design is proposed, which is beneficial to reduce the temperature of the light-passing hole and make The hottest area away from the light-passing hole.  Result  The results of cooling efficiency and heat-stop temperature field simulation show that this scheme is obviously superior to the former. The temperature of ICDT heat-stop is up to 3 ℃ above ambient, which is better than GREGO temperature difference of 7 ℃.The research team also carried out the heat-stop temperature field measurement work and verified the temperature field simulation results.  Conclusion  ICDT heat-stop design has good temperature control capability.
Influence of turbulent atmosphere on the effect of coherent beam combining
SONG Ji-kun, LI Yuan-yang, CHE Dong-bo, GUO Jin, WANG Ting-feng
Accepted Manuscript  doi: 10.3788/CO.2019-0197
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Coherent beam combining is a promising technology for achieving high power laser beam with good beam quality. However, the turbulent atmosphere is one of the key factors that restrict its application and development. This paper focuses on the influence of atmospheric Greenwood frequency on the correction effect of the coherent synthesis system based on stochastic parallel gradient descent (SPGD) algorithm. Firstly, the influence of different turbulence intensities on the correction effect of coherent synthesis systems was analyzed by numerical simulation under static atmospheric conditions. Then, a set of rotating phase screens that meet statistical law of Kolmogorov, are generated by numerical calculation to simulate the turbulent atmosphere, and the correction effect of the coherent combining system with different atmospheric Greenwood frequencies is studied. Finally, experimental investigation on coherent beam combining of two lasers is demonstrated. Simulated and experimental results show that when the system's control algorithm iteration frequency (350 Hz) is constant, as the Greenwood frequency of the atmosphere increases, the disturbance of the phase and light intensity of the beam by the turbulent atmosphere intensifies, making the synthesis effect of the coherent synthesis system worse.
Design and analysis of stress-free clamping of mirror used in free-electron laser beamline
ZHAO Chen-hang, LU Qi-peng, SONG Yuan, GONG Xue-peng, WANG Yi, XU Bin-hao
Accepted Manuscript  doi: 10.3788/CO.2019-0131
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The reflector is an important optical element in the free-electron laser beamline. The deformation error caused by gravity will seriously affects the imaging quality of the beamline. In order to reduce the deformation error, a gravity compensation scheme based on the Bessel point theory is proposed, and a stress-free clamping device is designed. Taking a 440 mm * 50 mm * 50 mm mirror as an example, the deformation error of the mirror with traditional support method is 1.647 μrad. Adopting the device designed above, the results of finite element analysis show that the deformation error reduced to 0.085 7 μrad, which is better than the engineering index 0.1 μrad. To prevent the mirror from moving when switching mode, a small clamping force of no more than 2 N can be added to the mirror, at which point the surface error of the mirror is 0.093 9 μrad. In addition, the dynamic analysis of the device is also carried out, which indicates that the device avoids existing the low natural frequency, this means resonance phenomenon will not rise while using, so the scheme satisfies the requirements of the beamline.
Research on Infrared polarization properties of targets with rough surface
Liu Yi, Shi Hao-dong, Jiang Hui-lin, Li Ying-chao, Wang Chao, Liu Zhang, Li Guan-lin
Accepted Manuscript  doi: 10.3788/CO.2019-0123
Abstract(237) FullText HTML(118)
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Infrared polarization imaging has the advantages of enhancing imaging contrast and distinguishing true-false targets. In order to improve the detection and identification probability, it is necessary to obtain the infrared radiation polarization properties of the targets accurately. However, the traditional analytical model of infrared radiation polarization ignores the shadowing effect caused by rough surfaces. Based on the surface microelement bidirectional reflectance distribution function and by using Muller matrix, the Stocks analytical model of the infrared radiation polarization degree of the rough surface with shadowing function is constructed. The effects of the incident angle and surface roughness on the polarization for the metallic and nonmetallic targets are analyzed quantitatively. The analysis results show that the polarization degree of infrared spontaneous radiation decreases as the increase of roughness in both metal and nonmetal, with the decrease of polarization degree of nonmetallic greater than that of metal. Under the same roughness and same temperature, the polarization degree value of infrared radiation of the metallic is always greater than that of the nonmetal. The polarization degree of infrared radiation increases with the incident angle firstly, and then reaches a peak value within a specific incident angle range. The difference of polarization degree value between the metallic and nonmetallic infrared radiation reaches the maximum within a certain incident angle range. This property is useful to distinguish the metal and nonmetal. Finally, long-wave infrared micro-polarization imaging system and near infrared polarization imaging system are used to collect different scene images. Infrared radiation polarization properties of the targets are basically consistent with the theoretical analysis results. This research is of great significance on analyzing the polarization properties of real targets, designing the infrared polarization system and processing the polarization images.
Optimization and analysis of Primary Mirror for laser incoherent combining system
TANG Wei, LIU Li-sheng, Liu Yang, SHAO Jun-feng, GUO Jin
Accepted Manuscript  doi: 10.3788/CO.2019-0161
Abstract(216) FullText HTML(82)
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Primary mirror used in high power laser incoherent combining system was designed and analyzed. Firstly, the material and the thickness of primary mirror, the supporting way and lightweight scheme of primary mirror were determined theoretically. Then thermal deformation of primary mirror is calculated by the finite element method, and Topology optimization is executed basing on thermal deformation results. Finally, the impact of Gravity factor, base frequency and ambient temperature on primary mirror P-V value was analyzed. The calculation results show that with temperature ΔT and P-V Value of primary mirror irradiated by Six lasers with the power of 10 kW gradually ascend when laser irradiation time is increasing. When laser irradiation time is up to 3 min, temperature ΔT and P-V Value of primary mirror which is not optimized is 83.4 ℃ and 155 nm respectively, and the thermal deformation values in the irradiated area are inconsistent affecting by the structure, the D-value is ablut 1/6 of primary mirror. Lightweight rate of primary mirror after optimizating is 54.5%, thermal deformation value in laser irradiation area is consistent, and P-V value of primary mirror reduce 1/3. Gravity deformation value of primary mirror at different pitching angles is basically the same, and the maximum P-V value was less than 10 nm. The ambient temperature will cause distortion and defocus aberration, and with the increase of ambient temperature, the aberration would be gradually greater. Modal analysis shows that base frequency of the primary mirror meets the system requirement; The conclusions have a reference value for high power laser incoherent combining system.
Deep Infrared Small Target State Sensing Method for Deep Learning
Huang Le-hong, Cao Li-hua, Li Ning, Li Yi
Accepted Manuscript  doi: 10.3788/CO.2019-0120
Abstract(199) FullText HTML(112)
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  Objective  To propose a new depth learning-based discriminant algorithm for the current spatial infrared weak target state perception method with low accuracy, large artificial interference and high data quality requirements.  Methods  Firstly, the phenomenon of spatial infrared weak target state change is analyzed and a special data set is established. Then the convolutional neural network framework dedicated to target state perception task is established, and innovations are made in local annotation and adaptive threshold. Finally, the simulation data generated by the target radiation intensity information collected by the laboratory is used to train and test the algorithm, and the target state perception evaluation index system is established to evaluate the experimental results.  Results  The experimental results show that the accuracy of the discrimination is 98.27% when the continuous complete radiation intensity information is input. When the radiation intensity information of the segment is input, the accuracy of each state is greater than 90%.  Conclusion  This algorithm makes up for the shortcomings of the current method, which is not sensitive to the low false alarm rate and the incomplete target information. It improves the detection speed and accuracy and better satisfies the demand of spatial infrared weak target sensing tasks.
Method of Enhancing the Quality of In-Line Holographic Images for Micro-Milling Tool
CHENG Ya-ya, YU Hua-dong, YU Zhan-jiang, XU Jin-kai, ZHANG Xiang-hui
Accepted Manuscript  doi: 10.3788/CO.2019-0217
Abstract(213) FullText HTML(100)
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In the method of tool-setting based on digital in-line holography, the zero-order image and the defocused twin-image can form a strong and complex background noise, which is superimposed on the real image and seriously reduces the quality of the reconstructed image. Aiming at the interferential images in digital in-line holography, a holographic image enhancement method based on improved self-snake model is proposed. The improved self snake model select the diffusion intensity according to the gradient of the initial image. The experimental results show that, the improved self-snake model can avoid the appearing of jagged edges and “pseudo-contours” which caused by the large gradient background noise during the diffusion process. This improvement made up for the shortcomings of the self-snake model in the applications of holographic image. In addition, Comparing with the phase retrieval approach and multi-plane reproduction approach, the improved self-snake model filtering method proposed in this paper not only has better suppression for interferential images, but also can enhance the edge of the tool, which is conducive to the realization of tool-setting based on digital in-line holography.
Modeling and numerical simulation of semiconductor switching for ultra-short pulse CO2 laser
GAO Yue-juan, CHEN Fei, PAN Qi-kun, YU Hang-hang, LI Hong-chao, TIAN You-peng
Accepted Manuscript  doi: 10.3788/CO.2019-0159
Abstract(1050) FullText HTML(1003)
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The physical dynamics of ultra-short pulse widths CO2 laser output has been studied in semiconductor switching technology. Firstly, based on the analysis of the generation, recombination and diffusion mechanism of laser-produced carriers, we introduce direct absorption, Auger recombination, plasmon-assisted recombination, ambipolar diffusion process and add Drude theory, to improve the theoretical model of semiconductor switching. Secondly, we simulate and analyze the generation of ultra-short CO2 pulses by two-stage semiconductor optical switches using this model. The results show that the model is in good agreement with the experimental results abroad, which shows the rationality and correctness of the model. Finally, the model is used to analyze the effect of control pulse duration on the efficiency of the two-stage switching. It is found that short control pulse is more conducive to intercepting high-quality ultra-short CO2 pulses accurately and efficiently. Semiconductor switching is an effective technique to realize the output of ultra-short CO2 laser with adjustable pulse width.
Research on modification of Soluble Solids Content sorting line based on light source transmitting and receiving integrated probe
Liu Yande, Rao Yu, Sun Xudong, Xiao Huaichun, Jiang Xiaogang, Xu Hai, Li Xiong, Xu Jia, Wang Guantian
Accepted Manuscript  doi: 10.3788/CO.2019-0165
Abstract(551) FullText HTML(776)
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Traditional external quality sorting is now unable to meet the growing demand for quality and taste of the fruit, it has great significance to ensure sugar sorting and the proper taste quality of the fruit by Sugar sorting transformation of traditional external quality sorting line. Near-infrared diffuse reflectance spectroscopy of navel orange has collected under two different detection modes, the spectral energy of diffuse reflection mode of ring is stronger than that diffuse reflection mode of multiple points, and the spectral appearance of these two detection modes are roughly the same. Reduce the effects of stray light and noise by baseline correction, multiple scatter correction, first-order, second-order derivative, etc, of Spectral data preprocessing. Building the partial least squares model of sugar content in two different diffuse reflection detection methods for navel orange and analysis. Experimental results indicate that Optimal use of baseline correction preprocessing methods under two different detection methods; the correlation coefficient of the sugar model is 0.82 at diffuse reflection mode of ring, the root mean square error of predicted is 0.45°Brix; the correlation coefficient of the sugar model is 0.80 at diffuse reflection mode of multiple points, the root mean square error of predicted is 0.48°Brix. The research shows that it is feasible to use PLS modeling combined with near-infrared diffuse reflectance spectroscopy to upgrade the sugar separation line function on the traditional external quality sorting line.
Design of solid-state array laser radar receiving optical system
WEI Yu, JIANG Shi-lei, SUN Guo-bin, ZHANG Xing-xing, WANG Yu-ning
Accepted Manuscript  doi: 10.3788/CO.2019-0166
Abstract(495) FullText HTML(389)
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Under the premise of the safety of solid-state array laser radar, in order to improve the image plane energy uniformity of the optical system and increase the energy received by the optical system, to ensure the detection of low SNR in the process and the exploratory of target. Through giving optical parameters to the modeling of the emitted laser energy and the received energy, studying the factors which affect the image illumination of the receiving optical system and pointing out the design method elements of large-field large relative aperture high illumination uniformity optical system.through the ZEMAX optimization analysis, giving the specific implementation of process. Finally, a laser radar receiving lens with λ=905(±5)nm, focal length of 15 mm, relative aperture of 1/1.4, and a field of view of 2ω=76°. Less than 77 mm, MTF value @20 lp/mm is greater than 0.5, relative distortion of 0.85 field of view is less than 8%, image surface illumination non-uniformity is less than 7.2%.which meet the requirements of lidar detection.
