The complex reflective properties of highly reflective surface bring overexposure and underexposure problems to surface structured light technology. In order to reconstruct the measured surface completely and accurately, a multiple exposure method is proposed, which can predict the exposure time according to the reflective intensity of the measured surface. Firstly, the camera response curve of the imaging system is obtained by projecting a series of uniform gray images at different exposure times, and at the same time, the irradiance image which can reflect the reflection intensity of the measured surface is calculated. Then, the fuzzy C-means clustering method is used to adaptively segment different irradiance regions of the target and obtain the central irradiance of each region, and the optimal exposure time is predicted for different reflection regions based on the camera response curve. Finally, the 3D reconstruction of the highly reflective surface is realized by combining the multiple exposure fusion algorithm. The experimental results show that the proposed method can simultaneously reconstruct the strongly reflective area and the excessively dark area of the aluminum alloy surface, with the reconstruction error less than 0.5mm, the maximum deviation reduced by 74.78% and the standard deviation reduced by 48.96%. The proposed method can correctly predict the exposure time according to the regional reflection characteristics, effectively overcome the problems of phase loss and phase distortion caused by regional overexposure and regional darkness, and completely and accurately reconstruct different reflection regions of the highly reflective surface.

In order to accurately measure an object’s three-dimensional surface shape, the influence of sampling on it was studied. First, on the basis of deriving spectra expressions through the Fourier transform, the generation of CCD pixels was analyzed, and its expression was given. Then, based on the discrete expression of deformation fringes obtained after sampling, its Fourier spectrum expression was derived, resulting in an infinitely repeated "spectra island" in the frequency domain. Finally, on the basis of using a low-pass filter to remove high-order harmonic components and retaining only one fundamental frequency component, the inverse Fourier transform was used to reconstruct the signal strength. A method of reducing the sampling interval, i.e., reducing the number of sampling points per fringe, was proposed to increase the ratio \begin{document}$ m $\end{document} between the sampling frequency and the fundamental frequency of the grating. This was done to reconstruct the object’s surface shape under the condition of \begin{document}$m > 4$\end{document} more accurately. The basic principle was verified through simulation and experiment. In the simulation, the sampling intervals were 8 pixels, 4 pixels, 2 pixels, and 1 pixel, the maximum absolute error values obtained in the last three situations were 88.80%, 38.38%, and 31.50% in the first situation, respectively, and the corresponding average absolute error values are 71.84%, 43.27%, and 32.26%. It is demonstrated that the smaller the sampling interval, the better the recovery effect. Taking the same four sampling intervals in the experiment as in the simulation can also lead to the same conclusions. The simulated and experimental results show that reducing the sampling interval can improve the accuracy of object surface shape measurement and achieve better reconstruction results.

Non-uniformity correction is a crucial procedure for infrared imaging systems to achieve high quality infrared images. Currently, many large-aperture infrared radiation measurement system encounter numerous issues, such as non-uniformity correction being time-consuming and inadequate in-field applications. In this paper, a rapid and extensive dynamic non-uniformity correction algorithm is suggested for the requirement of continuous change of integration time in infrared radiation measurement system. The algorithm considers the impact of integration time effect and stray radiation of the optical system. The experimental verification was conducted by employing cooled mid-wave infrared radiation characteristic measurement system with a 25 mm aperture. The correction efficiency of the classical algorithm and the proposed algorithm are compared. The results indicate that the proposed algorithm is 3.4 times more efficient than the traditional non-uniformity correction algorithm. This paper evaluates the effect of the raw image and the two algorithms on the image correction using residual non-uniformity. Multiple integration times (0.6 ms, 3 ms and 3.5 ms) are used to simulate the continuous change of integration. The results indicate that the residual non-uniformity of the proposed algorithm is consistent and the corrected image has been effectively corrected.

