Polarization is a crucial factor in shaping and stabilizing mode-locking pulses. This study develops an orthogonally polarized numerical modeling of passive mode-locked graphene fiber lasers for generating orthogonally polarized dissipative solitons (DSs). The focus is on analyzing the influence of orthogonal polarization in this net-normal dispersion birefringent cavity caused by the polarization-dependent graphene microfiber saturable absorber. The research results demonstrate that the recovery time of such saturable absorbers significantly affects the characteristics of the orthogonally polarized DSs’ output pulses, including energy, pulse width, time-bandwidth product, and chirps. Results show that its recovery time of 120 fs is optimal, producing two orthogonally polarized narrow dissipative soliton pulses with large chirps of about 7.47 and 8.06 ps. This has significant implications for the development of compact, high-power, polarized dissipative soliton fiber laser systems.

In this paper, a phase noise suppression algorithm based on real-imaginary-alternate pilots was proposed for a coherent optical orthogonal frequency division multiplexing communication system with offset quadrature amplitude modulation (CO-OFDM-OQAM). The algorithm uses the properties of laser phase noise and the symmetry law of the intrinsic imaginary interference (IMI) to design real-imaginary-alternate pilots. In combination with a linear fitting, it is able to accurately estimate the common phase error (CPE) for CO-OFDM-OQAM. As the compensation was performed in the frequency domain, the computational complexity was significantly reduced compared to the time-domain phase noise suppression algorithms. We built a numerical simulation platform for a polarization multiplexed CO-OFDM-OQAM system with an effective bit rate of 65 GBits/s. Through it, the suppression effect of the proposed method on phase noise was examined. The transmission performance of the system with different laser linewidths and number of subcarriers was investigated. The results obtained confirm that the linewidths required to reach the FEC limit for BER are equal to 801.1, 349, and 138.4 KHz for a fixed OSNR of 25 dB and a total number of subcarriers of 256, 512, and 1024, respectively. For the system using a 16-QAM modulation format with a number of subcarriers of 256 or 512, it compensates well for the laser phase noise without affect the power peak-to-average ratio.

An optical fiber magnetic field sensor is proposed and experimentally demonstrated by using a U-shaped cavity based on in-fiber Mach-Zehnder interferometer (MZI) coated with magnetic fluid (MF). The magnetic field sensor is manufactured by splicing a section of single-mode fiber (SMF) between two sections of SMF with designed fiber geometric relationships. As the geometric symmetry MZI is strongly sensitive to the surrounding refractive index (RI) with a high sensitivity up to −13588 nm/RIU and MF’s RI is sensitive to magnetic field, the magnetic field sensing function of the proposed structure is realized. The results show that the magnetic field sensitivity reaches as high as 137 pm/Oe, and the magnetic field range is almost linear from 0 to 250 Oe. Our magnetic field measurement structure has the advantages of small size, low cost, easy manufacturing, robustness, high sensitivity, good repeatability and easy integration with fiber systems.

To provide a reliable theoretical basis for the selection, mounting, and error compensation of the polarization device in the synchronous phase-shift transverse shear interference system, based on the Jones matrix principle, we construct an error model reflecting the degree of influence of the errors of quarter-waveplate and polarizer array on the measurement results in the system. Then, we quantitatively analyze how the measurement results are influenced by the following factors: the phase delay error of quarter-waveplate, fast-axis azimuthal angle error, and transmission-axis azimuthal angle error of the polarizer array. The simulation results show that the wavefront measurement errors are 0.00002λ(PV) and 0.000062λ(RMS) when the phase delay error of the quarter-waveplate is within ±1°, 0.0001λ(PV) and 0.00006λ(RMS) when the adjustment accuracy of the quarter-waveplate is within ±2°, and 0.003λ(PV) and 0.001λ(RMS) when the azimuthal angle error of the polarizer array is within ±1°. The measurement errors are. According to the simulation results, the polarization components in the measurement system were selected. At the same time, two polarization components with different levels of accuracy were chosen for comparison experiments. The experimental results indicate the following conclusions: the deviations of the residual values of the experimental results from the residual values of the simulation results in terms of the PV and the RMS values are less than λ/20, and the validity of the model can be verified to a certain extent. The mathematical model proposed in this paper can provide a reliable theoretical basis for the selection of polarization devices in synchronous phase-shifted transverse shear interference systems.

