This PDF file contains the front matter associated with SPIE Proceedings Volume 13496, including the Title Page, Copyright information, Table of Contents, and Conference Committee information.

The in-orbit defocus of the long focal length high-resolution space optical camara has a complicated defocus variation and lasts for a long time based on cyanate resin matrix composites material optical-mechanical structure design, the camera’s refocusing decision in-orbit cannot rely on a single mode in its operational stage on orbit. Based on the theory of composite characteristics and focusing mechanism of space camera, this paper analyzes and builds the camera's in-orbit parametric defocusing model. Comprehensively considers the actual resource usage of the satellite in each stage of operation and user application requirements, a phased on-orbit refocusing strategy is studied and designed. Taking a long focal length and large aperture high-resolution camera designed of cyanate resin matrix composites material with the secondary mirror adjustment mode as an example, using focusing data in the initial in-orbit commissioning period, the defocusing model parameters were determined through fitting and optimizing, and the trend analysis and prediction of camera focus position changes were carried out according to the defocusing mathematical model. And the camera refocusing position tracking and presetting were completed based on the trend prediction during the satellite service phase, and obvious results on image quality were achieved.

The interpretation of infrared polarization image is contingent upon the accuracy of image registration. Given the inherent limitations of infrared polarization imaging, include low resolution and blurred texture details, the image registration must be robust and precise. This paper presents the results of feature point extraction and image matching experiments conducted with infrared intensity images acquired by infrared polarization imaging system with three different polarized directions: 0°, 120°, and 240°. The performances of the scale invariant feature transform(SIFT), speedup robust features (SURF) and oriented fast and rotated brief (ORB) algorithms are compared with respect to computational speed and accuracy. The results demonstrate that, in the case of large-target infrared polarization scenes, the SIFT algorithm is able to extract the greatest number of feature points and has the highest matching accuracy in comparison with the SURF and ORB algorithm. Furthermore, the ORB algorithm is the fastest in terms of computational speed, with a speed that is more than 1.5 times that of the other two algorithms. In the case of small-target infrared polarization scenes, the registration accuracy and speed of the three algorithms are comparable. The SIFT algorithm is therefore more suitable for rapid registration processing of infrared polarization of small-target scenes. It is necessary to select the most appropriate registration algorithm in accordance with the specific requirements.

A method combining multi-source input fusion-based underwater image enhancement and GAN-driven grayscale image colorization is proposed to mitigate underwater imaging interference and lighten deep learning models for better generalization and real-time performance. Firstly, spatial domain image enhancement algorithms are utilized to pre-enhance the underwater images, obtaining predictions of red information in different channels. Then, the original images and pre-enhanced images are jointly used as input images, enabling the model to access more information. This model introduces the idea of fusing and reconstructing features from different levels of multiple input images, aiming to preserve as much original information and features as possible during the image enhancement process. Finally, a generator capable of colorizing grayscale images is trained using a large dataset of color images. The quality of the output colorized images is improved by defining an objective function composed of multiple loss functions. Experimental results show that compared to commonly used methods for low-light image enhancement and colorization, this method achieves better objective evaluation results in terms of peak signal-to-noise ratio, structural similarity, scale invariant feature transform, thus verifying its excellent performance.

This paper mainly discusses the development process and breakthrough key technologies and applications of laser 3D imaging of the team, and has successively developed prototypes of real aperture 3D imaging, structured light 3D imaging, laser FLASH 3D imaging and laser polarized light 3D imaging. Research on FLASH 3D imaging gain compensation technology and 3D imaging technology based on polarized CMOS image sensor. The technical indicators realized by the prototype: the distance resolution has increased from the initial 0.3m to less than 2mm now, the image gray resolution has changed from 8*8 avalanche diode separation array to the current 1024*1024 pixel resolution CMOS image device, and the frame rate of the image is 25Fps-20kFps.