To address the bottleneck that makes the conventional polarization spectral imaging method difficult to apply to the ballistic platform, a fast multi-dimensional imaging guidance optical system based on array optics is proposed. The correlation model between channel resolution and telescopic magnification is constructed. The precise matching and efficient utilization of the parameters of the microlens array, spectral filter array, and micro-nano-polarization array detector are realized. Based on the conventional guidance head and commercial polarization detector, a multi-dimensional imaging guidance optical system with spherical dome is designed. The system adopts a 4×4 optical field segmentation layout, forming 16 spectral channels through the visible light band with a spectral resolution of 16 nm. A polarization spectral data cube in four polarization directions, such as 0°, 45°, 90°, and 135° is acquired efficiently under the conditions of a single optical path and a single detector. The system has an effective focal length of 150 mm and a structure length of 145 mm. Simulation results show that the full-field modulation transfer function of the system is close to the diffraction limit at the Nyquist frequency for 16 channels. The imaging quality meets the requirements of bullet-loaded target multi-dimensional detection and identification.

Quantum Fisher information is used to witness the quantum phase transition in a non-Hermitian trapped ion system with balanced gain and loss, from the viewpoint of quantum parameter estimation. We formulate a general non-unitary dynamic of any two-level non-Hermitian system in the form of state vector. The sudden change in the dynamics of quantum Fisher information occurs at an exceptional point characterizing quantum criticality. The dynamical behaviors of quantum Fisher information are classified into two different ways which depends on whether the system is located in symmetry unbroken or broken phase regimes. In the phase regime where parity and time reversal symmetry are unbroken, the oscillatory evolution of quantum Fisher information is presented, achieving better quantum measurement precision. In the broken phase regime, quantum Fisher information undergoes the monotonically decreasing behavior. The maximum value of quantum estimation precision is obtained at the exceptional point. It is found that the two distinct kinds of behaviors can be verified by quantum entropy and coherence. Utilizing quantum Fisher information to witness phase transition in the non-Hermitian system is emphasized. The results may have potential applications to non-Hermitian quantum information technology.

In order to improve the image quality and variable range of focal length of liquid lens, by using dielectrophoretic and hydraulic driven, the double-interface liquid lens based on combination structure is designed, which mainly consists of dielectrophoretic double-liquid lens and PDMS membrane liquid lens. Firstly, the liquid lens model is established with Comsol software, the surface profile changes of droplets and PDMS membrane under different voltages are studied, then the surface profile data of two surfaces are derived. Secondly, the aspherical expression is used to fit with Matlab software, the interface profiles of droplets and PDMS membrane under different voltages and the corresponding aspherical coefficient are obtained. Finally, the corresponding double-interface combined liquid lens optical model is built with Zemax software, the image plane is selected as Gaussian image plane, then through the fabrication and the preliminary experimental research of the corresponding device, the simulation and experimental data are compared and analyzed. The results show that the variable range of focal length of the designed double-interface liquid lens based on the combined structure of the simulation is consistent with that of the experiment. Additionally, the zoom ratio can reach 2.1254 and the imaging resolution can reach 101.5937 lp/mm in the experiment. The double-interface liquid lens designed based on the combination structure has the advantages of simple compact structure, strong interface adjustability and high resolution imaging.

With its advantages of high torque ratio and stable low-speed operation, the Segmented Arc Permanent Magnet Synchronous Motor provides high-performance drive technology support for large-diameter astronomical telescope observations. Due to the existence of other internal and external interferences such as parameter distortion, harmonics, etc. during the operation of the motor, it is a challenge to improve the performance of the motor. To this end, this paper proposes an integral sliding mode controller based on a new reaching law and a hybrid control strategy that combines an expanded state observer and a load observer, aiming to optimize the traditional sliding mode control and enhance the anti-interference ability of the system. The parameters of the traditional reaching law are complicated and cannot suppress chattering well. The new reaching law simplifies the parameters and effectively overcomes the system chattering. Secondly, an expanded state observer is used to estimate the feedback speed, and then the q-axis current information and the estimated precise speed data are combined as the input of the load torque observer, which further improves the load observation performance and converts the load observation value into current for pre-processing. Feedback compensation is used to improve the anti-interference performance of the motor. Simulation and experimental results show that the proposed dual observer method can accurately observe the motor's speed and load, significantly enhancing the motor's ability to resist load disturbances; at the same time, the new sliding mode speed controller used reduces the motor speed overshoot, and suppresses the buffeting of the sliding mode to a certain extent, providing theoretical and experimental support for arc motors in high-precision observation applications of large-aperture astronomical telescopes.