The recent advent of miniature head-mounted fluorescence microscopes has revolutionized brain science research, enabling real-time imaging of neural activity in the brains of free-moving animals. However, the pursuit of miniaturization and reduced weight often results in a limited field of view, constraining the number of neurons observable. While larger field-of-view systems exist, their increased weight can impede the natural behaviors of the subjects. Addressing these limitations, a novel design utilizing a metalens schematic is proposed. This approach offers the benefits of being ultra-light, ultra-thin, and capable of high-quality imaging. By deriving the aberration formula specific to hyperbolic phase metalens and using it as a foundation, a design for a miniature fluorescence microscope was developed. This microscope boasts a 4 mm×4 mm field of view and a numerical aperture (NA) of 0.14, effectively correcting seven primary aberrations. The resulting prototype, weighing a mere 4.11 g, achieves a resolution of 7.8 μm across the entire field of view. This performance is sufficient to image neural activity in the brains of freely moving mice with single-cell resolution.

Aiming to the problem of the complicated preparation of existing optical fiber fluorescence temperature sensing probes. We propose a simple, cost-effective, and high-performance optical fiber fluorescence temperature sensor based on a capillary liquid core. Firstly, a mixed solution consisting of temperature-sensitive rhodamine B and temperature-insensitive rhodamine 123 was used as the temperature-sensitive material and encapsulated in a stainless-steel capillary to prepare a sensing probe. The ratio of the fluorescence emission peak intensities of the two dyes was utilized for temperature sensing. Subsequently, the sensing probe’s mixed solution concentration and capillary structural parameters were optimized. Then, the performance of the sensor was tested. Finally, the sensor was applied to real-life temperature measurements. The experimental results demonstrate that the sensor has a temperature response range of 30−70 °C and that there is a quadratic correlation between the fluorescence intensity ratio and the temperature, with the fitted correlation coefficient as high as 0.9984. The sensor exhibits excellent accuracy, repeatability, and stability, with more than three months of service time. Moreover, it can be well-utilized to detect temperature in daily life. The optical fiber fluorescence temperature sensor shows significant potential for real-time monitoring and remote detection applications

Trace gases, as important constituents of the atmosphere, play an important role in the ecology of the planet. In order to realize the requirements of, wide-band, hyperspectral and all-weather continuous measurement, a hyperspectral imaging spectrometer operating in occultation detection mode is designed in this paper. The system is a dual-channel structure with a common slit, the UV-visible channel adopts a single concave grating, and the infrared channel adopts a structure combining Littrow and immersion grating, which effectively reduces the volume. The software was used to optimize the optical structure, and the optimization results showed that the spectrometer operated in the range of 250−952 nm wavelengths, of which the UV-visible channel operated in the wavelength range of 250−675 nm, the spectral resolution was better than 1 nm, the MTFs were all higher than 0.58 at a Nyquist frequency of 20 lp/mm, and the RMS values at various wavelengths of the full-field-of-view were all less than 21 μm; the infrared channel operates in the wavelength band of 756−952 nm, the spectral resolution is better than 0.2 nm, the MTF is higher than 0.76 at the Nyquist frequency of 20 lp/mm, and the RMS value at each wavelength in the whole field of view is less than 6 μm, all of them meet the design requirements. It can be seen that the hyperspectral imaging spectrometer system can realize the occultation detection of trace gases.

Broadband absorption performance in resistive metamaterial absorbers (MA) has always been disturbed by its ohmic sheet element. This paper proposes a comprehensive scheme based on integrating resistive MA and plasmonic structure (PS) to enhance the stable absorption performance. Theoretical investigation indicated that the PS can inspire multi-resonance based on dispersion engineering, and that the localized electric field takes effect on the surface of the ohmic sheet accordingly. Simulation and experimental measurement demonstrated that the proposed resistive plasmonic absorbing structures (PAS) can achieve stable and highly efficient absorption within the frequency band from 7.8 to 40.0 GHz with the ohmic sheet ranging from 100 to 250 Ω/sq. In conclusion, the proposed integration of PS and resistive MA provides an efficient pathway to optimize performance for various applications.

This paper outlines the design and usage of equipment developed to measure the photoelectrical parameters of CCD and electron-multiplying charge-coupled device (EMCCD) chips. The test system’s automatic and manual modes provide measurements of dark currents, the output amplifier’s responsivity, charge transfer efficiency, charge capacity, and other parameters. The system can be configured for measurements of different formats and architectures (CCD/EMCCD) both on wafer and in package. The developed equipment was used for 576 × 288, 640 × 512, 768 × 576, 1024 × 1024, 1280 × 1024 CCD and EMCCD chip testing and sorting.