Research on ultra-precision grinding and polishing method of the large-scale Al2O3 ceramic guides
LIU Jian, CAI Li-ming, CHENG Xian-kai, GU Guo-gang, YU Yong
Accepted Manuscript  doi: 10.3788/CO.20191203.0663
Abstract(541) FullText HTML(100)
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In order to improve the ultra-precision polishing efficiency of alumina ceramic guide, the relationship between the polishing parameters, such as polishing pressure, polishing speed and abrasive mixing interval and grinding, and polishing efficiency was analyzed. First of all, the polishing discs and abrasive was selected base on alumina ceramic guide's physical parameters and characteristics. Second, with the high precision plane parallel crystal as the detection tool, the number of stripes between crystal and guide quantitatively the polishing efficiency. At the end, the best processing parameters applied to the alumina ceramic guide was obtained: polishing pressure should be controlled around 40 N; the line speed of polishing should be 45 m/min; grinding agent should be added every 30 min. With the same time period, this set of process parameters will obtain higher surfaceaccuracy.
Fan-shaped mid-infrared chiral metamaterials based on indium tin oxide and their circular dichroism
ZHU Ye-xin, LI Ya-nan, SHI Wei-jie, ZHANG Wen-tao, YAN Chang-chun
Accepted Manuscript  doi: 10.3788/CO.2019-0190
Abstract(227) FullText HTML(124)
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A mid-infrared chiral metamaterial was designed to overcome the problems of the large volume and high cost for the traditional mid-infrared laser polarization state control. The fan-shaped chiral structure made of indium tin oxide (ITO) was designed, and its circular dichroism (CD) characteristics in the mid-infrared band were studied. The CD variation characteristics of the structure were discussed by changing the filling material in the fan blade layer, the thickness of fan blades, the size of fan blades, the number of fan blade, and the material of fan blades. The simulation results show that the CD signal varies with these parameters. When the filling material is silicon and the fan blade is six pieces, the strongest CD signal of 0.052 is obtained near the wavelength of 5.3 μm by selecting the appropriate fan thickness and size. The simulation results also show that compared with the silver and gold, the structure made of ITO exhibits broadband circular dichroism, which provides a new idea for the design of broadband polarization-state control devices in the mid-infrared band.
Articles in press have been peer-reviewed and accepted, which are not yet assigned to volumes /issues, but are citable by Digital Object Identifier (DOI).
Research Progress of Deep-UV NLO Crystals and All-solid-state Deep-UV Coherent Light Sources
WANG Xiao-yang, LIU Li-juan
Accepted Manuscript  doi: 10.3788/CO.2020-0028
Abstract(879) FullText HTML(189)
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All-solid-state deep ultraviolet coherent light sources have important applications in frontier science, high technology and many other fields. An effective and feasible technical approach is to use commercially available visible and near-infrared all-solid-state lasers as the fundamental frequency and light source to generate a deep ultraviolet laser through cascaded frequency conversion using nonlinear optical crystals. This paper reviews the research progress of deep ultraviolet nonlinear optical crystals and all-solid-state deep ultraviolet coherent light sources. Taking KBBF crystals as the representative example, their discovery, crystal growth, corresponding prism-coupled device technology, main optical properties, and ability to generate deep ultraviolet coherent light are each introduced. It was proven that KBBF crystals are excellent nonlinear optical crystals that can achieve deep ultraviolet laser output through direct frequency doubling. The applications of deep ultraviolet coherent light sources based on KBBF crystals and prism-coupled technology are discussed, with special focus given to ultra-high resolution photoelectron spectrometers. Finally, the future direction of the development of deep ultraviolet nonlinear optical crystals and all-solid-state deep ultraviolet laser technology are speculated.
Study of TDLAS Detection of Propylene with Complex Spectral Features
Zhong Li, Song Di, Jiao Yue, Li Han, Li Guolin, Ji Wenhai
Accepted Manuscript  doi: 10.3788/CO.2019-0203
Abstract(1696) FullText HTML(188)
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  Objetive  To fulfill the need of propylene measurement in the olefin production process, the tunable diode laser absorption spectroscopy (TDLAS) was studied to improve the analyzing performance.  Method  Propylene is heavy hydrocarbon with higher molecular weight and complicated structure. The spectral absorption lines overlap, and it has broad absorption base. The spectral features are not well rounded in parameters and have no applicable analytical expression. Thus, a numerical simulation approach using absorbance from spectral database to obtain the optimized design parameters was proposed, which is independent of spectra features. In the simulation, the effect of a wider linewidth laser on the absorbance profile was adopted. Through comparison of simulation result and experimental collection, the TDLAS based propylene analyzing apparatus was developed correspondingly. It has a 1628.5 nm center wavelength broader tuning DFB laser. A differential method was utilized in demodulated spectra acquisition to eliminate the bias voltage. The multivariate linear regression model was employed to address the strong spectral interference from the background components in process analysis.  Result  Based on the simulated field test, the max relative error is 0.55% in 0−10 000 ppm range from the step test. For the long-term test at 2 000 ppm, the standard deviation (1σ) is 9.30 ppm. The best standard deviation is 1.33 ppm at 221.9 second integration time through Allen variance analysis. In the anti-interference test, the max error of 19.17 ppm is demonstrated at 2 000 ppm propylene concentration level while methane and ethylene concentration vary.  Conclusion  Thus, the disadvantage of traditional methods such as gas chromatogram (GC) and soft measurement method is overcome by the modulated absorption spectroscopy. The TDLAS system for heavy hydrocarbon detection with complex spectra features was demonstrated with distinct advantages of high precision, good stability and strong interference suppression through multivariate regression modeling.
Effects of a misaligned photodetector in autocollimators on angle measurements
LUO Jing, ZHANG Xiao-hui, HE Xu, YE Lu, ZHANG Tian-yi
Accepted Manuscript  doi: 10.3788/CO.2019-0207
Abstract(217) FullText HTML(133)
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As one of the key errors in autocollimators, the mislignment of photodetector is analyzed and modeled carefully in this paper. Effects of a misaligned photodetector, which is in any position and orientation in space with regard to the theoretical image plane of autocollimators, on angle measurements are characterized. It is shown that the angular measurement errors of autocollimators induced by a misaligned photodetector increase with greater measuring range L, larger angle θ being tested and smaller focal length L of the collimating object lens. When f=300 mm, L=100 mm, θ=20″, the angular measurement error caused by a misaligned photodetector is 0.0045″. Effects of each photodetector misalignment error on angle measurements by autocollimators are characterized. The model proposed in this paper is validated. Among all kinds of photodetector misalignment errors, the defocusing error has the greatest influences on autocollimators. Hence, it is critical to choose the imaging objective with longer focal length, reduce the measurement distance, and improve the installation accuracy of photodetector along the axis. The model proposed in this paper helps to systematically obtain the angular measurement errors caused by a misaligned photodetector, which will play a key role in building a better error analysis model for autocollimators.
Design of co-aperture antenna for airborne infrared and synthetic aperture radar
WU Wen-da, ZHANG Bao, HONG Yong-feng, ZHANG Yu Xin
Accepted Manuscript  doi: 10.3788/CO.2019-0160
Abstract(956) FullText HTML(159)
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In order to adapt to the increasingly complex detection environment and detection requirements, airborne detection platforms often integrate multiple detection systems. As an ideal integration method, the common aperture composite not only combines the advantages of various types of detection systems, but also reduces the volume of the total system and reduces the burden on the platform. In this paper, a Cassegrain-type common-aperture antenna of infrared and SAR is calculated and designed. Firstly, the primary mirror is calculated according to the radar design requirements; then the Cassegrain structure is solved by equations consisting of aberration coefficients and aspheric parameters.; then, under the limitation of the front Cassegrain structure, the cold stop parameters and infrared system parameters, the lens parameters of the infrared system is calculated by PW method. The radar antenna has a diameter of 1.22 m and a gain of 40.9 dB. The infrared system has a focal length of −1 000 mm and a full field of view of 0.704°. The obscuration ratio is less than 0.33, and the MTF value is greater than 0.4 in each temperature level at 33 lp/mm. Both meet the requirements for use.
Design of optical antenna for laser communication based on off-axis freeform surface
GU Xi-xi, CUI Zhan-gang, QI Bo
Accepted Manuscript  doi: 10.3788/CO.2019-0157
Abstract(526) FullText HTML(361)
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This paper presents a design form of large-field two-mirror afocal optical antenna based on off-axis freeform surface to improve the working range of space laser communication system and simplify the structure of optical system. The optical antenna adopts an afocal structure without using collimating lens elements, which can greatly simplify the system structure, overcome the problems of the traditional focusing optical antenna such as too large volume and too high power density at the focus under the condition of high power light source. First, based on third-order aberration theory, the aberration-free formula of this class of two-mirror afocal optical antenna is derived, and relative results are analyzed. Then, an afocal optical antenna is designed according to the analyzed results and practical requirements. The effective aperture of the system is 100 mm, the magnification is 5, the range of the wavelength is 500 nm~1 100 nm, the full field of view is 0.6°, the primary mirror is part of the concave paraboloid, the secondary mirror is a freeform surface characterized by XY polynomials, and MATLAB software is used to simulate the freeform surface of the secondary mirror. The design results show that the total field of view wavefront error of the optical system is better than λ/14 (λ=500 nm), the Strehl Ratio is greater than 0.8, the system has higher energy concentration, and the image quality is close to the diffraction limit. The field of view of the freeform surface optical system increased by 26.7% compared with traditional conic surface system. Therefore, this antenna structure has strong practicability and good development prospects in the field of laser communication.
Eigen generalized Jones matrix method
Song Dongsheng, Zheng Yuanlin, Liu Hu, Hu Weixing, Zhang Zhiyun, Chen Xianfeng
Accepted Manuscript  doi: 10.3788/CO.2019-0163
Abstract(494) FullText HTML(435)
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A differential generalized Jones matrix method (dGJM) was recently introduced by Ortega-Quijano and colleagues to derive the GJM for modelling uniaxial and biaxial crystals with arbitrary orientations in laboratory coordinate system. A little later, we propose an eigen generalized Jones matrix method to simulate the phase and polarization of fully polarized light propagating in an anisotropic crystal when the optical axis orientations and light directions are both arbitrary. Our method is equivalent to that of Ortega-Quijano on the physics principle, but we use a modified mathematical technique. We introduce the eigen generalized Jones matrix in the intrinsic coordinate system to precisely calculate the phase and polarization of the light, which overcomes the limitations of the differential generalized Jones matrix method. The simulation results indicate that our method can be used to calculate the polarization distribution when the light beam and optical axis are both in any directions, even if the light beam has a vortex.
Study on the Binding Mechanism of Cefoxitin Sodium to Lysozyme by Synchronous Fluorescence Spectroscopy
ZHANG Hong-cai, LIU Bao-sheng, CHENG Xu
Accepted Manuscript  doi: 10.3788/CO.2019-0112
Abstract(367) FullText HTML(132)
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Under simulated physiological conditions (pH=7.40), the interaction between tyrosine (Tyr) residue and tryptophan (Trp) residues in lysozyme (LYSO) and cefoxitin sodium (CFXS) was studied by synchronous fluorescence spectroscopy. The results showed that CFXS quenched the fluorescence of Tyr and Trp residues in LYSO by static quenching, and the number of binding sites n was nearly to 1. At 310K, the fluorescence quenching ratio of CFXS with Trp residues NSFQR(Trp)(60.25%) was higher than that of NSFQR(Tyr)(39.75%), indicating that the binding position was closer to the Trp residue. The Hill coefficient nH was about 1, indicating that the binding of CFXS to Tyr and Trp residues in LYSO did not affect the binding of subsequent ligands to proteins. The drug binding rate of CFXS to Tyr residue in LYSO was 0.19% to 0.13%, and the drug binding rate of Trp residue was 0.23% to 0.14%, respectively. The content of free drug was almost unchanged, the results showed that the combination of Tyr and Trp residues in LYSO and CFXS did not affect the efficacy of the drug. The protein binding rate of Tyr residue was 52.69% to 54.67%, and the protein binding rate of Trp residue was 67.67% to 69.39%, implying the number of free amino acid residues in the protein decreased significantly. The main force type of CFXS-LYSO binding system was hydrophobic interaction. The results of molecular docking showed that there was still hydrogen bond interaction between CFXS and LYSO, and the best binding position was near the active center of LYSO and the combination of the two changed the microenvironment of the amino acid residues at the active center.