In order to precisely control the direction of laser beams, this paper analyzes the error caused by the grating tilt in the system based on the optical beam pointing algorithm of the dual liquid crystal polarization grating system. Firstly, a ray tracing method based on the diffraction grating equation is used to solve the outgoing beam pointing, introducing the incident beam pointing and grating tilt angle. The correctness and accuracy of this method are verified by comparing with simulation results. Secondly, by analyzing different situations of grating tilt, this article provides expressions for the grating attitude under different tilt conditions, and, in combination with the ray tracing method, obtains the expressions for the outgoing beam pointing for corresponding situations, analyzing the zeroing error and rotation error caused by grating tilt. The research results indicate that within the range of 0° to 0.3° grating tilt angle, the zeroing errors are within 0.25 mrad and 2 mrad respectively, and the rotation errors are around 85 mrad and 430 mrad respectively. This article describes a method for accurately calculating the pointing direction and grating tilt errors in the exit beam of a dual liquid crystal polarization grating system.

Beam arrays have great application value in free-space optical communication. The light intensity evolution and the on-axis scintillation index of radial Gaussian vortex beam array propagating through atmospheric turbulence are analyzed based on multi-phase screen simulation. The effect of initial beam parameters on the scintillation properties of radial Gaussian vortex beam array is studied, and the variation of the on-axis scintillation index values of radial Gaussian vortex beam array and a Gaussian vortex beam is compared. The results indicate that in the weak fluctuation regime, the on-axis scintillation index of Gaussian vortex beams remains within a numerical range of less than 1, while the on-axis scintillation index of radial Gaussian vortex beam arrays is around 1. In the medium fluctuation regime, the on-axis scintillation index of the radial Gaussian vortex beam array is smaller than that of a single Gaussian vortex beam. And the on-axis scintillation index of radial Gaussian vortex beam array decreases with the decrease of orbital angular momentum and the increase of radial array radius. The research results have certain theoretical significance and application value for vortex optical communication in turbulent atmospheric environments.

Liquid crystal optical phased array (LC OPA) is widely used in lidar, laser communication and laser weapons to scan and control laser beams. In order to realize the optimal design of LC OPA and high-precision control of laser beam, this paper focuses on the influence of working wavelength, number of pixels, pixel size and effective grey levels on beam pointing accuracy. Firstly, according to the principle of liquid crystal phase modulation, the effective scanning angle and diffraction efficiency of the period grating and the variable period grating methods are simulated and analyzed. Secondly, assuming the phase modulation is equally divided by the driving voltage, the variation law of the pointing error with the working wavelength, the number of pixels, the pixel size and the effective grey levels is simulated and analyzed, and the multivariable universal formula is derived. Thirdly, the pointing accuracy of the nonuniform phase modulation is simulated, analyzed, and compared with the results of the uniform phase modulation. Finally, the relationship between the effective grey levels and the pointing error is verified by experiments, and the validity of the empirical formula is preliminarily confirmed. The research results can provide a theoretical basis for the design of LC OPA.