In order to solve the requirement of polarized light navigation for accurate position information of feature points in the sky, an accurate detection method for the sun position of imaging system based on all sky polarization mode is proposed. Compared with the traditional method of detecting the solar position based on spot, this method uses the inherent polarization information in the atmosphere to complete the accurate measurement of the solar position, which has the characteristics of simple detection method, high accuracy and wide application range. The optical acquisition system consists of three micro large field of view camera modules and polarizers, which makes the structure more compact, smaller and lower in height. Starting from the principle, the algorithm of solving the sun position is simulated first, and then the algorithm is verified in three weather environments (sunny, occluded, and aerosol) using the optical acquisition system. When the weather is clear, the sun is detected at different times of the same day, and the accuracy of the measured sun's altitude and azimuth are 0.024° and 0.03° respectively; when the sun is blocked by high-rise buildings, the accuracy of the measured sun's altitude and azimuth are 0.08° and 0.05°; when the sun is blocked by the branches and leaves of trees, the accuracy of the measured sun's altitude and azimuth are 0.3° and 0.1° respectively. Only when the aerosol concentration exceeds a certain amount will the Rayleigh distribution mode of polarized light be destroyed, which will affect the detection accuracy of Position of the Sun. The experimental results show that this new detection method can not only meet the needs of polarized light navigation for the position of the sun, but also provide a new way of exploration for fans who like to explore the mysteries of the universe.

To further enhance the control performance of the precision tracking system for laser communication, this paper studies the control method of the fast steering mirror (FSM) driven by voice coil motor. Aiming at the problems of strong cross coupling characteristics and external disturbances in the FSM, a composite fast nonsingular terminal sliding mode control strategy integrating feedforward decoupling compensation and fixed-time extended state observer is proposed. Firstly, the coupling transfer function matrix model of the FSM with double inputs and double outputs is established by using system identification method, and the feedforward decoupling compensator is designed to compensate for the coupling components and achieve motion decoupling between the X-axis and Y-axis. Secondly, the fixed-time extended state observer is designed for each decoupled single-axis model, to achieve fixed-time estimation of angular velocity and external disturbances simultaneously. Then, the fast nonsingular terminal sliding mode surface is constructed, and the exponential power function is adopted to replace the sign function in control law design, so as to improve the convergence speed of the system and suppress the chattering of sliding mode, the stability of the proposed control system and the finite-time convergence of tracking error are proved based on Lyapunov stability analysis method. Finally, the effectiveness of the proposed composite control strategy is verified by comparative experiments. The experimental results show that under the 100 Hz strong disturbances, the FSM tracking 60 Hz and 120 Hz circular trajectories, the average absolute values of its trajectory tracking error are 0.0036° and 0.0131° respectively, indicating that the system can maintain good tracking performance. The proposed composite control strategy is validated to be effective in meeting the high-precision and strong anti-disturbance requirements of the FSM for laser communication.

In this paper, a metamaterial terahertz band-stop filter is designed based on a symmetrical H-type structure. The continuous metal arm of this H-type structure can flow current, which can provide an effective reference for expanding the application of metamaterial filters in the field of electronics. Using electromagnetic simulation software CST Microwave Studio 2021, the filtering characteristics of the filter were studied, and The geometric parameters of the filter are determined by changing the arm length, period length and double H distance. The results show that the structure can realize the function of polarization selection. Under the condition of y polarization, the filter has no obvious resonance peak in the range of 0.2−2.3 THz, but the transmittance ranges from −15 dB to −3 dB. Under the X-polarization condition, a stopband of 0.15 THz FWHM bandwidth can be obtained at the center frequency of 1.34 THz, and the transmission parameter is about −30 dB. In order to verify the simulation results, the sample of metamaterial filter was prepared by micromachining technology, and the sample was tested by transmissed-terahertz time-domain spectroscopy system. The test results were in good agreement with the simulation results.

Non-destructive, non-contact phase-shifting digital holography has distinct advantages in identifying micro-optical components. Because traditional phase-shifting digital holography requires fine control and cumbersome calibration of the phase shifter, its optical path is susceptible to mechanical vibration interference, which reduces the quality of the holographically reproduced image. This paper proposes a vortex phase-shifting digital holography for the micro-optical element surface measurement method with the help of the special phase distribution of vortex light. The method utilizes a helical phase plate to modulate the vortex phase and introduce a high-precision phase shift. Based on the constructed vortex phase-shifting digital holographic microscopy experimental setup, the actual phase shifts between phase-shift interferograms were determined using the interferometric polarity method, the relationship between the rotation angle of the helical phase plate and the phase shift was calibrated, and the feasibility of the vortex phase shift was experimentally verified. Repeated measurement experiments were carried out on the micro-lens arrays, and the measurement results were compared with those of the ZYGO white light interferometer. The results indicate that a single micro-lens's average longitudinal sagittal height is 12.897 μm with an average relative error of 0.155%. The proposed method enables highly precise measurement of the surface topography of micro-optical elements. It offers the advantages of easy operation, high stability, and high accuracy.