A high image quality light-small remote sensing camera design conception is proposed to satisfy the requirement of the high resolution, light weight and high image quality commercial applications. Adopting three mirrors reflection coaxial optical system, combined with light weight, high stable opto-mechanical and TDICMOS imaging circuits, is achieving the design result of 80Kg weight and 150watt power consumption. and acquires images through push-broom mode. To achieve the high SNR, the Precision Loop Heat Pipe (LHP) is adopted to keep the TDICMOS sensor operating under stable and low temperature, and the fixed pattern noise is statistically analyzed in the lab and then removed by onboard processor in real time. For MTF, Modulation Transfer Function Compensation (MTFC) algorithm is used to improve the final MTF value. The interior orientation elements stability is achieved by dedicated design of reflection mirror and its supporting structure, and indirect high precision thermal control for opto-mechanical structure. The star sensor brackets are directly mounted on the primary camera structures, meanwhile, the thermal and stiffness performance of which is specially designed to keep the exterior orientation elements stable. The final design gives the result of the 48dB for SNR, 0.15 for static MTF and high geometrical stability.

In response to the high resolution requirements of EBAPS digital low light imaging devices in military and aerospace fields, the spatial modulation transfer function is an objective method to evaluate the resolution of liner photoelectric imaging system. on the basis of the existing GaAs photocathode and CMOS structure, a five-part MTF model of EBAPS devices were constructed using modulation transfer function theory. It was proposed that the electron dispersion and scattering characteristics during electron transmission are the main factors causing the decrease in resolution. We studied the dispersion characteristics of near-field photoelectrons based on the physical model of near-field focusing. Based on the theory of low energy electron solid interaction, we combined Monte Carlo simulation methods to derive and simulate the electron transit and scattering characteristics of the passivation layer. Based on the theory of electron diffusion and drift in semiconductors, We constructed a CMOS electron transport model to analyze the electron transport diffusion characteristics. Finally, the electron dispersion and scattering mechanism of EBAPS is revealed, and the MTF model of EBAPS is established, which is composed of near-field dispersion, CMOS transport diffusion and CMOS chip. Moreover, by optimizing the proximity process parameters to realize the device preparation, the ultimate resolution of EBAPS was increased from 22lp/mm to 32lp/mm. It is pointed out that backscatter dispersion of incident electrons on the CMOS surface is a key method to further improve resolution. This has important guiding significance for the future development of high-resolution EBAPS devices.

Low-light-level (LLL) real-time color imaging technology plays an important role in military reconnaissance, scientific detection, security monitoring and assisted driving, and is one of the key technologies developed domestically and internationally. When the ambient light is insufficient, the imaging effect of the human eye is reduced. In order to enhance human eye recognition ability under low illumination and obtain imaging effects with real color, high resolution and high sensitivity, more and more teams are committed to researching LLL real-time color imaging technology. Firstly, the impact of human visual limitation and physical constraint on LLL real-time color imaging is analyzed in this paper. Then, the current research progress of LLL real-time color imaging technology is introduced. Finally, according to the future research direction, the problems and key methods that need to be further studied are proposed.

In large-scale metrology, when multiple instruments are used, the measuring field space can be large and the targets can be scattered. However, fixed-pointing distance measurement can limit flexibility. Therefore, there is an urgent need to improve automation and efficiency. This paper proposes a beam-guided laser detection module for absolute ranging that combines camera recognition and position-sensitive detection. The module uses a dual-axis fast steering mirror (FSM) driven by a compact field-programmable gate array (FPGA) to change the beam direction. The angular range for beam guiding is larger than ±20°. The mechanical structure and software are detailed introduced in the paper. This module can be directly combined with an absolute ranging system, such as frequency scanning interferometry or dual-comb ranging. It is expected that these systems will find broader applications in the industrial and geodetic survey fields.

Lidar has been widely used in Autonomous driving and robot. To accelerate the research and development of Lidar technology, test and validation is of vital important. In this work, a target simulator for Lidar is designed and demonstrated. Mainly two functions are realized including distance and environmental attenuation simulation. For the distance simulation, the time-of-flight (ToR) method is introduced and a cascaded optical delay module is designed to generate an optical delay from 2ns to up to 4μs with a step as low as 40ps, corresponding to the simulated distance from nearly zero to more than 500m. For the environmental attenuation simulation, the various factors that may influence the backscattered power are analyzed and the relationship between the factors and loss is established. A commercial Lidar is tested using the target simulator and the result shows good consistence with the result obtained using reflector panel. Also the main challenge and further solution is discussed for the optimization of the target simulator.