Space laser communication network mirror linkage tracking control technology
Wang Jun-yao, Song Yan-song, Tong Shou-feng, Jiang Hui-lin, Dong Yan, Dong Ke-yan, Chang Shuai
Accepted Manuscript  doi: 10.3788/CO.2019-0176
Abstract(798) FullText HTML(637)
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In order to realize the space laser communication networking and improve the energy utilization efficiency of the optical antenna, the mirror linkage tracking control technology is studied. The principle of system composition is expounded, and the mirror linkage tracking control strategy based on single detector multi-actuator is discussed in detail. By analyzing the energy of the laser link, the linkage tracking constraints and error requirements are obtained. A mathematical model of double mirror linkage tracking was established. The servo controller was designed and simulated, and the prototype was built to test the tracking performance. The experimental results show that the system can track the target stably, the tracking target accuracy is better than 83 μrad, the double mirror linkage accuracy is better than 26 μrad, and the received optical power of the system is significantly improved, which lays a foundation for space-to-multiple laser communication link networking.
Uncertainty Analysis in Cross-calibration and Optimization Calculation of Calibration Coefficients
GAO Shuai, LI Yuan, BAI Ting-zhu, ZHANG Yu-xiang, ZHENG Xiao-bing
Accepted Manuscript  doi: 10.3788/CO.2019-0215
Abstract(216) FullText HTML(103)
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For transmitting the radiance standard of the Chinese under-developing hyperspectral radiance standard in RSB to other satellites, the cross-calibration method was used. The general cross-calibration method uses the ordinary least square method to regress the calibration coefficient by data points after time, spatial, observation geometric and spectral collocation. But the ordinary least square algorithm would reduce the validity of the regressed result because of the quality difference between each data point. An optimized method based on the calculation of uncertainty was proposed. The uncertainty analysis method was used to quantify the uncertainty of radiation standard value for each data point, and weight factors were calculated by uncertainty. The weighted least square method was used to regress the calibration coefficient. Using HYPERION as the radiance standard, calibration coefficients of MODIS 1 to 7 channels were regressed by ordinary least squares method and weighted least squares method respectively The regressed coefficients were compared with the official calibration coefficient. The results show that the calibration coefficients calculated by weighted least squares method are closer to the official coefficients for 1, 2, 4, 5, 6, and 7 channels of MODIS, the maximum relative error reduced around 3~5% and the average relative error decreased about 0.5~1.5% compared with the ordinary least squares method, which indicate that the weighted least squares method proposed in this paper can further improve the calculation accuracy of cross-calibration.
High precision corneal curvature radius measurement system
LI Hua-jian, XIAO Zuo-jiang, ZHAO Yuan-yuan, LIU Ying, WANG Rui-zhi, HE Xiao-ying
Accepted Manuscript  doi: 10.3788/CO.2019-0174
Abstract(432) FullText HTML(380)
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To achieve accurate alignment of the imaging keratometer along the optical axis and improve the measurement accuracy of corneal curvature, this paper designs a high precision imaging corneal curvature measurement system, so as to study the imaging light source, imaging optical system and interferometry system. By uniform irradiation of the target ring through LED array, it forms a light source; The imaging objective lens adopts a double telephoto lens to enlarge the depth of field, which is conducive to alignment measurement. Meanwhile, the magnification of the imaging objective lens are not affected by the depth of field. By using low coherent interferometry, the distance between the corneal vertex and the measured light source is accurately measured by using the grating ruler to monitor the position of the scanning mirror. In this paper, the stability of the imaging objective magnification and the error of corneal curvature measurement of the system are analyzed, and an experimental prototype is made based on the theory. The designed prototype is used to test the standard corneal simulators, and the measurement accuracy of the system is up to ±0.02 mm, which basically meets the requirements of corneal curvature measurement.
Analysis of the Effect of Lens Shutter on Image Motion in Aerial Camera
Yu Chun-feng, Chen Zhi-chao, Jia Ping, Wang Nai-xiang, Hou Han
Accepted Manuscript  doi: 10.3788/CO.2019-0127
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In order to improve the photographic resolution of aerial remote sensing camera and obtain high-resolution aerial images, besides optical system with high modulation transfer function and high-quality imaging medium, the exposure time of shutter should be controlled correctly to ensure that the detector can obtain appropriate image motion value. Based on the structure and working principle of the lens shutter of an aerial mapping camera, in this paper the matrix relationship between the ground object and the image through coordinate transformation method is established, so as to determine the relationship between the exposure time of the shutter and the image motion value. The image motion value and residual error of the image motion is analyzed by combining the parameters of the camera speed-height ratio and the pixel size. According to the different installation modes of the aerial camera, when the residual error of the image motion value is more than 1/3 pixel size, the image motion compensation (IMC) mechanism is necessary to the imaging system. Thus a theoretical basis for the design of IMC mechanism in aerial camera is provided. The analysis was validated by static test and flight test. The test results showed that the aerial camera clearly image and the spatial resolution of the images reaches 36.8 lp/mm, which meets the requirements of the technical index.
Transmission Spectra Characterization of Long-Period Fiber Grating based on numerical Simulation
ZHU Yu-yu, XI Ya-ru, ZHANG Ya-ni, JIANG Peng, XUE Lu, Xu qiang
Accepted Manuscript  doi: 10.3788/CO.2019-0152
Abstract(563) FullText HTML(481)
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Based on the coupled-mode theory, the equation the transmission spectrum of long period fiber gratings (LPFGs) was solved by using the transmission matrix method and the relationship between the spectral characteristics of LPFGs and grating parameters (such as grating period, writing length and the depth of refractive index modulation) was simulated. The results show that the resonant wavelength of LPFG presents the red-shifted with increasing of the grating period and refractive index modulation depth, and the higher order mode presents more sensitive. At the same time, the change of the spectral bandwidth mainly depends on the writing length of the grating. The bandwidth become narrows gradually with increasing the length of the grating and the phenomenon of the over-coupling occurs when the grating length is over than 5.2 cm. With the increase of the refractive index modulation depth, the grating has the phenomena of incomplete coupling, complete coupling and over-coupling, and the position of the maximum resonance loss will gradually transfer to the lower order mode. The research results have important reference significance for the theoretical research of long-period fiber gratings and the parameter design in practical applications.
Study on the light intensity and spatial coherence characteristics of laser coherent detection in turbulent atmosphere
REN Jian-ying, SUN Hua-yan, ZHAO Yan-zhong, ZHANG Lai-xian
Accepted Manuscript  doi: 10.3788/CO.2019-0194
Abstract(243) FullText HTML(338)
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In this paper, the analytic expression of cross spectral density function of target reflected light in laser detection is obtained by using generalized huygens-fresnel principle and Goodman target scattering theory, and the expression of intensity distribution and spatial coherence length of target reflected light is further obtained. The influence of different light source parameters and target reflected light parameters on the intensity distribution and coherent length of the target reflected light is simulated by using the expressions obtained in this paper under the conditions of turbulent atmosphere. The results show that: The coherence length of the light source has little effect on the normalized light intensity distribution; The larger the beam waist radius and the reflected light radius, the smaller the coherence length of the received light, and the slower the coherence length increases as the transmission distance increases. In the process of weak turbulent atmospheric transmission, the influence of light source parameters on the received light dominates. The larger the beam waist radius, the smaller the received light intensity and coherence length value. In the process of strong turbulent atmospheric transmission, the influence of atmospheric turbulence on the received light is dominant.
On-line detection of soluble solids content of apples from different origins by visible and near-infrared spectroscopy
LIU Yan-de, XU Hai, SUN Xu-dong, JIANG Xiao-gang, RAO Yu, XU Jia, WANG Jun-zheng
Accepted Manuscript  doi: 10.3788/CO.2019-0128
Abstract(390) FullText HTML(152)
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In order to realize fast on-line non-destructive testing of soluble solids content (SSC) of apples from different origins, and reduce the effect of origin variability on NIR model, a universal model for predicting soluble solids content of apples from different origins is established. First, the diffuse transmission spectra of Fuji apples from Qixia, Luochuan and Huining are collected by the fruit dynamic online detection equipment. Then 58 characteristic variables are selected and a UVE-PLS universal model for predicting SSC of apples is established using partial least squares algorithm (PLS) combined with uninformative variable elimination (UVE). The root mean square errors of single-origin prediction sets and a total-origin prediction set were 0.50~0.74°Brix and 0.63°Brix, respectively, which increase by 23.2~44.4% and 35.7% respectively compared with the original individual model. Finally, a new external sample set is used to assess the performance of the model, which result in residual prediction deviation of 2.33 and the predicted values within the error range of ±1.0°Brix and ±1.5°Brix of 85% and 100%, respectively. Experimental results indicate that the establishment of a universal model for on-line detection of SSC of apples including multiple origins can improve the robustness of predicting SSC of the samples from other origins, and the appropriate wavelength screening method can simplify the model. The development of a common model for the internal quality of fruit from different origins has a good potential application in wavelength-limited spectroscopy equipment.
Diffraction Characteristics Analysis of Multi-depth Phase Modulation Grating in Terahertz Band
YANG Qiu-jie, HE Zhi-ping, MI Zhong-liang
Accepted Manuscript  doi: 10.3788/CO.2019-0147
Abstract(363) FullText HTML(256)
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To meet the requirements of terahertz spectral imaging for wide spectral range, high efficiency and real-time detection of spectrometers, a Multi-depth Phase Modulation Grating (MPMG) in terahertz band is proposed. The phase modulation of incident light is realized by introducing optical path difference into the change of groove depth, so that different regions of reflecting terahertz wave front have different phase information. Based on the analysis of the intensity distribution of the diffraction field of the MPMG, the influence of grating parameters on the distribution of the diffraction field is discussed. The diffraction characteristics of the MPMG are verified by experiments. A good agreement is found between the measurements of the 0th- and ±1st-order diffraction efficiency at 0.5 and 0.34 THz and the simulation. It suggests that 0order diffraction of the MPMG has the ability of splitting light.
A High Precision Image Angular Displacement Measurement Device with Adaptive Installation
Yu Hai, Wan Qiuhua, Sun Ying, Lu Xinran, Jia Xingdan
Accepted Manuscript  doi: 10.3788/CO.2019-0107
Abstract(299) FullText HTML(300)
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The angular displacement measurement technology based on image detector is a hot research to realize high precision and high resolution angular displacement measurement. In order to improve the robustness of the angular displacement measuring device, a high precision image type displacement measuring device with self-adaptive installation is designed in this paper. The installation and adjustment process is very simple, and high resolution and high precision measurement output can be guaranteed in the presence of eccentricity in the calibration grating. Firstly, the principle of angle measuring device based on dual linear image sensors is proposed, and a single-ring absolute grating is designed. Then, the high resolution subdivision algorithm based on centroid algorithm is used to subdivide, and the angle measurement error is compensated by dual linear image sensors. Finally, an experimental device is designed to test the performance of adaptive installation. Experiments show that when the eccentricity of the grating is within ±1 mm, the designed device can achieve high precision and high resolution angular displacement measurement. The device designed in this paper can ensure the output accuracy when the grating has an installation eccentricity of ±1 mm, which lays a foundation for improving the adaptability of small angular displacement measuring device.
Simulation analysis of isolation between laser communication ground test equipments
ZHAO Meng, YAN Chang-xiang, Wu Cong-jun
Accepted Manuscript  doi: 10.3788/CO.2019-0154
Abstract(544) FullText HTML(371)
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The distance between the laser communication ground test platform and the terminal under test is far less than the actual communication distance due to the space limitation. As a result, the backscattered stray light generated by the test platform optical device will enter the terminal under test, and the signal will seriously affect the terminal under test. Aiming at this problem, this paper puts forward the problem of isolation between the tested terminal and the test platform from the optical interference problem between the tested terminal and the test platform. The Cassegrain and off-axis three-mirror optical antenna are designed respectively. The astigmatism transmission model uses stray light analysis software to analyze the influence of the above two factors on the isolation from the optical antenna structure and surface roughness. The analysis results show that the isolation of the off-axis three-mirror optical antenna is significantly higher than that of the Cassegrain optical antenna, and the isolation increases with the decrease of the optical surface roughness. When the optical surface roughness reaches 0.892 nm, the isolation is −86.22 dB. Finally, the relationship between the ABg model and the Harvey model parameters is derived. According to the roughness and TIS calculation formula, the ABg model parameters with roughness of 0.7 nm and 0.5 nm are theoretically obtained. The isolation between terminals is −94.39 dB and −97.3 dB, achieving an isolation rating of −90 dB.