Laser communication utilizes light waves as the transmission medium. It offers many advantages, including high data rates, expansive bandwidth, compactness, robust interference resistance, and superior confidentiality. It has the critical capability to enable high-speed transmission and secure operation of space information networks. Prominent research institutions have committed to studying a series of challenges that need to be solved in the process of networking laser communication technology, including point-to-multipoint simultaneous laser communication, all-optical switching and forwarding of multi-channel signals within nodes, node dynamic random access, and network topology design. Numerous demonstration and verification experiments have been conducted, with a subset of these research results finding practical applications. Based on the analysis and discussion of space laser communication networking technology, this paper summarizes the development of laser communication networking technology both domestically and internationally, focusing on the application of laser communication networking technology in the fields of satellite constellations, satellite relays, and aviation networks; furthermore, it presents a review of pertinent domestic research methodologies, experimental validations, and technical solutions; finally, it predicts the development trend of laser communication networking technology and applications.

The TFT-LCD industry is moving towards the direction of high efficiency and low costs. During the manufacturing process, it has been found that various photoresists require different vacuum drying time. To reduce manufacturing time and increase panel yields, it is necessary to clarify the factors that can influence and reduce the vacuum time. This paper explored the relationship between pumping time and the properties of photoresist materials. It was found that the thermal stability of the photoresist had a negligible relationship with the pumping time. The compactness and hydrophobicity of the photoresist are highly correlated with the vacuum drying time. High compactness and high hydrophobicity can effectively avoid water vapor intrusion and storage in the photoresist during fabrication and consequently reduce pumping times. Overall, this work could guide the future development of new photoresists for the TFT-LCD industry.

In order to improve the accuracy and success rate of geographical guidance, according to the structural characteristics of the roll-pitch electro-optical pod, a mathematical model of geographical guidance was developed through three steps: first, establishing the coordinate system; second, solving the target coordinates; and third, calculating the frame angle. Speed forward feed and small domain search modes were introduced on this basis. The frame angle calculation error affected by inertial navigation measurement error and target distance was simulated, and the results show that the longitude, latitude, and heading angle errors had a greater influence on the pitch angle calculation error; nonetheless, the errors of elevation and horizontal attitude angle had a greater influence on the calculation error of the roll angle. Improving the positioning accuracy of inertial navigation can further reduce the frame angle calculation error and improve the geographical guidance accuracy; however, when the heading angle decreases below 0.1 degrees and the horizontal attitude angle decreases below 0.05 degrees, then the influence weight of the attitude angle error also decreases. The improvement in guidance accuracy is no longer evident when attitude angle errors are reduced. Increasing target distance sharply decreases the error of frame angle calculation. Finally, the guidance test with pitch and roll mean square errors of less than 0.12 degrees shows the algorithm's accuracy and the simulation analysis's effectiveness.

To address the issues of blurred edge details and poor contrast in multi-scale transform fused images obtained using remote sensing detection methods for mixed background features, an image fusion approach that combines the sparse representation of non-downsampled contour wavelet transform and a guided filter was utilised to enhance the quality and visual appearance of the fused images. This method involved several steps: Firstly, a multi-scale and multi-directional decomposition was performed on both spectral and polarimetric images using non-downsampled contour wavelet transform to isolate the feature information in each subband; secondly, the low-frequency subbands were fused using a sparse representation approach to minimize the loss of contrast in the fused image; additionally, the high-frequency subbands were fused through a bootstrap filter to enhance the detail information and the contours of the image; finally, the low-frequency and high-frequency fusion coefficients were inverted using non-downsampled contour wavelet inversion to generate the final fused image. Analysis indicates that this method has increased the contrast of the fused image by up to 54.5% relative to the original spectral image and by 15.4% compared to the polarimetric image. This has resulted in a fused image in which it is easier to distinguish objects in shadows within a mixed background. This method was used to fuse spectral and polarimetric images captured by a polarimetric spectral imager at different wavelengths, which resulted in true-colour reproduction. These true-colour restored images demonstrate that this fusion method retains environmental information within the mixed background while distinguishing the object from the background, effectively improving the image quality of polarization spectral remote sensing detection imaging. This approach enhances the integrity and authenticity of image information in polarization spectral remote sensing detection imaging, thereby expanding its application scope in remote sensing detection of complex environments and image recognition.

With the rapid advancement of spectral imaging technology, the use of multispectral filter array (MSFA) to collect the spatial and spectral information of multispectral images has become a research hotspot. The uses of the original data are limited because of its low sampling rate and strong spectral inter-correlation for reconstruction. Therefore, this paper proposes a multi-branch attention residual network model for spatial-spectral association based on an 8-band 4 × 4 MSFA with all-pass bands. First, the multi-branch model was used to learn the image features after interpolation in each band; second, the feature information of the eight bands and the all-pass band were united by the spatial channel attention model designed in this paper, and the application of multi-layer convolution and the convolutional attention module and the use of residual compensation effectively compensated the color difference of each band and enriched the edge texture-related feature information; finally, the preliminary interpolated full-pass band and the rest of the band feature information were used in feature learning by residual dense blocks without batch normalization on the spatial and spectral correlation of multispectral images to match the spectral information of each band. Experimental results show that the peak signal-to-noise ratio, structural similarity, and spectral angular similarity of the test image under the D65 light source outperform the state-of-the-art deep learning method by 3.46%, 0.27%, and 6%, respectively; in conclusion, this method not only reduces artifacts but also obtains more texture details.