With the advent of the 5G era, there is an increasing demand for high-speed and high-capacity information transmission technology. Multi-wavelength Brillouin fiber lasers (MBFL) have several advantages such as large frequency shift spacing, a wide wavelength range, narrow spectrum width, high power output, and high stability. Due to these advantages, MBFL have a wide range of applications in optical communication, optical fiber sensing, lidar, and optical measurement. MBFL with multiple Brillouin frequency shift spacing have emerged the preferred light source for high-capacity dense wavelength division multiplexing (DWDM) systems. However, the narrow frequency spacing of Brillouin frequency shift makes demultiplexing difficult. To address this issue, this article reviews the latest progress in the research on MBFL. This includes MBFL with multiple Brillouin frequency shift spacing, as well as MBFL with switchable frequency shift spacing. The frequency shift spacing range covered in this article is 10GHz to 60GHz. Furthermore, the article provides a detailed introduction to the applications of MBFL in temperature sensors and microwave photons. Finally, the challenges of future development of MBFL are summarized, which how to achieve more practical lasers, such as wider frequency shift intervals, higher power, and higher signal-to-noise ratio.

NbSe₂, serving as a 2D metal electrode, has been proven to form a Schottky heterojunction with MoSe₂ to realize a highperformance broadband photodetector. Here, we further investigated the effect of gate voltage on the optoelectronic characteristics of the device. The results revealed that NbSe₂ exhibits a weak electrostatic screening effect similar to graphene, and due to the high-quality contact between the 2D metal and semiconductor, the rectification ratio of the device can be significantly modulated from 0.32 to 5.5×10⁴. Regarding the photovoltaic response characteristics of the device, the gate voltage similarly achieves significant modulation of the short-circuit current (20 nA-1.6 μA), open-circuit voltage (0-0.32 V), maximum electrical power (0-210 nW). Furthermore, the response speed of the device is also influenced by the gate voltage. This work demonstrates that Schottky heterojunctions constructed based on 2D metals can achieve effective control of optoelectronic properties, and has encouraging prospects in the fields of optical communications, optical sensing, and imaging.

Explosive fireballs generate high temperature, high pressure, and strong shock waves during the combustion process, and accurate measurement of their temperature is crucial in engineering applications. Multi spectral radiation temperature measurement technology, as an efficient non-contact detection method, has significant advantages. This study conducted temperature calibration experiments on a multispectral temperature measurement system using a 25 channel multispectral camera and a standard medium temperature blackbody furnace, and processed the calibrated grayscale images using a fully connected neural network. Generate a high-precision temperature distribution map by inputting grayscale images at 25 wavelengths into the network. This method not only improves the accuracy of temperature measurement, but also lays the experimental foundation for subsequent measurement of explosion temperature field. The research results provide key technical support for temperature measurement in engineering applications and are expected to play an important role in related fields.

In this paper, an all-fiber dual-parameter sensor based on reflective Lyot filter (RLF) and fiber Bragg gating (FBG) structure is proposed and demonstrated for simultaneous measurement of temperature and strain. The RLF consists of an in-line polarizer and a polarization maintaining (PM) reflector, and then an FBG is fused in front of the RLF to compose the reflective sensing head. Due to the different wavelength responses of RLF and FBG to temperature and strain variations, simultaneous measurement of temperature and strain can be achieved using a dual-parameter matrix. Experimental results show that in the temperature range of 30-80 °C, the temperature sensitivities of the RLF and FBG are −1.19 nm/°C and 9.22 pm/°C, respectively. In addition, for a strain adjustment of 0-1600 με, the strain sensitivity of the RLF is 6.13 pm/με, while that of the FBG is 0.359 pm/με. Meanwhile, the regression coefficients of linear fitting are both large than 0.992, which indicated that the sensor possesses an excellent linearity. Moreover, the sensor we proposed has a large temperature and strain detection range and is simple, easy to fabricate, which demonstrating potential applications in dual-parameter detection.