Fabrication and characterization process of ultra-thin GaN-based LED freestanding membrane
LI Xin, SHA Yuan-qing, JIANG Cheng-wei, WANG Yong-jin
Accepted Manuscript  doi: 10.3788/CO.2019-0192
Abstract(220) FullText HTML(118)
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In order to deriving the emitting light of LED active layer easily, we study the fabrication process, morphological characterization and optical characterization of LED freestanding membrane. We prepared ultra-thin GaN-based LED freestanding membrane based on GaN-on-silicon wafer by backside process with photolithography, deep reactive ion etching and fast atom beam etching. We found that the deformation of LED freestanding membrane is positively correlated with the diameter of membrane, but negatively correlated with the thickness of membrane by white light interferometer. The deformation is low to nanometer scale, and it is a smooth arch deformation. Through the reflection spectrum test, we found that the number of reflection modes of silicon-based gallium nitride wafers before fabrication is more. The number of reflection modes of LED freestanding membrane is significantly reduced, and the overall light intensity of reflection spectrum is obviously improved. In photoluminescence test, we found that due to the stress release, the spectral peak of LED freestanding membrane has a blue shift of 8.2nm compared with silicon-based gallium nitride wafer. Moreover, LED freestanding membrane with most of epitaxial layer removed has obvious emitting light with backside detection. It demonstrates that LED freestanding membrane is more beneficial to derive the emitted light in photoluminescence test. In this study, LED freestanding membrane with small thickness, large area, small deformation and excellent optical properties has been realized. It provides a new way for the application of GaN-based LED in the field of MOMES.
Algorithm Study of Total Petroleum Hydrocarbons in Contaminated Soils by Three-dimensional Excitation-Emission Matrix Fluorescence Spectroscopy
Gu Yan-hong, Zuo Zhao-lu, Zhang Zhen-zhen, Shi Chao-yi, Gao Xian-he, Lu Jun
Accepted Manuscript  doi: 10.3788/CO.2019-0216
Abstract(501) FullText HTML(137)
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Assessment of total petroleum hydrocarbons (TPHs) from contaminated soils demands reliable measurement to analyze the types and contents of mixed petroleum hydrocarbons in soils. Three-dimensional excitation-emission matrix (3DEEM) fluorescence spectroscopy technique has been demonstrated as a powerful technology for rapid analyzing the mixed petroleum hydrocarbons by its abundant spectral information. However, the detection precision in soils needs to be improved. This study investigated the correction methods of 3DEEM fluorescence spectra to correct the complicated matrix and scatting effects of soils. To improve the analytical accuracy, parallel factor analysis (PARAFAC) and alternating trilinear decomposition method (ATLD) were used to qualitative and quantitative analyze the mixed petroleum contaminated soils. The methods were used to assess three commonly observed petroleum hydrocarbons: machine oil, lubricating oil, diesel oil, and their mixtures. Compared with the results of PARAFAC, the average recoveries were increased from 85% to 95%, implying that ATLD can distinguish the similar fluorescence spectra well and be more effective in the components and total content detection of petroleum in soils. The present work can lead to the appropriate application of risk assessments and remediation techniques.
Regulation mid-infrared plasmon based on graphene nanoribbons
HAN Jing, GAO Yang, JIAO Weiyan, FAN Guanghua, GAO Ya-chen
Accepted Manuscript  doi: 10.3788/CO.2019-0185
Abstract(247) FullText HTML(191)
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Graphene supports surface plasmons in the mid-infrared and terahertz regimes. The regulation of surface plasmons in graphene can be achieved by a certain design. In this paper, a resonant tunable structure was designed. By depositing a single layer of graphene ribbons of different widths on a dielectric substrate, discontinuities on the nanoscale were introduced, thereby effectively controlling the interaction of graphene with light. The spectral and electromagnetic field distributions of the structure were theoretical studied using the finite difference time domain method. The results showed that when the designed structure was coupled with the incident light, there would be multiple resonance enhanced absorption peaks. By changing the number, width and distance between the graphene ribbons in each period, the number, position, intensity of the formants can be controlled. In addition, the Fermi energy level of graphene can be changed by applying different bias voltage, so the position and intensity of resonance peak can be adjusted dynamically. Therefore, the structure can regulate graphene plasmon resonance over a wide spectral range. This study provides a theoretical basis for the design of the graphene-based sensor, filter and absorber in infrared regime.
Development of the inverted-cone diversion type heat-stop for solar telescope
ZHANG Yu-chen, WANG Fei-xiang, XU Fang-yu, HUANG Shan-jie, TAN Xu, LU Wen-long, XIAO Jian-guo, JIA Yu-chao, LUO Hong
Accepted Manuscript  doi: 10.3788/CO.2019-0139
Abstract(207) FullText HTML(97)
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  Objetive  For the large-aperture-size ground-based open-structure solar telescopes, an increase in heat-stop temperature will result in deterioration of image quality. This is one of the many problems facing the CGST(Chinese Giant Solar Telescope) development plan. The heat-stop temperature control problem must be solved in the pre-research stage.  Method  Design a new heat-stop structure, the overall cooling efficiency is high and further strengthened at key locations to achieve uniform temperature control. In particular, the temperature difference at the light-passing hole of the heat-stop has a great influence on the image quality. To this end, ICDT(inverted-cone diversion type) heat-stop design is proposed, which is beneficial to reduce the temperature of the light-passing hole and make The hottest area away from the light-passing hole.  Result  The results of cooling efficiency and heat-stop temperature field simulation show that this scheme is obviously superior to the former. The temperature of ICDT heat-stop is up to 3 ℃ above ambient, which is better than GREGO temperature difference of 7 ℃.The research team also carried out the heat-stop temperature field measurement work and verified the temperature field simulation results.  Conclusion  ICDT heat-stop design has good temperature control capability.
Influence of turbulent atmosphere on the effect of coherent beam combining
SONG Ji-kun, LI Yuan-yang, CHE Dong-bo, GUO Jin, WANG Ting-feng
Accepted Manuscript  doi: 10.3788/CO.2019-0197
Abstract(599) FullText HTML(566)
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Coherent beam combining is a promising technology for achieving high power laser beam with good beam quality. However, the turbulent atmosphere is one of the key factors that restrict its application and development. This paper focuses on the influence of atmospheric Greenwood frequency on the correction effect of the coherent synthesis system based on stochastic parallel gradient descent (SPGD) algorithm. Firstly, the influence of different turbulence intensities on the correction effect of coherent synthesis systems was analyzed by numerical simulation under static atmospheric conditions. Then, a set of rotating phase screens that meet statistical law of Kolmogorov, are generated by numerical calculation to simulate the turbulent atmosphere, and the correction effect of the coherent combining system with different atmospheric Greenwood frequencies is studied. Finally, experimental investigation on coherent beam combining of two lasers is demonstrated. Simulated and experimental results show that when the system's control algorithm iteration frequency (350 Hz) is constant, as the Greenwood frequency of the atmosphere increases, the disturbance of the phase and light intensity of the beam by the turbulent atmosphere intensifies, making the synthesis effect of the coherent synthesis system worse.
Design and analysis of stress-free clamping of mirror used in free-electron laser beamline
ZHAO Chen-hang, LU Qi-peng, SONG Yuan, GONG Xue-peng, WANG Yi, XU Bin-hao
Accepted Manuscript  doi: 10.3788/CO.2019-0131
Abstract(524) FullText HTML(107)
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The reflector is an important optical element in the free-electron laser beamline. The deformation error caused by gravity will seriously affects the imaging quality of the beamline. In order to reduce the deformation error, a gravity compensation scheme based on the Bessel point theory is proposed, and a stress-free clamping device is designed. Taking a 440 mm * 50 mm * 50 mm mirror as an example, the deformation error of the mirror with traditional support method is 1.647 μrad. Adopting the device designed above, the results of finite element analysis show that the deformation error reduced to 0.085 7 μrad, which is better than the engineering index 0.1 μrad. To prevent the mirror from moving when switching mode, a small clamping force of no more than 2 N can be added to the mirror, at which point the surface error of the mirror is 0.093 9 μrad. In addition, the dynamic analysis of the device is also carried out, which indicates that the device avoids existing the low natural frequency, this means resonance phenomenon will not rise while using, so the scheme satisfies the requirements of the beamline.
Research on Infrared polarization properties of targets with rough surface
Liu Yi, Shi Hao-dong, Jiang Hui-lin, Li Ying-chao, Wang Chao, Liu Zhang, Li Guan-lin
Accepted Manuscript  doi: 10.3788/CO.2019-0123
Abstract(237) FullText HTML(118)
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Infrared polarization imaging has the advantages of enhancing imaging contrast and distinguishing true-false targets. In order to improve the detection and identification probability, it is necessary to obtain the infrared radiation polarization properties of the targets accurately. However, the traditional analytical model of infrared radiation polarization ignores the shadowing effect caused by rough surfaces. Based on the surface microelement bidirectional reflectance distribution function and by using Muller matrix, the Stocks analytical model of the infrared radiation polarization degree of the rough surface with shadowing function is constructed. The effects of the incident angle and surface roughness on the polarization for the metallic and nonmetallic targets are analyzed quantitatively. The analysis results show that the polarization degree of infrared spontaneous radiation decreases as the increase of roughness in both metal and nonmetal, with the decrease of polarization degree of nonmetallic greater than that of metal. Under the same roughness and same temperature, the polarization degree value of infrared radiation of the metallic is always greater than that of the nonmetal. The polarization degree of infrared radiation increases with the incident angle firstly, and then reaches a peak value within a specific incident angle range. The difference of polarization degree value between the metallic and nonmetallic infrared radiation reaches the maximum within a certain incident angle range. This property is useful to distinguish the metal and nonmetal. Finally, long-wave infrared micro-polarization imaging system and near infrared polarization imaging system are used to collect different scene images. Infrared radiation polarization properties of the targets are basically consistent with the theoretical analysis results. This research is of great significance on analyzing the polarization properties of real targets, designing the infrared polarization system and processing the polarization images.
Optimization and analysis of Primary Mirror for laser incoherent combining system
TANG Wei, LIU Li-sheng, Liu Yang, SHAO Jun-feng, GUO Jin
Accepted Manuscript  doi: 10.3788/CO.2019-0161
Abstract(216) FullText HTML(82)
Abstract:
Primary mirror used in high power laser incoherent combining system was designed and analyzed. Firstly, the material and the thickness of primary mirror, the supporting way and lightweight scheme of primary mirror were determined theoretically. Then thermal deformation of primary mirror is calculated by the finite element method, and Topology optimization is executed basing on thermal deformation results. Finally, the impact of Gravity factor, base frequency and ambient temperature on primary mirror P-V value was analyzed. The calculation results show that with temperature ΔT and P-V Value of primary mirror irradiated by Six lasers with the power of 10 kW gradually ascend when laser irradiation time is increasing. When laser irradiation time is up to 3 min, temperature ΔT and P-V Value of primary mirror which is not optimized is 83.4 ℃ and 155 nm respectively, and the thermal deformation values in the irradiated area are inconsistent affecting by the structure, the D-value is ablut 1/6 of primary mirror. Lightweight rate of primary mirror after optimizating is 54.5%, thermal deformation value in laser irradiation area is consistent, and P-V value of primary mirror reduce 1/3. Gravity deformation value of primary mirror at different pitching angles is basically the same, and the maximum P-V value was less than 10 nm. The ambient temperature will cause distortion and defocus aberration, and with the increase of ambient temperature, the aberration would be gradually greater. Modal analysis shows that base frequency of the primary mirror meets the system requirement; The conclusions have a reference value for high power laser incoherent combining system.
Deep Infrared Small Target State Sensing Method for Deep Learning
Huang Le-hong, Cao Li-hua, Li Ning, Li Yi
Accepted Manuscript  doi: 10.3788/CO.2019-0120
Abstract(199) FullText HTML(112)
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  Objective  To propose a new depth learning-based discriminant algorithm for the current spatial infrared weak target state perception method with low accuracy, large artificial interference and high data quality requirements.  Methods  Firstly, the phenomenon of spatial infrared weak target state change is analyzed and a special data set is established. Then the convolutional neural network framework dedicated to target state perception task is established, and innovations are made in local annotation and adaptive threshold. Finally, the simulation data generated by the target radiation intensity information collected by the laboratory is used to train and test the algorithm, and the target state perception evaluation index system is established to evaluate the experimental results.  Results  The experimental results show that the accuracy of the discrimination is 98.27% when the continuous complete radiation intensity information is input. When the radiation intensity information of the segment is input, the accuracy of each state is greater than 90%.  Conclusion  This algorithm makes up for the shortcomings of the current method, which is not sensitive to the low false alarm rate and the incomplete target information. It improves the detection speed and accuracy and better satisfies the demand of spatial infrared weak target sensing tasks.