Passively Q-switched mode-locked operation was realized for the first time by inserting a semiconductor saturable absorption mirror (SESAM) mode-locking element into a Tm:CaYALO₄(Tm:CYA) laser using in-band pumping technology. The laser cavity adopted an X-type four-mirror cavity structure, and the pump source was an Er:Y₃Al₅O₁₂(Er:YAG) solid-state laser with a central wavelength of 1650 nm. Output coupling mirrors with transmittances of 0.5%, 1.5%, 3%, and 5% were used to study the laser’s continuous wave (CW) output and mode-locking output characteristics. The experimental results show that the laser has the best output characteristics when an output coupling mirror with a transmittance of 5% is used. The maximum power of 894 mW and the maximum slope efficiency of 16% were obtained when the laser operated in the CW regime. After the CW power was optimized to the highest, the SESAM mode-locked element was added to the optical path. When the absorbed pump power became greater than 1.86 W, the laser operation entered an unstable Q-switched state; when the absorbed pump power increased to 5.7 W, a stable passively Q-switched mode-locked operation was achieved; when the absorbed pump power reached 6.99 W, a mode-locked pulse laser with a maximum output power of 399 mW was obtained by using a 5% output mirror. At that time, the repetition frequency under the Q-switched envelope was 98.11 MHz, the pulse width was 619.4 ps, and the corresponding maximum single pulse energy was 4.07 nJ. The mode-locked pulse modulation depth in a Q-switched envelope was observed to be close to 100%. The experimental results show that same-band pumping technology can be used in lasers to generate Q-switched mode-locked pulses, which provides a new pumping method for generating ultrashort pulse lasers.

As aircraft maneuverability increases, multi-frame infrared small target detection methods are becoming insufficient to meet detection requirements. In recent years, significant progress has been achieved in single-frame infrared small-target detection methods based on deep learning; however, infrared small targets often lack shape features and have blurred boundaries and backgrounds, obstructing accurate segmentation. Based on this, an indistinguishable points attention-aware network for infrared small object detection was proposed. First, potential target areas were acquired through a point-based region proposal module while filtering out redundant backgrounds; then, to achieve high-quality segmentation, the fine mask boundary module determined disordered, non-local indistinguishable points in the coarse mask, fused multi-scale features, and modeled the attention pixel by pixel; finally, the point detection head generated a fine segmentation mask by re-predicting the indistinguishable points’ attention-aware features. The proposed method reached 87.4 mAP and 63.4 mAP on the publicly available datasets NUDT-SIRST and IRDST, and the F-measure reached 0.8935 and 0.7056, respectively. It can achieve accurate segmentation in multi-detection scenarios and multi-target morphology, suppressing false alarm information while controlling the computational overhead.

In order to improve the shafting motion accuracy of two-dimensional turntables such as photoelectric theodolites, this paper establishes a mathematical model based on Jacobian-Torsor theory, which can account for both the structural error of parts and the coupling amplification effect. Aiming at a shafting structure with one fixed end and one swimming, an analysis method of partial parallel structure was proposed. Through numerical simulation analysis, the impact of each part’s structural errors on the motion accuracy of the shafting and the optimal shafting assembly scheme were obtained. The results of assembly and adjustment of a photoelectric theodolite with an optical diameter of 650 mm show that assembly optimization improved the motion accuracy of the shaft system by 32.1%. The precision model and optimization method of shafting motion provide a theoretical basis for the shafting adjustment and tolerance design of two-dimensional turntables such as photoelectric theodolites.

In order to study the influence of the output performance of the gas flow tract structure on the output performance of the flowing-gas diode pumped alkali laser(FDPAL), this article is combined with the FDPAL theoretical model combined with the FDPAL mid -gas heat transfer, fluid mechanics and laser dynamics process to use side pump Rb vapor FDPAL(Rb-FDPAL) is a simulation object, analyzing the impact of the output performance of the Rb-FDPAL output performance of the gas flow direction, the cross-sectional area and the shape of the runner. The results show that when the horizontal flow method is adopted, when the cross-sectional area of the flow tract and the connection part of the gas flow tract to the steam pool to the masonry structure, the vortex in the vapor is effectively suppressed, the gas flow rate increases, the thermal effect of the steam pool is smaller, Rb-FDPAL's laser output power and slope efficiency are higher, the simulation results are consistent with the experiment.