Synchronous heterogeneous optical remote sensing (RS) now is marching from integrated high-dimensional optical RS to single-system hyperdimensional optical RS. The representative case includes light detection and ranging (LiDAR) – from its integration with hyperspectral imager to the cutting-edge hyperspectral LiDAR. In this process, some kinds of pseudo-hyperdimensional optical RS systems are designed in order to achieve the performance comparable to the latter. However, whether such systems can give the satisfactory results for the applications with strict requirements on accuracy is always a concern for the discipline. Aiming at this issue, we attempt to make its data quality assessment, in the case of Leica BLK360. The results show the modes of laser reflectance, RGB reflectance, and laser footprint diameter index changing along with the ranging distance increasing. As regard to the key point of data quality assessment, i.e., how to assign the reflectance amplitudes of the red-green-blue (RGB) spectral bands for each laser footprint, we compare the performance of BLK360 with that of a real-sense hyperspectral LiDAR, the prototype developed by Finnish Geospatial Research Institute. The statistical comparison indicates that the latter works better, since it is not restricted to the problem caused by image matching to laser footprint, which is generally inherent in pseudo-hyperdimensional optical RS. With such challenges in application of pseudo-hyperdimensional optical RS clarified, the necessity of stepping into the stage of hyperdimensional optical RS is highlighted.

The ocean plays an important role in the global carbon cycle. Carbon is transmitted along the food chain in the form of particulate organic carbon (POC), starting from the photosynthesis of phytoplankton. Therefore, detecting the content of POC in the ocean plays a significant role in estimating the carbon sink capacity of the ocean. With the help of LIDAR detection systems, the profile concentration information of POC in seawater can be detected based on the optical property changes caused by phytoplankton. In order to satisfy the detection requirements of a LIDAR system, a detection capability with sensitivity up to the single photon level, dynamic range of 50dB, and response bandwidth of 180MHz, the echo optical signal detection and processing system is designed combining the analog detection and photon counting detection. By means of theoretical analysis, simulation analysis and experimental analysis, the analog detection channel output signal meets the following ADC acquisition requirements, and the photon counting channel can accurately discriminate the input pulse signal accurately. This echo optical signal detection and processing system is capable of providing a signal bandwidth of 180MHz and a fixed time delay without distortion, oscillation or pulse width broadening.

Many industrial components have an unfolded structure that can form a large area of flat or bowl-shaped surfaces. These surfaces are challenging to measure accurately. Catadioptric omnidirectional vision methods, owing to their wide field of view, have emerged as viable solutions for large-scale surface 3D measurement tasks. Addressing the issue of non-stitching measurement, a compact and efficient omnidirectional vision-based method using hexagonal pyramid mirrors is proposed. Mirrors are employed to reflect images from the 360° environment into the camera. Internal and external parameters of the omnidirectional vision sensor are calibrated using a laser tracker. The proposed method enables 360° omnidirectional measurement to be completed after a single imaging, showing advantages such as high accuracy, fast speed, and compact size. Its instantaneous imaging feature enables its application in dynamic surface 3D measurement. Measurement experiments are conducted on large-scale surfaces, ultimately obtaining the 3D coordinates of the mark points on the surface. The calculation results can be used for flatness measurement and profile evaluation, demonstrating the feasibility of the proposed omnidirectional vision sensor for high-precision 3D measurement.

To comprehensively analyze and evaluate the combat effectiveness of the incoherent intense light, it is necessary to obtain the distance of the glare effect caused by incoherent intense light. Firstly, by applying the nominal ocular dazzle distance model proposed by Williamson, numerical calculations were conducted to determine the glare effect distance of intense light with an illuminance of 1.2×10⁶ lx, an aperture size of 0.42 m, and a beam divergence angle of 26 mrad. The obtained results reveal the glare effect distances of a single incoherent source under different background light levels and atmospheric visibility conditions. Secondly, based on the model proposed by Mlynczak, which involves multiple intense light sources simultaneously illuminating the human eye, the glare effect distances of multiple incoherent sources under different background brightness levels and incident angles were calculated. Finally, a sensitivity analysis was conducted to assess the impact of nine factors on the distance at which the glare effect caused by incoherent intense sources. The results indicate that factors such as background brightness, atmospheric visibility, illuminance, divergence angle and incident angle have a significant impact on the glare distance of incoherent intense light.