Method of Enhancing the Quality of In-Line Holographic Images for Micro-Milling Tool
CHENG Ya-ya, YU Hua-dong, YU Zhan-jiang, XU Jin-kai, ZHANG Xiang-hui
Accepted Manuscript  doi: 10.3788/CO.2019-0217
Abstract(213) FullText HTML(100)
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In the method of tool-setting based on digital in-line holography, the zero-order image and the defocused twin-image can form a strong and complex background noise, which is superimposed on the real image and seriously reduces the quality of the reconstructed image. Aiming at the interferential images in digital in-line holography, a holographic image enhancement method based on improved self-snake model is proposed. The improved self snake model select the diffusion intensity according to the gradient of the initial image. The experimental results show that, the improved self-snake model can avoid the appearing of jagged edges and “pseudo-contours” which caused by the large gradient background noise during the diffusion process. This improvement made up for the shortcomings of the self-snake model in the applications of holographic image. In addition, Comparing with the phase retrieval approach and multi-plane reproduction approach, the improved self-snake model filtering method proposed in this paper not only has better suppression for interferential images, but also can enhance the edge of the tool, which is conducive to the realization of tool-setting based on digital in-line holography.
Modeling and numerical simulation of semiconductor switching for ultra-short pulse CO2 laser
GAO Yue-juan, CHEN Fei, PAN Qi-kun, YU Hang-hang, LI Hong-chao, TIAN You-peng
Accepted Manuscript  doi: 10.3788/CO.2019-0159
Abstract(1050) FullText HTML(1003)
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The physical dynamics of ultra-short pulse widths CO2 laser output has been studied in semiconductor switching technology. Firstly, based on the analysis of the generation, recombination and diffusion mechanism of laser-produced carriers, we introduce direct absorption, Auger recombination, plasmon-assisted recombination, ambipolar diffusion process and add Drude theory, to improve the theoretical model of semiconductor switching. Secondly, we simulate and analyze the generation of ultra-short CO2 pulses by two-stage semiconductor optical switches using this model. The results show that the model is in good agreement with the experimental results abroad, which shows the rationality and correctness of the model. Finally, the model is used to analyze the effect of control pulse duration on the efficiency of the two-stage switching. It is found that short control pulse is more conducive to intercepting high-quality ultra-short CO2 pulses accurately and efficiently. Semiconductor switching is an effective technique to realize the output of ultra-short CO2 laser with adjustable pulse width.
Research on modification of Soluble Solids Content sorting line based on light source transmitting and receiving integrated probe
Liu Yande, Rao Yu, Sun Xudong, Xiao Huaichun, Jiang Xiaogang, Xu Hai, Li Xiong, Xu Jia, Wang Guantian
Accepted Manuscript  doi: 10.3788/CO.2019-0165
Abstract(551) FullText HTML(776)
Abstract:
Traditional external quality sorting is now unable to meet the growing demand for quality and taste of the fruit, it has great significance to ensure sugar sorting and the proper taste quality of the fruit by Sugar sorting transformation of traditional external quality sorting line. Near-infrared diffuse reflectance spectroscopy of navel orange has collected under two different detection modes, the spectral energy of diffuse reflection mode of ring is stronger than that diffuse reflection mode of multiple points, and the spectral appearance of these two detection modes are roughly the same. Reduce the effects of stray light and noise by baseline correction, multiple scatter correction, first-order, second-order derivative, etc, of Spectral data preprocessing. Building the partial least squares model of sugar content in two different diffuse reflection detection methods for navel orange and analysis. Experimental results indicate that Optimal use of baseline correction preprocessing methods under two different detection methods; the correlation coefficient of the sugar model is 0.82 at diffuse reflection mode of ring, the root mean square error of predicted is 0.45°Brix; the correlation coefficient of the sugar model is 0.80 at diffuse reflection mode of multiple points, the root mean square error of predicted is 0.48°Brix. The research shows that it is feasible to use PLS modeling combined with near-infrared diffuse reflectance spectroscopy to upgrade the sugar separation line function on the traditional external quality sorting line.
Design of solid-state array laser radar receiving optical system
WEI Yu, JIANG Shi-lei, SUN Guo-bin, ZHANG Xing-xing, WANG Yu-ning
Accepted Manuscript  doi: 10.3788/CO.2019-0166
Abstract(495) FullText HTML(389)
Abstract:
Under the premise of the safety of solid-state array laser radar, in order to improve the image plane energy uniformity of the optical system and increase the energy received by the optical system, to ensure the detection of low SNR in the process and the exploratory of target. Through giving optical parameters to the modeling of the emitted laser energy and the received energy, studying the factors which affect the image illumination of the receiving optical system and pointing out the design method elements of large-field large relative aperture high illumination uniformity optical system.through the ZEMAX optimization analysis, giving the specific implementation of process. Finally, a laser radar receiving lens with λ=905(±5)nm, focal length of 15 mm, relative aperture of 1/1.4, and a field of view of 2ω=76°. Less than 77 mm, MTF value @20 lp/mm is greater than 0.5, relative distortion of 0.85 field of view is less than 8%, image surface illumination non-uniformity is less than 7.2%.which meet the requirements of lidar detection.
Research on ultra-precision grinding and polishing method of the large-scale Al2O3 ceramic guides
LIU Jian, CAI Li-ming, CHENG Xian-kai, GU Guo-gang, YU Yong
Accepted Manuscript  doi: 10.3788/CO.20191203.0663
Abstract(541) FullText HTML(100)
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In order to improve the ultra-precision polishing efficiency of alumina ceramic guide, the relationship between the polishing parameters, such as polishing pressure, polishing speed and abrasive mixing interval and grinding, and polishing efficiency was analyzed. First of all, the polishing discs and abrasive was selected base on alumina ceramic guide's physical parameters and characteristics. Second, with the high precision plane parallel crystal as the detection tool, the number of stripes between crystal and guide quantitatively the polishing efficiency. At the end, the best processing parameters applied to the alumina ceramic guide was obtained: polishing pressure should be controlled around 40 N; the line speed of polishing should be 45 m/min; grinding agent should be added every 30 min. With the same time period, this set of process parameters will obtain higher surfaceaccuracy.
Fan-shaped mid-infrared chiral metamaterials based on indium tin oxide and their circular dichroism
ZHU Ye-xin, LI Ya-nan, SHI Wei-jie, ZHANG Wen-tao, YAN Chang-chun
Accepted Manuscript  doi: 10.3788/CO.2019-0190
Abstract(227) FullText HTML(124)
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A mid-infrared chiral metamaterial was designed to overcome the problems of the large volume and high cost for the traditional mid-infrared laser polarization state control. The fan-shaped chiral structure made of indium tin oxide (ITO) was designed, and its circular dichroism (CD) characteristics in the mid-infrared band were studied. The CD variation characteristics of the structure were discussed by changing the filling material in the fan blade layer, the thickness of fan blades, the size of fan blades, the number of fan blade, and the material of fan blades. The simulation results show that the CD signal varies with these parameters. When the filling material is silicon and the fan blade is six pieces, the strongest CD signal of 0.052 is obtained near the wavelength of 5.3 μm by selecting the appropriate fan thickness and size. The simulation results also show that compared with the silver and gold, the structure made of ITO exhibits broadband circular dichroism, which provides a new idea for the design of broadband polarization-state control devices in the mid-infrared band.
Review Article
Progress of OLEDs prepared by inkjet printing
LIU Xin, YE Yun, TANG Qian, GUO Tai-liang
2020, 13(2): 217-228.   doi: 10.3788/CO.20201302.0217
[Abstract](590) [FullText HTML](350) [PDF 3186KB](81)
Abstract:
In recent years, OLED(Organic Light Emitting Diode) devices have been widely used in small-and medium-sized displays, and have gradually been popularized in large area display applications, such as in TVs and lighting. With the continuous development of organic light-emitting technology, higher requirements drive research on the color and pattern of OLED devices. Compared with the traditional vacuum evaporation process, inkjet printing technology easily colors large-area devices and patterns composite functional materials. It is also simple to implement, low in cost and has a more flexible process. In this paper, the current progress of inkjet-printed OLED devices is reviewed. Furthermore, this paper systematically introduces the development of inkjet printing equipment, by optimizing bank structures to improve the resolution of their display screens, by optimizing the ink formulation and composition ratio to suppress the coffee ring effect of inkjet droplets, and improves the uniformity of display luminescence. Finally, this paper summarizes and provides prospects for the future development of this technology at home and abroad.
Research progress on rock removal by laser technology
GUAN Bing, LI Shi-bin, ZHANG Li-gang, CHEN Shuang-qing
2020, 13(2): 229-248.   doi: 10.3788/CO.20201302.0229
[Abstract](626) [FullText HTML](347) [PDF 4890KB](39)
Abstract:
Laser technology in rock removal is an important research direction in the field of applied optics. It is a complex, high-temperature and high-pressure physical and chemical process with multi-phase, multi-coupling and multi-scale applications. In order to clarify the core difficulties in laser-rock interaction research and to provide an effective theory reference and trend information for researchers, an overview of research on laser rock removal technology is summarized. Firstly, the mechanism of rock removal using lasers is clarified. Then, existing research of laser rock removal is summarized and analyzed from different perspectives, including laser equipment for petroleum drilling and completion, its influencing factors, the phase-change heat transfer of temperature fields, its physical and mechanical properties, and its feasibility in the oil and gas industry. Finally, the advantages of rock removal by laser technology compared with traditional drilling and completion methods are elaborated. In view of the existing problems in laser-rock interaction research, the future development trend of rock removal by laser technology is predicted. The research results show that rock removal by laser technology can lead to research breakthroughs in field-supporting facilities, multi-factor evaluation, multi-field coupling mechanisms and theoretical systems of underground applicability.
Original Article
Broad band and high resolution scanning spectrum calibration technology
CHI Ming-bo, HAN Xin-xin, XU Yang, SHU Feng-feng, WU Yi-hui
2020, 13(2): 249-257.   doi: 10.3788/CO.20201302.0249
[Abstract](288) [FullText HTML](158) [PDF 2094KB](28)
Abstract:
In order to achieve rapid and high spectral resolution detection in the broad band from ultraviolet to near infrared with an atomic emission spectrometer, an ultra-precision rotation stage is used to drive grating rotation to realize spectral segment-scan with high speed and high precision functioning together with an imaging CCD. However, during the scan, the wavelength increment of detector pixel changes nonlinearly with the angle of the grating, and the wavelength increments of different pixels are different, which becomes an obstacle to accurate spectral calibration. To compensate for the nonlinearity of the grating dispersion, the corresponding relationship between the wavelengths of the pixels at both ends of the detector and the rotational angles of the grating is calculated based on the grating equation while the wavelengths of the other pixels are calculated by using the wavelengths of the pixels at both ends with the linear dispersion law. Thus, with this methodology, the calibration of the full band of wavelength is implemented. After calibration, according to the corresponding relationship between the angle and the detection wavelength band, the grating is driven to rotate successively to realize the spectral segment-scan with high resolution and high speed in broad band. The wavelength accuracy and repeatability with this method are tested by using a mercury lamp. The results show that the wavelength accuracy is better than 0.018 nm and the wavelength repeatability is better than 0.001 nm in the wave band from 200 nm to 800 nm.