The data simulation for space situational awareness (SSA) can provide critical data support for the development, testing, and validation of space surveillance equipment and situational awareness algorithms (including detection, tracking, recognition, and characterization of space object), playing a significant role in building SSA capabilities. Taking the optical data simulation for space-based situational awareness as the research subject, the purpose and main research content of SSA data simulation are presented, and the typical research methods and processes of SSA optical modeling and simulation are set forth. The current research status and progress in domestic and foreign related research are introduced, covering the imaging modeling and simulation achievements of different optical sensing systems such as binocular vision sensors, LiDAR, infrared sensors, visible light telescopes, and star trackers. The development trend of SSA data simulation research is analyzed, providing reference for future research ideas and approaches of SSA data simulation.

This study proposes an active polarization imaging approach that utilizes laser illumination to tackle the issue of low target detection contrast in strong light backgrounds, which is a challenge in conventional photoelectric detection. The study examines the coupling relationship between the polarization characteristics of three typical target materials and the scattering angle of a laser beam. This is achieved by constructing a laser incident bidirectional reflection distribution model, a laser incident polarization bidirectional reflection distribution model, and a target surface polarization model of laser illumination. Backlight observation experiments are conducted in a controlled darkroom to verify the impact of the scattering angle of the laser beam on the polarization characteristics of the target. The experimental results show an 86.11% increase in target contrast for active polarization imaging under strong light background compared to traditional passive intensity imaging. Additionally, different target materials exhibit differing visible polarization characteristics under varying beam dispersion angles, with metallic materials is higher than that of non-metallic materials. This result aligns with theoretical analysis and support the advantages of active polarization imaging. The outdoor solar backlight observation experiment verifies the applicability of the research method in high-intensity light and long-distance settings. This study can lay a theoretical foundation for improving accurate target perception under a strong light background.

To address the issues of inaccurate measurements and unstable calibration processes in conventional Shack-Hartmann wavefront sensors (SHWFS), we propose a high-precision absolute calibration method using spherical waves generated by the sensor. The SHWFS experiences an extremely precise calibration process with 128×128 sub-apertures. This is achieved using a method of spherical wave obtained through theoretical derivation in conjunction with the constructed experimental device for spherical wave calibration. The structural parameters of the SHWFS (f, w, and L₀) are calculated precisely. Also, the measurement accuracy of the SHWFS is verified following calibration. The experimental results demonstrate that by using this method to calibrate the Shack-Hartmann wavefront sensor, its wavefront recovery accuracy reaches a PV of 1.376×10⁻²λ and an RMS of 4×10⁻³λ (where λ=625 nm), respectively. Additionally, its repeatability accuracy reaches a PV of 3.2×10⁻³λ and an RMS of 9.76×10⁻⁴λ (where λ=625 nm), respectively. These findings suggest that this method is suitable for enhancing the measurement accuracy of high-precision calibration of SHWFS with large aperture.

In response to the demand for high imaging quality and high chromaticity in color digital cameras, this paper investigates the optical system design and camera spectral optimization methods of 3CMOS cameras based on Philips prisms. By modeling the optical path of the Philips prism, the structural parameters of the prism were optimized, reducing the volume of the system while ensuring total internal reflection and exit window size. Based on this method, the Philips prism 3CMOS camera optical system was designed, with a field of view angle of 45 ° and a relative aperture of 1/2.8. The system's MTF was greater than 0.4 in the full field of view and full band at Nyquist sampling frequency of 110 lp/mm. Subsequently, based on the fundamental principles of chromaticity, a vector imaging model for Philips prism cameras was established. The problem of thin film spectral shift caused by changes in light incidence angle was analyzed, and a correction model for spectral shift under wide beam conditions was proposed. Four sets of optical thin films in the camera were designed and optimized using this model. Through optical path simulation experiments and color error analysis, based on the optimized camera spectrum, the average color error of the system was reduced by 15.8%, and the color non-uniformity of the image plane was reduced by 60%. The results indicate that the optical system designed in this article has good imaging quality, and the optimized camera spectrum achieves good color performance and uniformity.

The Terahertz wave possesses characteristics of high penetration, low energy, and fingerprint spectrum, etc., making it widely used in the detection field. Therefore, developing a Terahertz wave detection optical imaging system holds substantial significance and wide application prospects. Firstly, we refer to the structure of Tessar objective lens, which consists four lenses. The balance equations of aberration for the system were established through the application of the aberration theory of the paraxial optical system. Subsequently, we provide a solution function and method of the initial structure parameters of the system. Then, we combine it with optical design software to further correct the aberration of the system. Finally, we design a Terahertz wave detection optical imaging system with a large aperture. The optical system consists of four coaxial refractive lenses with a total focal length of 70 mm, an F-number of 1.4, and a full field of view angle of 8°. The value of modulation transfer function (MTF) in the range of full field of view angle is greater than 0.32 at the Nyquist frequency of 10 lp/mm, and the root mean square (RMS) radius of the diffused spot in each field of view is less than the airy disk radius. Finally, the paper analyzes and discusses the various tolerance types of the system. The results indicate that the Terahertz wave detection optical imaging system, designed in this paper, has a large aperture, a simple, compact form, a lightweight structure, excellent imaging performance and simple processing, which meets the design requirements, and it has important applications in the field of high-resolution detection and other fields within the Terahertz wave band.