In order to acquire and monitor the low frequency vibration signal, a two-dimensional vibration sensor with symmetrical circular flexure hinge is designed, which can work in the x and z axes. The mechanical characteristics of the sensing structure are analyzed theoretically. The model was established in Comsol for simulation analysisand the structure is optimized by finite element method. The hinge resonant frequency is designed as 420 Hz. The fiber Bragg grating is pasted on the surface of the hinge structure as a strain detection device, and the dynamic demodulation of FBG is realized by edge filter method. The performance of the sensor was tested with a standard shaking table. The experimental results show that the natural frequency of the sensor in x and z axes is 420 Hz, and the operating frequency range is 20−300 Hz. And the average sensitivity in the flat region is 1847.32 mV/g, the acceleration resolution is 5.41×10⁻⁴ g. The sensor demonstrated a lateral interference level of less than 5% in all two-dimensional orientations. The sensor designed in this paper is a two-dimensional vibration sensor, which is suitable for highly sensitive detection of low-frequency vibration signals, such as vibration detection of Bridges and tunnels and health monitoring of mechanical equipment.

In order to meet the needs of broad band, high diffraction efficiency and polarization independent, a double-layer trapezoidal polarization independent beam grating is proposed in this paper. Firstly, based on the strict coupled wave theory, a design model of polarimetric independent combined beam grating based on particle swarm optimization algorithm is established, and the efficiency characteristics are optimized by randomly generating characteristic wavelengths. Then, the effects of slot depth, width ratio, side Angle and other structural parameters on the diffraction efficiency and bandwidth of single-layer and double-layer trapezoidal grating are analyzed in detail. Finally, the electric field enhancement characteristics of the two structures are analyzed and discussed. The results show that the double-layer trapezoidal polarimetric beam independent grating achieves a theoretical diffraction efficiency of more than 99% in the bandwidth range of 51 nm (1038 nm−1089 nm), and has a larger process tolerance than the traditional single-layer trapezoidal structure, which meets the bandwidth of 30 nm and the high diffraction efficiency of 98% in the tolerance range, and has lower near-field enhancement of the grating. Can have a stronger resistance to laser damage. The proposed double-layer trapezoidal grating with wide band and high diffraction efficiency can improve the output power of laser system, and has great application value in the field of laser beam combination.

Segmented mirrors co-phase error detection is one of the hot topics in current scientific research. Co-phase detection technology based on broad-band light source solves the problem of long measurement times caused by the Shackle-Hartmann method due to the low target flow rates, which improves the detection accuracy and range of piston error. However, in the application of the current broad-band algorithm, the complex environment and the presence of disturbing factors such as camera perturbations will cause the acquired circular aperture diffraction images to contain a certain amount of noise, which will lead to the correlation coefficient value being lower than the set threshold, and reduce the accuracy of the method or even make it ineffective. To tackle this problem, the paper proposes integrating an algorithm based on Denoising Convolutional Neural Network (DnCNN) into the broad-band algorithm in order to realize the control of the noise interference and retain the phase information of the far-field image. First, the circular hole diffraction image obtained using MATLAB is used as the training data for DnCNN. After the training, the images with different noise levels are imported into the trained noise reduction model to obtain the noise reduced image as well as the peak signal-to-noise ratios of the circular hole diffraction images before and after noise reduction and the structural similarity between the two and the clear and noiseless image. The results indicate that the average structural similarity between the denoised image and the ideal clear image has significantly improved compared to before processing, and this achieves an ideal denoising effect, which effectively increases the ability of broad-band algorithms to cope with the effects of high noise conditions. This study has strong theoretical significance and application value for exploring the broad-band light source algorithm for applications in practical co-phase detection environments.

Long-period fiber gratings have the advantages of small size, corrosion resistance, anti-electromagnetic interference, and high sensitivity, making them widely used in biomedicine, the power industry, and aerospace. This paper proposes a long-period fiber grating sensor based on periodic microchannels. First, a series of linear structures were etched in the cladding of a single-mode fiber by femtosecond laser micromachining. Then, the laser-modified region was selectively eroded by selective chemical etching to obtain the periodic microchannel structure. Finally, the channels were filled with polydimethylsiloxane (PDMS) to improve the spectral quality. The experimental results show that the sensor has good sensitivity in the measurement of various parameters such as temperature, stress, refractive index, and bending: it has a temperature sensitivity of −55.19 pm/°C, a strain sensitivity of −3.19 pm/με, a maximum refractive index sensitivity of 540.28 nm/RIU, and a bending sensitivity of 2.65 dB/m⁻¹. All of the measurement parameters show good linear responses. The sensor has strong application prospects in the field of precision measurement and sensing.