Research on temperature field in high-power Nd: YAG single crystal fiber laser by analytical method
TIAN Xiao, QI Bing, JIN Fa-cheng, HUANG Bao-yu, ZHANG Jun
2020, 13(2): 258-265.   doi: 10.3788/CO.20201302.0258
[Abstract](315) [FullText HTML](142) [PDF 2634KB](21)
Abstract:
Single Crystal Fiber (SCF) laser is widely applied into scientific research and engineering, owing to its superior thermal management, compact mechanical structure and high power output. In this paper, the temperature field of an Nd:YAG SCF laser related to thermal effect produced by pump laser is presented. By solving the heat conduction equation with the analytical method, the thermal model of Nd:YAG SCF is studied. The temperature distribution of Nd:YAG SCF producing a 946 nm laser by an 808 nm pumping light with power of 86 W is obtained. Results show that the maximum temperature rise at the incident end face of SCF is 30.98℃, obviously lower than that of an Nd:YAG crystal of 94.37℃ under the same conditions. Besides, compared with a temperature rise of 19℃ in SCF obtained by Finite Element Analysis(FEA), temperature rise calculated by analytical method are closer to the experimentally measured value of 31℃. This indicates that the analytical method is more realistic and accurate in describing the temperature field of Nd:YAG SCF. The temperature characteristics of the SCF and the influence of some important parameters are also studied. One of the key factors is the absorption coefficient of the SCF, which has an approximately linear relationship with its temperature rise. Another factor is the core radius of the SCF, which is proportional in value to the rise in temperature. The temperature rise increases with core radius, while decreasing with beam radius of 808 nm pump laser. The root mean square is applied to precisely describe the temperature affected by these parameters. According to the data analysis, uniform distribution in the temperature field can be realized by appropriately selecting the above parameters. The research can be a reference for controlling the thermal effect of single crystal fiber lasers and improving its performance.
Determination of the inner-surface profile of a capsule using chromatic confocal spectroscopy
TANG Xing, WANG Qi, MA Xiao-jun, GAO Dang-zhong, WANG Zong-wei, MENG Jie
2020, 13(2): 266-272.   doi: 10.3788/CO.20201302.0266
[Abstract](256) [FullText HTML](147) [PDF 2433KB](16)
Abstract:
The inner surface profile of capsule, which is one of the essential parameters of laser nuclear fusion capsule, needs to be measured precisely. In this paper, the basic measurement principle of the capsule's inner surface profile, which is based on the white light confocal spectrum and precision air flotation bearing, is analyzed firstly and the corresponding measuring method is presented.Then, the experimental apparatus applied to measure the inner surface profile of capsule is developed, and an auxiliary aligning method based on optical image is proposed. The precise measurement of the inner surface profile of capsule is achieved and the accurate inner surface profile curve of capsule is obtained. Finally, the reliability of measured data is verified experimentally and the measuring uncertainty is analyzed. The experimental results illustrate that the inner surface profile of capsule can be measured accurately using white light confocal spectrum and the measuring uncertainty is less than 0.1 μm.
Optical and mechanical design of polarization filtered dermoscopy
CAO Yi-xing, ZHANG Guo-qi, LU Yong-nan
2020, 13(2): 273-280.   doi: 10.3788/CO.20201302.0273
[Abstract](319) [FullText HTML](292) [PDF 3514KB](18)
Abstract:
Dermoscopy has been widely used in the diagnosis of skin lesions in the clinical field. However, difficulty remains in clear and accurate observation of the size, shape, color depth and size of superficial vascular plexus vessels in the epidermis, dermal-epidermal junction and dermal papilla. Since the epidermis is specularly reflective, it does not change the polarization state of the reflected light. Contrarily, tissue below the epidermal layer of the skin tissue changes the polarization state of the source light. Based on this, we designed a handheld system with a field of view of 22 mm and a magnification of 10×that performs polarized dermoscopy through the use of polarized illumination imaging technology, which more clearly and effectively observe the lesions of deep skin tissue and the morphology of lesions, thereby improving the efficiency of clinical diagnoses.
Testing on diesel engine emission temperature using tunable laser absorption spectroscopy technology
YUAN Zhi-guo, MA Xiu-zhen, LIU Xiao-nan, MU Yan-long, YANG Xiao-tao
2020, 13(2): 281-289.   doi: 10.3788/CO.20201302.0281
[Abstract](286) [FullText HTML](235) [PDF 3327KB](8)
Abstract:
To measure CO2 gas in the exhaust of the D4114B diesel engine, the volume fraction and temperature of the gas were studied and analyzed. Based on the principles of Tunable Diode Laser Absorption Spectroscopy (TDLAS), the process of exhaust gas measurement was simulated using various modules in the SIMULINK library of MATLAB. Through simulation, the relative temperature error of the CO2 was 0.03%. The simulation results were verified with a D4114B marine diesel engine. A visualization window was added to its exhaust pipe and a corresponding test system was installed. A tunable laser with a semiconductor as a working medium was used as the laser light source to carry out on-line tests of the CO2 temperature in the gas emissions. In this study, the relative error of the test was less than 4.0%. It can be seen from the results that the different between the temperature measured by the model built with a SIMULINK and that of the actual diesel exhaust emission is slight. Therefore, the simulation result can be used as a reference for the diesel engine exhaust temperature measurement.
Optimization of matching coded aperture with detector based on compressed sensing spectral imaging technology
LIU Ming-xin, ZHANG Xin, WANG Ling-jie, SHI Guang-wei, WU Hong-bo, FU Qiang
2020, 13(2): 290-301.   doi: 10.3788/CO.20201302.0290
[Abstract](345) [FullText HTML](183) [PDF 4479KB](22)
Abstract:
In practical applications, when the coding template of coded aperture spectral imagers does not match the resolution of their detector, the resolution of the system is lowered. For this problem, by using a mathematical model for the Coded Aperture Snapshot Spectral Imaging system (CASSI), its limiting factors such as a mismatch between its coding template and the detector's resolution are analyzed and the corresponding solutions are given. Considering that the resolution of the coding template is higher than the resolution of the detector, it is proposed that super-resolution technology is introduced to the CASSI system to achieve super-resolution spectral imaging through compressed sensing. For cases in which the resolution of the coding template is lower than the resolution of the detector, a grayscale coding aperture with threshold partitioning grading is proposed to achieve a high-resolution coding mode, which can ensure the resolution of the coded aperture spectral imager. The GPSR algorithm is used to reconstruct the data cube. Experimental results show that the spectral image measured by the CASSI system based on super-resolution theory is more accurate and richer in content. The CASSI system based on a coded aperture with grayscale grading is employed and shown to have higher spatial resolution and spectral resolution. It can be concluded that after optimization, the resolution and imaging quality of the CASSI system are greatly improved and its high resolution components are fully utilized.
Data processing of high-order aspheric surface measurements using CMM in optical fabrication
LI Ang, WANG Yong-gang, WU Zhi-qiang, ZHANG Ji-you
2020, 13(2): 302-312.   doi: 10.3788/CO.20201302.0302
[Abstract](278) [FullText HTML](129) [PDF 3831KB](14)
Abstract:
Surface measurement using a Coordinate Measuring Machine(CMM) is the main method of processing large-aperture high order aspheric mirror fabrication. Because three main types of measurement error exist in original data, the achieved surface residual cannot be directly used in mirror fabrication. Therefore, a series of algorithms for cleaning the errors of CMM point clouds is proposed. Firstly, Probe Radius Compensation(PRC) based on aspherical surface reconstruction is used to compensate for probe radius error in acquired data. Then, the compensation data is processed to remove the rotation and translation errors in the coordinate system. Finally, Surface Residual Denoising(SRD) based on KNN is used to denoise the extracted surface residual data. In the PRC algorithm, a high-precision surface fitting model for probe center points is proposed, which takes rotation and translation errors into consideration. With this model, a correcting vector for each point can be calculated to compensate for the probe radius error. The Simulation experiments show that with PRC algorithm, the precision can reach RMS < 4 nm. By densifying the sampling points with spatial interpolation and optimizing the noise characterization, the proposed SRD algorithm can identify the noise points with a high degree of sensitivity, making the denoising intelligent. Software was constructed according to the error cleaning algorithm and its application shows that it can effectively improve the accuracy and efficiency of CMM point cloud processing during aspheric mirror fabrication.
Enhanced bonding strength between stainless steel and plastic by using laser scanning array structure
LI Yan-qing, FAN Hai-qi, ZHU Kui-ming, LIU Shuang-yu
2020, 13(2): 313-322.   doi: 10.3788/CO.20201302.0313
[Abstract](441) [FullText HTML](133) [PDF 4273KB](7)
Abstract:
In this paper, the surface of stainless steel is treated with a fiber laser to prepare a circular array structure to enhance the bonding strength between stainless steel and plastic. The stainless steel is connected to the plastic under heat and pressure. In order to obtain the expected bonding strength of stainless steel and plastic, the effects of the circular array structure's parameters and bonding parameters on bonding strength are investigated. The results show that when the heating temperature is 400℃, the shear force of stainless steel and plastic bond is the strongest. When the pressure is 75 kN, the shear force of stainless steel and plastic bond is at its strongest. The height, quantity and coverage of burrs on the metal surface after laser treatment have an important effect on the bonding strength between stainless steel and plastics. When the proportion of burr number Tm value is less than 14.82%, the stainless steel and plastic fractured at the bond's surface and the shear force increases with the increase of Tm. When the Tm value is greater than 14.82%, the stainless steel and plastic fractured at the plastic, and the strength of the shear force fluctuates around the average tensile fracture force of 950 N. The coverage of the laser processing area has an impact on the connection strength, 38.5% is the minimum coverage of stainless steel and plastics when they fracture at the plastic, which then has shear force of 900 N.
Propagation properties of elliptical vortex beams in turbulent ocean
LU Teng-fei, ZHANG Kai-ning, WU Zhi-jun, LIU Yong-xin
2020, 13(2): 323-332.   doi: 10.3788/CO.20201302.0323
[Abstract](276) [FullText HTML](130) [PDF 8283KB](11)
Abstract:
The propagation and scintillation index of elliptical vortex beams propagating in oceanic turbulence were simulated using a step-by-step phase screen method.It was found that the beam spot rotates significantly when an elliptical vortex beam transmits through the oceanic turbulence and dark cores are produced, whose number is equal to the topological charge of the beam. A phase singularity with the topological charge m splits into m phase singularities with 1 unit of topological charge and as oceanic turbulence is made stronger, the beam spot experiences greater distortion. It was also found that with an increment in propagation distance, the scintillation index of the elliptical vortex beam is lower than that of the Gaussian beam and the vortex beam in weaker ocean turbulence.Likewise, it was found that the scintillation index reduces more evidently with a larger topological charge when the elliptical vortex beam propagates over a longer distance and that the scintillation index of the vortex beam is lower than that of Gaussian beam after a given transmission distance. In stronger oceanic turbulence, the scintillation indices of the elliptical vortex beams overlap. For oceanic turbulence of different strength, the on-axis scintillation index of the elliptical vortex beam increases with an increment in the rate of dissipation of the mean-square temperature. At a constant propagation distance, a smaller elliptical vortex beam waist width corresponds to a smaller scintillation index.
Analysis of thermal drift in high performance interferometric fiber-optic gyroscopes
LIU Jun-hao, LI Rui-chen
2020, 13(2): 333-343.   doi: 10.3788/CO.20201302.0333
[Abstract](291) [FullText HTML](129) [PDF 3089KB](7)
Abstract:
In order to improve accuracy and thermal performance, an analytical model of thermal-induced drift in interferometric fiber-optic gyroscopes containing all of the known phase perturbations is proposed. Unlike in previous studies, by incorporating fiber birefringence as one of the model's known error sources, the proposed model directly relates gyro performance to mechanical, geometric, thermal and optical parameters in coiled fibers. The influence of these parameters on the gyro drift was numerically calculated according to the presented model. Measurement results of a quadrupole coil within gyroscopes at 10-3 deg/h accuracy confirmed that the bias and its thermal drift induced by the intrinsic high birefringence and its thermal fluctuation in polarization-maintaining fibers are in the order of 10-3 deg/h and 10-2 deg/h. The results also confirmed that the thermal drift induced by the Shupe effect and the photoelastic effect in single-mode fibers are in the order of 10-4 deg/h and 10-3 deg/h, respectively. The proposed model shows that the highly stress-induced birefringence in polarization-maintaining fibers is a dominant source of error that results in bias and thermal drift in high performance interferometric fiber-optic gyroscopes. The model also comprehensively describes how the errors rise from fiber performance in fiber-optic gyroscopes and explains the non-linear dependence that the gyroscopic error has on fiber birefringence.
Performance test of piezoelectric actuators for space inertial sensors
LI Hua-dong, QI Ke-qi, SHI Qiang, WANG Shao-xin, WANG Zhi
2020, 13(2): 344-353.   doi: 10.3788/CO.20201302.0344
[Abstract](289) [FullText HTML](132) [PDF 3748KB](12)
Abstract:
In order to ensure the normal operation of space inertial sensors in orbit, it is necessary to ensure the test mass is fixed during launch to prevent collision with the surrounding capacitor plate. It must grab the test mass after reaching its predetermined orbit and precisely release it in its correct position with minimal residual velocity such that it remains free-floating. In this paper, a piezoelectric linear actuator that is used to grab the test mass is designed, customized and tested for performance. The test results show that the customized piezoelectric actuator can achieve a minimum step size of less than 1 nm, but the step length stability error is large; the maximum driving force at 150 V of input is 72 N; the single stepping drive force is stable; during the process of fixing the test mass, the driving force is stable and the deviation in its stability is 0.16%. These findings meet the needs of the grabbing, positioning, and release mechanisms.