Ghost images, as a type of stray light, are caused by residual reflected light between the optical surfaces. These images can degrade image clarity, annihilation targets, and severely affect the performance of optical systems. To investigate the impact of ghost images on optical system performance, we developed a Modulation Transfer Function (MTF) calculation model under the influence of ghost images generated by secondary reflection. This paper first introduces the method of analyzing and describing using the paraxial approximation. Then, starting from the definition of the MTF, and considering the influence of ghost image irradiance on the modulation of the image plane, a calculation model for calculating the MTF under the influence of ghost images is constructed. After performing calculations and comparing them to simulation results, it was found that the maximum mean square error was less than 0.049373, which verifies the accuracy of the model. Furthermore, a detailed analysis was conducted, examining cases that exhibited larger errors and clarifying the range in which this calculation method can be applied The research results indicate that the paraxial approximation method is both accurate and reliable when calculating the MTF under the influence of ghost images is accurate, and is applicable in most cases. This study serves as a valuable exploration in the ghost image analysis of optical systems.

To improve both the efficiency and accuracy of point cloud registration, this study proposed an improved method based on point-by-point advance feature point extraction. Firstly, the point-by-point advance method extracts point cloud feature points rapidly, and greatly reduces the number of point clouds, while retaining the characteristics of the point cloud model. The KN-4PCS algorithm, using normal vector constraints, conducts a preliminary registration of the source and target point cloud. Finally, the fine registration is achieved with the two-way Kd-tree optimized LM-ICP algorithm. In the open point cloud data registration experiment of Stanford University, the average error is reduced by about 70.2% compared with the SAC-IA+ICP algorithm, and the registration time is reduced by about 86.2% and 81.9%, respectively. The algorithm maintains high accuracy and low time consumption even with varying degrees of Gaussian noise. In the point cloud registration experiment of indoor objects, the average registration error was measured to be 0.0742 mm with an average algorithm time of 0.572 s. The comparison and analysis of Stanford open data and real indoor scene object point cloud data shows that this method can effectively improve the efficiency, accuracy, and robustness of point cloud registration. Furthermore, this study establishes a strong foundation for indoor target recognition and pose estimation through the point cloud.

3D reconstruction is crucial for digitizing artifacts, and the accuracy of 3D point cloud registration is a significant metric for evaluating the reconstruction quality. In practice, artifact point cloud data includes numerous details, and using conventional downsampling methods may result in the loss of such details, thereby affecting registration accuracy. This paper proposes a method for downsampling and registering artifacts point clouds based on curvature features. First, 3D point clouds data of artifacts are obtained using linear matrix laser measurement. Next, the curvature values of all points are calculated, and a curvature threshold is set for point cloud classification. We downsample different point sets based on their feature attributes, with varying weights assigned to retain the shape features and details of the point cloud as much as possible. Finally, point cloud registration is achieved through the use of a rigid transformation model. Compared to the traditional global downsampling ICP method, the downsampling processing before point cloud registration reduces the point cloud data to 1/3 of the original size. The average distance decreases from approximately 0.89 mm to 0.59 mm, while the standard deviation decreases from about 0.29 mm to 0.18 mm. This approach guarantees the accuracy of downsampling and registration and is applicable to various artifacts point cloud data.

To address the problem of limited field of view measurement in traditional monocular vision measurement systems, this paper proposes an omnidirectional spatial monocular vision measurement method based on a two-degree-of-freedom rotary table. First, calibrate the rotating axis parameters of the double-degree-of-freedom rotary table. Then, take pictures of the checkerboard calibration plate fixed with the two-degree-of-freedom rotary table using an auxiliary camera. Extract the position coordinates of the checkerboard corner points and convert them to the same camera coordinate system. The direction vector of the initial position axis parameter was obtained through PCA (principal component analysis) plane fitting, and the position parameter in the rotation axis parameter in the initial position was determined using the method of spatial least squares circle fitting. The camera data acquired at various angles is transformed into coordinate system one using the rotary table rotation angle and the Rodrigues formula. This enables measurement of the target in the horizontal and vertical omnidirectional space. Finally, verification of the measurement accuracy of the proposed method was conducted using a high-precision laser rangefinder. Additionally, experiments comparing the omnidirectional spatial measurement ability of the method with the binocular vision measurement system and wMPS measurement system were conducted. The results indicate that the method achieves a measurement accuracy comparable to that of a binocular vision system. However, it also surpasses the binocular vision system in term of measurement range, making it applicable for omnidirectional spatial measurements.