Solar glint is a significant factor influencing sea surface target detection. For land observation platforms, a sea surface glint suppression method based on the reconstruction of common characteristics of linearly polarized images is proposed using the polarization characteristics of glints. The proposed method uses a focal plane polarization camera to obtain four-channel linear polarized images, calculates the scene’s polarization information, and generates a glint suppression image. Based on suppressing scene glint with polarization information combined with the characteristics of linear polarization images, the light intensity components of the glint suppression image are decomposed into common and characteristic components, and new weight factors are given to obtain the reconstructed glint suppression image. The results of field polarization experiments show that the maximum relative decrease in the proportion of saturated pixels in the reconstructed glint suppression image compared to the intensity image was 79.07%, and the maximum relative increase in spatial frequency and contrast were 73.77% and 172.73%, respectively. The method proposed in this paper effectively suppresses the glint noise in the sea scene and performs well in restoring background detail information.

The development of third-generation infrared focal plane detectors allows them to respond simultaneously to two different bands of infrared radiation, and the dual-band image brings great benefits to target detection and identification. In this paper, for aerial detection applications, adopting 320×256 dual-color infrared cooled detector, a large-magnification-ratio cooled infrared dual-band zoom optical system with operating bands of 3.7−4.8 μm in the midwave and 7.7−9.5 μm in the longwave has been designed for infrared detection of targets. The optical system adopts a combination of transmissive and refractive structures to realize an optical four-field-of-view switching wide-range zoom, and in order to meet the 100% cold diaphragm efficiency, a secondary imaging mode is adopted. The four-field focal lengths of the optical system are 32 mm, 200 mm, 800 mm, and 1600 mm, and the zoom ratio is 50×. The experimental results show that the optical system is close to the diffraction limit at a modulation transfer function eigenfrequency of 17 lp/mm in each of the dual-band zoom states. The optical system has the characteristics of dual-band, large zoom ratio, large zoom range, fast switching of multiple fields of view, simple and compact structure, and high-quality imaging, which will be widely used in the security fields such as searching, reconnaissance, and so on.

Phase delay mirrors were designed and prepared to regulate femtosecond laser systems’ group-delay dispersion (GDD). This paper systematically investigates the principle of compensating group-delay dispersion by phase-delay mirrors. Nb₂O₅ and SiO₂ were used as the materials with high and low refractive indices. The group-delay dispersion curves were smoothed out by pairing the phase-delay mirrors with their complementary mirrors. The phase-delayed mirrors with phase modulation data of −800 GDD were prepared, and the reflectivity reached more than 99% in the range of 900 nm−1100 nm. The bandwidth adjustment problem of femtosecond laser systems is solved to meet the requirements of femtosecond lasers

Visual detection of sonar image is one of the important technologies in the field of resource exploration in complex waters and underwater foreign object target detection. Aiming at the problem of weak features and background information interference of small targets in sonar images, this paper proposes a weak feature confocal channel modulation algorithm for underwater sonar target detection. Firstly, in order to improve the model's ability to capture and characterize the information of weak targets, we design a weak target-specific activation strategy and introduce an a priori frame scale calibration mechanism to match the underlying semantic feature detection branch to improve the accuracy of small target detection; secondly, we apply the global information aggregation module to deeply excavate the global features of weak targets to avoid the redundant information from covering the small target's weak key features; lastly, in order to solve the problem of the traditional space pyramid Finally, in order to solve the problem of traditional spatial pyramid pooling which is easy to ignore the channel information, the confocal channel regulation pooling module is proposed to retain the effective channel domain small target information and overcome the interference of complex background information. Experiments show that the model in this paper achieves an average detection accuracy of 83.3% on nine types of weak targets in the underwater sonar dataset, which is 5.5% higher than the benchmark, among which the detection accuracy of iron bucket, human body model and cube is significantly improved by 24%, 8.6% and 7.3%, respectively, which effectively improves the problem of leakage and misdetection of weak targets in the underwater complex environment.