Spectral analysis and theoretical modeling of the working mechanism of meloxicam and lysozyme
CHENG Xu, LIU Bao-sheng, ZHANG Hong-cai
2020, 13(2): 354-362.   doi: 10.3788/CO.20201302.0354
[Abstract](549) [FullText HTML](148) [PDF 2231KB](7)
Abstract:
In order to explore the active mechanisms of meloxicam and lysozyme, the interaction between the molecules of rheumatoid arthritis drugs, meloxicam and lysozyme was studied using fluorescence spectroscopy, synchronous fluorescence spectroscopy and theoretical modeling analysis under the pH=7.40 experimental conditions. The results showed that meloxicam was able to effectively quench the endogenous fluorescence of lysozyme, forming a 1:1 complex and changing the conformation of lysozyme. Thermodynamic results indicated that the main type of meloxicam-lysozyme system was a hydrophobic interaction. The results of theoretical modeling indicated that the system had hydrogen bonds in addition to hydrophobic interactions and that meloxicam was surrounded by the active amino acid residues Glu35 and Asp52 from the lysozyme, which changed the microenvironment of amino acid residues at the active center of the lysozyme. When a patient took meloxicam 15 mg, the protein binding rate of meloxicam to lysozyme W(B) was 3.71%~8.79%, indicating that the combination of meloxicam and lysozyme has little effect on anti-inflammatory and antibacterial function of lysozyme itself, and the system drug binding rate W(Q) was 1.08%~1.14%, indicating that the combination of lysozyme and meloxicam does not affect the efficacy of meloxicam. This study theoretically proved that lysozyme does not have a serious effect on its own function or the efficacy of meloxicam after it is combined with meloxicam in plasma.
Optical design of an ultra-short-focus projection system with low throw ratio based on a freeform surface mirror
YU Bai-hua, TIAN Zhi-hui, SU Dong-qi, SUI Yong-xin, YANG Huai-jiang
2020, 13(2): 363-371.   doi: 10.3788/CO.20201302.0363
[Abstract](325) [FullText HTML](126) [PDF 2658KB](22)
Abstract:
In order to design an ultra-short-focus objective lens with a low throw ratio, a system of ultra-short-focus, low-throw-ratio objective lenses is designed using a freeform surface and refractive-reflective optical structure. The objective lenses consist of a rotationally symmetrical refractive lens group and a freeform surface mirror. A 11.938 mm Digital Micromirror Device (DMD) is used as a spatial light modulator to generate the image source. The normal-weighted iterative optimization method is used to calculate the freeform surface. Finally, the performance of the system is analyzed. The simulation results show that the ultra-short-focus projection objective lens can achieve a 3 048 mm screen projection at a distance of 580 mm. The throw ratio of the system is 0.19, which is extraordinarily low, and the maximum distortion of the system is less than 0.72%. This can meet the design requirements of low throw ratio ultra-short-focus projection objective lenses. This projection system is advantageous for its low throw ratio, low distortion and good imaging quality, which can provide a useful reference for the further development of ultra-short-focus projection systems.
Far-field range fluorescence enhancement by a hybrid metal-dielectric structure
DONG Lin-xiu, CHEN Zhi-hui, YANG Yi-biao, FEI Hong-ming, LIU Xin
2020, 13(2): 372-380.   doi: 10.3788/CO.20201302.0372
[Abstract](298) [FullText HTML](226) [PDF 3220KB](27)
Abstract:
In order to improve the sensitivity of fluorescence biosensing and solve the near-field limitations to enhancement when the fluorescent nanoparticle is in the structure's far-field range, a large-scale hybrid metal-dielectric structure(Ag-Si structure) is proposed to enhance fluorescence in the far-field range.This hybrid metal-dielectric structure is different from previous metal-dielectric structures because it achieves fluorescence enhancement when the fluorescent nanoparticle is in the structure's far-field range due to scattering and interference. In this paper, the Ag-Si structure is investigated with respect to its excitation process and the emission process using the Finite-Difference Time-Domain (FDTD) method. In the excitation process, the intensity of the Ag-Si structure's fluorescence is higher than that of the bare glass structure and the electric field distribution of the Ag-Si structure is more uniform in the slit between the two pillars than it is in the metal structure (Ag structure). With this structure, fluorescence enhancement can be achieved and its detection of molecular motion behavior is more accurate. In the emission process, fluorescence enhancement in the Ag-Si structure is higher than that of the bare glass structure when the fluorescent nanoparticle is in the structure's far-field range. The mechanisms that achieve fluorescence enhancement in the Ag-Si structure are scattering and interference. Fluorescence is scattered upward by the silver film while the silver and silicon pillars on both sides of the structure simultaneously scatter the partial fluorescence, then the fluorescence interferes and propagates to the far-field to achieve fluorescence enhancement.Further advocating its use, an Ag-Si structure is simple to fabricate and integrate, allowing seamless application in biosensing.
Study on grating of Smith-Purcell free-electron laser
MENG Xian-zhu
2020, 13(2): 381-395.   doi: 10.3788/CO.20201302.0381
[Abstract](375) [FullText HTML](364) [PDF 3550KB](17)
Abstract:
In order to study the relationship between the output frequency of Smith-Purcell free-electron laser and the depth, length and width of grating groove, the rectangular grating size of Smith-Purcell free-electron laser is discussed by means of theoretical analysis and particle simulation methods. First, by particle simulation, we found that the output frequency of Smith-Purcell free-electron laser decreases with the increase of grating groove depth, grating groove length and grating groove width. Then, the grating groove of Smith-Purcell free-electron laser is discussed by means of theoretical analysis. It is found that each grating groove can be equivalent to an LC resonant circuit. There are two kinds of radiation in Smith-Purcell free-electron laser, one is Smith-Purcell radiation and the other is LC oscillatory radiation. Finally, the LC oscillatory radiation of grating groove is estimated as well. It is found that the simulated values of output frequency of Smith-Purcell free-electron laser and the estimation values of LC oscillatory radiation of grating groove are both on the order of 102 GHz, and the variation is consistent. It is inferred that the output frequency of Smith-Purcell free-electron laser should be determined by grating groove rather than resonator.
Activation effect of complex medium on the optical propagation properties of optical quantum well
SU An, MENG Cheng-ju, JIANG Si-ting, GAO Ying-jun
2020, 13(2): 396-410.   doi: 10.3788/CO.20201302.0396
[Abstract](415) [FullText HTML](348) [PDF 2745KB](9)
Abstract:
By using the transmission matrix, the activation effect of complex medium on the optical propagation properties of optical quantum well has been studied. The result shows that, the light transmissivity and internal local electric field of an optical quantum well can be activated by complex medium. There is always an internal local electric field in the optical quantum well made of whether real medium or complex medium. The local electric field will always cause the frequency quantization and the appearance of discrete narrow transmission peaks in the transmission spectrum. Active impurities are added to the medium A. When the imaginary part of dielectric constant of complex medium, namely k, is positive, both the local electric field in the optical quantum well and the transmissivity of discrete narrow transmission peaks will be attenuated. With the increase of k value, the monotonic attenuation of internal local electric field becomes more obvious. However, the sensitivity of the response of local electric field to the positive imaginary part k is different at different wavelengths of optical quantum well, and the electric field at the central wavelength of the quantum well is the most sensitive to the k value. When the imaginary part of dielectric constant of complex medium, is negative, both the local electric field in the optical quantum well and the transmissivity of discrete narrow transmission peaks will have an amplified gain. As the value of negative imaginary part |k| increases, the internal local electric field will increase to a maximal value and then become attenuated. However, the maximal value of the local electric field in gain amplification and the corresponding |k| value are different at different wavelengths of the quantum well. To be specific, the local electric field in the short-wave direction of the quantum well is the most sensitive to |k| value, while the local electric field in the long-wave direction is the least sensitive to |k| value. The modulation mechanism of complex medium towards the light transmission characteristics of optical quantum well has positive guiding significance for the theoretical research and practical design of new optical filters, optical amplifiers and optical holophotes, and for the research of internal mechanism of light transmission characteristics of an optical quantum well.
Optimization design and experimental study of micro-Fourier transform spectrometer
ZHAO Yun, LV Jin-guang, QIN Yu-xin, TAO Jin, LIANG Zhong-zhu, WANG Wei-biao, NI Qi-liang, MENG De-jia, LIANG Jing-qiu
2020, 13(2): 411-425.   doi: 10.3788/CO.20201302.0411
[Abstract](264) [FullText HTML](149) [PDF 5741KB](24)
Abstract:
In order to achieve the goal of miniaturization and light weight of Fourier transform spectrometer, a light-weight grid beam splitter structure was designed instead of the traditional parallel plate beam splitter. The influence of the grid edge of the grid beam splitter on spectrum reconstruction was analyzed, and the tolerance of production error was proposed. The micro-Fourier transform spectrometer was modeled and simulated, and the optimal structure of the grid beam splitter was obtained. The spectral inversion was performed by system simulation, and the restored spectrum was obtained. The spectral error introduced by the grid beam splitter was calculated. The construction and debugging of the prototype was completed, and the recovered spectrum of the actual system was obtained, which proved the feasibility of the miniaturized system. Compared with the traditional Fourier transform spectrometer, the miniaturization system has the advantages of small volume and good stability, and can be used for online monitoring.
Progress of OLEDs prepared by inkjet printing
LIU Xin, YE Yun, TANG Qian, GUO Tai-liang
2020, 13(2): 217-228.   doi: 10.3788/CO.20201302.0217
Abstract(590) FullText HTML(350) PDF 3186KB(81)
Abstract:
In recent years, OLED(Organic Light Emitting Diode) devices have been widely used in small-and medium-sized displays, and have gradually been popularized in large area display applications, such as in TVs and lighting. With the continuous development of organic light-emitting technology, higher requirements drive research on the color and pattern of OLED devices. Compared with the traditional vacuum evaporation process, inkjet printing technology easily colors large-area devices and patterns composite functional materials. It is also simple to implement, low in cost and has a more flexible process. In this paper, the current progress of inkjet-printed OLED devices is reviewed. Furthermore, this paper systematically introduces the development of inkjet printing equipment, by optimizing bank structures to improve the resolution of their display screens, by optimizing the ink formulation and composition ratio to suppress the coffee ring effect of inkjet droplets, and improves the uniformity of display luminescence. Finally, this paper summarizes and provides prospects for the future development of this technology at home and abroad.
Research progress on rock removal by laser technology
GUAN Bing, LI Shi-bin, ZHANG Li-gang, CHEN Shuang-qing
2020, 13(2): 229-248.   doi: 10.3788/CO.20201302.0229
Abstract(626) FullText HTML(347) PDF 4890KB(39)
Abstract:
Laser technology in rock removal is an important research direction in the field of applied optics. It is a complex, high-temperature and high-pressure physical and chemical process with multi-phase, multi-coupling and multi-scale applications. In order to clarify the core difficulties in laser-rock interaction research and to provide an effective theory reference and trend information for researchers, an overview of research on laser rock removal technology is summarized. Firstly, the mechanism of rock removal using lasers is clarified. Then, existing research of laser rock removal is summarized and analyzed from different perspectives, including laser equipment for petroleum drilling and completion, its influencing factors, the phase-change heat transfer of temperature fields, its physical and mechanical properties, and its feasibility in the oil and gas industry. Finally, the advantages of rock removal by laser technology compared with traditional drilling and completion methods are elaborated. In view of the existing problems in laser-rock interaction research, the future development trend of rock removal by laser technology is predicted. The research results show that rock removal by laser technology can lead to research breakthroughs in field-supporting facilities, multi-factor evaluation, multi-field coupling mechanisms and theoretical systems of underground applicability.