In order to improve the visible light band (0.3 μm~0.9 μm) A simplified method for high-temperature calibration in the visible light band has been proposed to improve the efficiency of high-temperature calibration. First of all, a high-temperature calibration model of visible light band with exposure time variable is proposed. Through a large number of experimental data, it is found that the gray value of each channel of RGB camera not only changes linearly with the increase of exposure time, but also changes linearly with the increase of Black-body radiation brightness. Then, the specific form of high-temperature calibration model of visible light band is determined. Then, in order to solve the unknowns in the simplified high-temperature calibration model of visible light band, image data under two exposure times are collected under two Black-body radiation brightness, and then the image data is processed to obtain the high-temperature calibration curve of RGB camera under any exposure time. Finally, a comparison is made between the simplified visible light band high-temperature calibration method proposed in this article and the conventional visible light band high-temperature calibration method based on exposure time. The experimental results show that the maximum relative error between the calculated value of the R channel and the calibrated value is 3.38%, the maximum relative error between the calculated value of the G channel and the calibrated value is 2.56%, and the maximum relative error between the calculated value of the B channel and the calibrated value is −1.14%. Moreover, the relative error between the calculated value of each channel and the calibrated value does not exceed 3.50%. The mathematical model proposed in this article can effectively simplify the traditional high-temperature calibration method, thereby greatly shortening the high-temperature calibration time and improving the calibration efficiency of high-temperature calibration.

Bright-field imaging can provide cellular and histological morphological information, while fluorescence imaging can provide expression information of key proteins. Dual-modal correlation imaging based on both techniques is currently a common method for examining tissue samples in medical and scientific research. In clinical examination, however, correlation imaging between adjacent tissue slices is often used for observation. In such cases, both the tissue structure and the cellular level may be altered more or less, which is unfavorable when the sample volume is insufficient, the number of cells on the slices is limited, or precise point-to-point morphological information is required. Therefore, the development of single-slice dual-modal optical correlation imaging techniques which provides both tissue morphology and the distribution and expression of multiple target proteins on a single slice, can help to more accurately describe tumors and their microenvironment. This technique is particularly important in renal pathological testing where sample size is small. Renal pathology requires the use of bright-field imaging to obtain pathomorphological information of tissues and cells after hematoxylin-eosin staining, while the use of fluorescence imaging to obtain the distribution and expression of multiple target proteins is a mandatory molecular test for renal pathology screening. This paper focuses on the tissue sample processing methods that allow the coexistence of hematoxylin-eosin staining and immunofluorescence staining on the same renal slice. Improvements and comparative evaluations of the staining, de-colorizing and re-staining processes, as well as innovative fusion techniques for single-slice dual-modal imaging.

In order to meet the requirements of the national synchrotron radiation source, the anisotropic wet-etching technology of small blazed angle monocrystalline silicon grating is studied, and the blazed grating suitable for the medium wave soft X-ray band is prepared. Based on the rigorously coupled wave theory, the structural parameters and process tolerance of the small blazed angle grating are designed. In the crystal alignment process, the crystal orientation of the silicon wafer is determined by ring-preetching, and then the grating mask is aligned with the crystal direction of monocrystalline silicon <111> based on the frequency doubling adjustment method. At the same time, the effect of the photoresist ashing technique and the active agent on the groove quality of the grating is investigated, and the scintillating gratings close to the ideal sawtooth groove shape are successfully prepared by the monocrystalline silicon anisotropic wet etching process. The experimental results show that the blazed angle of the prepared grating is 1°, the linear density is 1200 gr/mm, and the root mean square roughness of the blazed surface is less than 0.5nm. This method can be applied to the fabrication of the medium wave soft X-ray band blazed grating, which can greatly reduce the difficulty and cost of fabrication while achieving high diffraction efficiency.

A novel photonic quasi-crystal fiber (PQF) sensor based on surface plasmon resonance (SPR) is designed for simultaneous detection of methane and hydrogen. In the sensor, Pd-WO₃ and cryptophane E doped polysiloxane films deposited on silver films are the hydrogen and methane sensing materials, respectively. The PQF-SPR sensor is analyzed numerically by the full-vector finite element method and excellent sensing performance is demonstrated. The maximum and average hydrogen sensitivities are 0.8 nm/% and 0.65 nm/% in the concentration range of 0% to 3.5% and the maximum and average methane sensitivities are 10 nm/% and 8.81 nm/% in the range between 0% and 3.5%. The sensor provides the capability of detecting multiple gases and has large potential in device miniaturization and remote monitoring.