Aiming at the low accuracy of existing non-contact blood oxygen saturation measurement methods in dynamic head scenes, a denoising method based on improved adaptive noise complete set empirical mode decomposition and wavelet threshold is proposed to extract pulse wave signals with high signal-to-noise ratio. Firstly, in order to solve the problem of false components and mode aliasing in the early stage of decomposition and reconstruction, white Gaussian noise is added to the decomposition process to make it become an improved ICEEMDAN (ICEEMDAN), so as to reduce the residual noise in the modal components. Then, ICEEMDAN was used for mode decomposition of pulse wave signals of red and blue channels, and db8 wavelet basis function was used for 3-stage decomposition and reconstruction of components conforming to the spectrum range of blood oxygen, and the reconstructed signals were used for subsequent calculation of blood oxygen value. Finally, the experimental comparison and analysis of the blood oxygen saturation results measured in different dynamic head scenes show that the average error of blood oxygen saturation obtained in different head scenes is 0.73%, which is 1.93% lower than the average error of other algorithms. The denoising method proposed in this paper has good stability in different head scenes and can meet the needs of daily blood oxygen saturation measurement.

In order to improve the detection accuracy of Doppler asymmetric spatial heterodyne (DASH) interferometer in harsh temperatures, an Opto-mechanical-thermal integration analysis was carried out. Firstly, the correlation between the interference phase and temperature is established according to the working principle and the phase algorithm of the interferometer. Secondly, the optical mechanical thermal analysis model and thermal deformation data acquisition model are designed. The deformation data of the interference module and the imaging optical system at different temperatures are given by temperature load simulation analysis, and the phase error caused by thermal deformation is obtained by fitting. Finally, based on the wind speed error caused by thermal deformation of each component, a reasonable temperature control scheme is proposed. The results show that the interference module occupies the main cause, the temperature must be controlled within 20±0.05 °C, and the temperature control should be carried out for the temperature sensitive parts, and the wind speed error caused by the part is 3.8 m/s. The thermal drift of the magnification of the imaging optical system and the thermal drift of the relative position of the imaging optical system and the detector should occupy the secondary cause, which should be controlled within 20±2 °C, and the wind speed error caused by the part is 3.05 m/s. In summary, the wind measurement error caused by interference module, imaging optical system, imaging optical system and relative position of detector can be controlled within 6.85 m/s. The analysis scheme and temperature control measures presented in this paper can provide theoretical basis for DASH interferometer engineering applications.

The photonic integrated interferometric imaging system generally adds single-mode fiber arrays at the focal plane of the subaperture, and completes the large-field-of-view splicing imaging by receiving beams with different field-of-view angles, but the direct use of fiber arrays leads to the discontinuity of the imaging field-of-view, the focal length of the subaperture becomes longer, and the thickness is increased substantially. To address the above problems, this paper proposes a combination of microlens arrays and fiber optic arrays to subdivide the subaperture image plane to achieve a seamless splicing of the field of view, and through the combination of the telephoto objective lens and the three-lens spatial compression plate significantly reduces the overall thickness of the subaperture array. The design results show that by adding 65*65 microlens array in front of the fiber array to focus the beam twice to achieve the system field of view seamless splicing, the field of view is expanded 65 times, the full field of view is 0.0489 °, the efficiency of spatial optical coupling in the center of each fiber in the single-mode fiber array is not less than 40% when the visible light is incident, and after adding the spatial compression plate to compress the free-space light path, the overall thickness of the system achieves one order of magnitude compression. The system in the realization of photonic integrated interference imaging system large field of view seamless splicing imaging at the same time, for the solution of the problem of ultra-long focal length lens thickness is too large to provide a new way of thinking.

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.

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.

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.