Application of planar antenna in field-effect transistor terahertz detectors
WANG Xiao-Dong, YAN Wei, LI Zhao-feng, ZHANG Bo-wen, HUANG Zhen, YANG Fu-hua
2020, 13(1): 1-13.   doi: 10.3788/CO.20201301.0001
Abstract(398) FullText HTML(174) PDF 2480KB(15)
Abstract:
In order to improve the responsivity and reduce the noise equivalent power of Field-Effect Transistor (FET) THz detectors, a suitable planar antenna structure is necessary.In this paper, we investigate the research progress of FET THz detectors integrated with planar antenna structures. Firstly, we analyze the working principle of FET THz detectors and clarify that an integrated planar antenna could effectively improve the detector's performance by enhancing its coupling efficiency with terahertz waves. Secondly, we present some typical planar antennas and discuss their pros and cons. These include the dipole antenna, the patch antenna, the slot antenna, the grating-gate, and others, which are each compared with respect to responsivity for the detectors. Finally, we find that the responsivity of the FET THz detectors can be greatly improved when applying planar antenna structure and that each type of antennas contributes uniquely. This work introduces several planar antennas integrated into FET THz detectors, including the performance and research progress of various antennas.Some existing problems are described and some predictions of the future development trends for this technology are summarized.
Progress of quantum dot backlight technology
YE Yun, YU Jin-hui, LIN Shu-yan, CHEN En-guo, XU Sheng, GUO Tai-liang
2020, 13(1): 14-27.   doi: 10.3788/CO.20201301.0014
Abstract(552) FullText HTML(213) PDF 4222KB(24)
Abstract:
Quantum dots (QDs) have received widespread attention because of their adjustable emitted wavelength of light, color purity and high quantum efficiency, which have great potential in applications requiring high-color-quality displays with photoluminescence. In this paper, the progress of QD backlights based on each QDs on-chip, QDs on-surface and QDs on-edge are reviewed, including their principle, structures and current applications. Then, several other novel QD backlight structures are also introduced, prompting a proposal for two novel QD backlight technologies. One is the QDs scattering diffusion plate, which is prepared by injecting molding with a mixture of QDs and polymer at a low temperature. The other is a QD microstructure light guide plate, which is fabricated by transferring QDs on the surface of a light guide plate through screen printing or inkjet printing. Both of these two QD plates can achieve high color gamut while being simple to process, being low in cost and holding high production efficiency. These have wide applications in high color gamut liquid crystal displays.
Research progress on laser-produced plasma light source for 13.5 nm extreme ultraviolet lithography
ZONG Nan, HU Wei-min, WANG Zhi-min, WANG Xiao-jun, ZHANG Shen-jin, BO Yong, PENG Qin-Jun, XU Zu-yan
2020, 13(1): 28-42.   doi: 10.3788/CO.20201301.0028
Abstract(461) FullText HTML(223) PDF 2768KB(17)
Abstract:
The semiconductor industry is the backbone of the high-tech and information age. Lithography technology, one of the core technology of the semiconductor industry, has become a key research subject all around the world. This article mainly discusses the light source of 13.5 nm Extreme Ultraviolet Lithography (EUVL) by using Laser-Produced Plasma (LPP). It makes a brief introduction to the principles behind this technology and the development history of this field at home and abroad. The introductions include the materials used in the multilayer mirror, and rationale for the selection of materials, the shape and design of the target and the type of laser. At the same time, this article points out that the main problems for the EUVL are light debris reduction and the conversion efficiency improvement of EUV light.This paper also gives special analysis of the light source output devices of 13.5 nm EUVL machines produced by international famous companies——Gigaphoton of Japan and ASML of the Netherlands, which can generate more than 100 W level EUV power. Finally, this article summarizes and forecasts future research related to this technology.
Recent progress in tunable metalenses
LIN Yu, JIANG Chun-ping
2020, 13(1): 43-61.   doi: 10.3788/CO.20201301.0043
Abstract(365) FullText HTML(169) PDF 8833KB(23)
Abstract:
Emerging optical devices demand miniaturized, integrated and intelligent optical zoom systems, thus stimulating development in nano-optoelectronics. Metalenses are two-dimensional planar structures with lens function composed of arrays arranged specifically to equally focus wavelengths of light. Due to their ultrathin and lightweight properties and their ease of integration, it is expected that they will revolutionize optics by replacing the conventional bulky, curved lenses used that pervade optical devices. However, once the micro/nano-structures of a metalens are fabricated, their shape and size cannot be modified, which can not realize the real-time adjustment of focusing and will limit the further development of metalenses' functions and applications. Currently, substantial effort is being devoted to solving this problem. One of the most attractive aspects of metalenses is in the way they combine metasurface lenses with smart materials. In this article, we first provide an overview of novel tunable metalenses. Then, we elaborate and analyze their regulatory principles and device performance, respectively. Finally, we summarize the current problems and difficulties facing the development of tunable metalenses and describe the direction of their future development.
Research progress of quantum dot enhanced silicon-based photodetectors
ZHU Xiao-xiu, GE Yong, LI Jian-jun, ZHAO Yue-jin, ZOU Bing-suo, ZHONG Hai-zheng
2020, 13(1): 62-74.   doi: 10.3788/CO.20201301.0062
Abstract(440) FullText HTML(184) PDF 6598KB(14)
Abstract:
Silicon-based photodetectors have been widely investigated due to their high reliability, easy integration and low cost. With the development of artificial intelligence and autonomous vehicles, research and performance enhancement of silicon-based photodetectors is an important field of research. Quantum dots are excellent light-conversion and light-modulation materials due to their superior absorption coefficient, tunable spectra, high photoluminescence quantum yield and simple integration. The tunable light absorption and phototuminesence properties of quantum dots make them suitable materials for enhancing the detection. Quantum dots enhanced silicon-based photodetectors are emerging as a new technique to advance the performance of detection and imaging. In particular, they show potential to expand the functionality of CCD and CMOS devices and further satisfy increasing demands for detection. In this review, we summarized the progress of quantum dot-enhanced silicon-based photodetectors in the field of ultraviolet detection, infrared imaging, polarization detection and spectral detection, hoping to attract the attentions of domestic colleagues.
Development of additively manufacturing metal mirrors
TAN Song-nian, DING Ya-lin, XU Yong-sen, LIU Wei-yi
2020, 13(1): 75-86.   doi: 10.3788/CO.20201301.0075
Abstract(352) FullText HTML(162) PDF 4337KB(17)
Abstract:
With the rapid development of optical measurement and remote sensing, the demand for weight, volume and environmental adaptability in folding optical systems are continuously increasing. Metal mirrors based on additive manufacturing technology are gradually gaining the attention and research of scholars at home and abroad for their easy to realize optimum design, rapid manufacturing process and high processing performance. Compared to conventional metal mirrors, additively manufacturing metal mirrors strengthen the stiffness of the mirror and achieve a higher degree of weight reduction simultaneously. Furthermore, additively manufacturing mirrors can meet the environmental adaptability and rapidity requirements of optical systems. This paper first discusses the evaluation indicators of metal mirrors. Second, the development status and technical parameters of metal mirrors based on additive manufacturing technology are reviewed. The design and preparation of metal mirrors for additive metal fabrication and the post-treatment of substrates are discussed. Then, through analysis, the preparation process and key technologies of additively manufacturing metal mirrors are summarized. Finally, prospects for additively manufacturing mirror applications are presented.
Advances in organic nonlinear crystals and ultra-wideband terahertz radiation sources
XU De-gang, ZHU Xian-li, HE Yi-xin, WANG Yu-ye, YAO Jian-quan
2019, 12(3): 535-558.   doi: 10.3788/CO.20191203.0535
Abstract(634) FullText HTML(206) PDF 10967KB(152)
Abstract:
Nonlinear optical(NLO) crystals are the determinant in nonlinear optics. Recently, a variety of new organic crystals have been developed to further improve the output energy and conversion efficiency and to broaden the bandwidth of THz waves based on nonlinear optical frequency conversion technology. These crystals have become an ideal material for generating THz waves with their excellent performance in nonlinear optics. In this paper, the properties of different organic crystals are introduced in the classification of ionic crystals and nonionic molecular crystals, and the progress of THz sources that use the different organic crystals are summarized. At the same time, the applications and the trends in the development of broadband THz radiation using organic crystals are analyzed.
Image processing method for ophthalmic optical coherence tomography
CAI Huai-yu, ZHANG Wei-qian, CHEN Xiao-dong, LIU Shan-shan, HAN Xiao-yan
2019, 12(4): 731-740.   doi: 10.3788/CO.20191204.0731
Abstract(1326) FullText HTML(146) PDF 2700KB(36)
Abstract:
Optical coherence tomography(OCT) has become a hot research topic in the field of clinical medicine due to its features including micron-level high resolution, non-invasive imaging and instantaneity, which has developed rapidly and made much progress and break throughs in recent years. In this paper we briefly review the applications of OCT in ophthalmology, discuss the methods of speckle noise reduction in the spatial and frequency domains of OCT images, and summarize the precise positioning and stratification method of each layer of tissue in the OCT anterior segment and retina image. The advantages and disadvantages of the segmentation methods based on gray value search, active contour model, graph and pattern recognition algorithms are analyzed and compared. In addition, the existing problems with segmentation methods are discussed and the corresponding solutions and feasible optimization schemes are proposed. Analysis and evaluation of clinical diagnostic indicators of ophthalmic diseases are discussed. According to the needs in ophthalmology and the current status of OCT image processing, the development trends and level of OCT image processing are discussed and analyzed.
The regularized phase tracking technique used in single closed interferogram phase retrieval
WANG Xian-min, LIU Dong, ZANG Zhong-ming, WU Lan, YAN Tian-liang, ZHOU Yu-hao, ZHANG Yu-peng
2019, 12(4): 719-730.   doi: 10.3788/CO.20191204.0719
Abstract(402) FullText HTML(123) PDF 4295KB(81)
Abstract:
Different kinds of modulation methods are usually adopted when physical quantities, such as temperature, forces and deformation, are measured in interference. Fringe patterns carry measurement information of those quantities and are usually later analyzed for its retrieval. Single closed fringes are generally what is recorded by CCD. When the experimental conditions are not conducive to phase shifting, loading wave and other modulation means, the regularized phase tracking(RPT) technique can retrieve a continuous phase map directly from a single interferogram, making it the most effective method. In recent years, RPT technique has been improved to achieve higher processing power, algorithm robustness and retrieval accuracy for complex fringe patterns, ultimately making it more practical. In this paper, we introduce the basic algorithm principle and how the RPT technique is applied in the retrieval of single interferograms, review the technique's relevant modifications and developments in recent years, cite some examples used for phase retrieval and speculate the direction of its future development.
Realization of a watt-level 319-nm single-frequency CW ultraviolet laser and its application in single-photon Rydberg excitation of cesium atoms
WANG Jun-min, BAI Jian-dong, WANG Jie-ying, LIU Shuo, YANG Bao-dong, HE Jun
2019, 12(4): 701-718.   doi: 10.3788/CO.20191204.0701
Abstract(763) FullText HTML(195) PDF 8142KB(75)
Abstract:
In order to meet the demand for single-photon Rydberg excitation of cesium atoms in the field of atomic physics, we investigated the key technolgies of single-frequency continuous wave(CW) tunable ultraviolet(UV) laser at 318.6 nm. Combining the fiber lasers, fiber amplifiers and the nonlinear crystals, we achieved 318.6 nm UV laser over 2 Watt output with cavity-enhanced second-harmonic generation following the sum-frequency generation of two infrared lasers at 1 560.5 nm and 1 076.9 nm in PPLN crystal. The typical root-mean-square fluctuation of UV laser power was less than 0.87% within 30 minutes. The electronic side-band locking scheme based on a temperature controlled hyper-fine ultra-stable ultra-low-expansion cavity placed in an ultra-high vacuum chamber was used to achieve the continuously tuning of UV laser in a wide range while still keeping it locked. The continuously tunable range was larger than 4 GHz and the residual frequency fluctuation of UV laser was about 16 kHz. We employed this high-power single-frequency continuously tunable UV laser system for the direct 6S1/2nP3/2(n=70-100) Rydberg excitation of cesium atoms with atomic vapor cells in experiments. After that, relevant theoretical analysis and research have been done. With a magneto-optical trapped cesium atomic ensemble, single-photon Rydberg excitation using the UV laser system was achieved with a pure optical detection scheme.

Supervisor: Chinese Academy of Sciences

Sponsors: the Changchun Institute of Optics, Fine Mechanics, and Physics (CIOMP), CAS and Chinese Optical Society (COS)

Editor-in-Chief: Wang Jiaqi, Academician

ISSN 2095-1531

CN 22-1400/O4

CODEN ZGHUC8

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