To achieve short-range, dynamic panoramic imaging and high-resolution visual inspection of local areas of interest (ROIs) of the inner wall of a long borehole, a panoramic camera system for rock borehole condition detection is developed. The system is capable of generating a 360° panoramic image from a single frame. This is achieved by leveraging the small focal length and the exceptionally large angle of a single fisheye lens. The system's side incorporates a high-definition camera module, enabling the system to perform high-resolution inspection of any targeted region through rotation. Furthermore, the primary structure of the camera system incorporates a self-balanced design to maintain the coherence between the optical axis and the target center. The wheel-coded counting method effectively compensates for the axial orientation information of the system. By integrating it with the overlapping field of view from adjacent frames in panoramic imaging, it becomes feasible to capture panoramic images of the inner wall of long channels. Experimental results demonstrate that the system can achieve high-resolution panoramic imaging over short distances with long channels. With the assistance of the self-balanced structure and axial orientation module, the system provides a foundation for panoramic unwrapping of long channels. It further offers valuable quantitative data for intelligent evaluation of geotechnical holes.

In the traditional coaxial infrared television optical system, the central aperture of the infrared imaging system will be blocked by the television imaging system, which will cause obvious loss of luminous flux and decrease of diffraction limit. Because television imaging system is in the infrared channel, the infrared and television system size, configuration, performance, assembly will affect each other, which increases the design and assembly difficulty, as well as processing assembly and maintenance difficulty. In this paper, an off-axis infrared television composite optical system is designed. The infrared and television systems are decoupled from each other without interference. Two tilt lenses are added in front of the lens to correct the aberration of the television. The results show that the performance of off-axis infrared television composite optical system is better than that coaxial infrared television composite optical system.

Lead selenide telluride (PbSeTe) polycrystalline films were prepared by magnetron sputtering technique using ternary target material. The lead selenide telluride films were oxidized and iodized. The film samples were tested by the Rigaku Smartlab (grazing X-ray diffractometer) in Japan. The morphology of PbSeTe films after evaporation was observed by SEM (Geminisem 300). The Raman spectra of Pb Se telluride thin films were measured by a confocal microprobe Raman spectrometer (RENISHAW in Via Raman Microscope) and a He-Ne laser with wavelength of 514.5 nm. The infrared photoelectric characteristics of the detector made of PbSeTe thin film before and after sensitization were tested and analyzed. XRD and EDS results show that the prepared PTE films are homogeneous and compact with small grains, and no particles with clear edge profiles can be observed under scanning electron microscopy. The atomic ratio of Te, Pb and Se tends to be 5:7:7. The photoelectric performance detection results show that the sensitized device has excellent photoelectric performance, the photocurrent and response speed are improved significantly, and the fastest rise time and fall time of 980 nm can reach 38.95 microseconds and 620 microseconds, respectively, and the maximum signal-to-noise ratio is nearly 100 times. Therefore, by adjusting sputtering parameters and post-processing, PbSeTe thin film detectors with good photoelectric properties can be obtained.

With the continuous development and application of multispectral technology, multispectral cameras play an increasingly important role in the field of camouflage target reconnaissance. By simultaneously obtaining image data from different bands, they provide richer spectral information for target recognition. In the imaging requirements of high-speed dynamic scenes, fast and accurate registration of multispectral images has become a key technical issue, directly affecting the imaging quality and practicality of the system. In response to this situation, this article proposes an improved ORB image registration algorithm. Firstly, a scale pyramid is constructed and the ORB algorithm is used to extract feature points. The BEBLID descriptor is used to describe the feature points, and the nearest neighbor ratio (NNDR) algorithm is used for coarse matching; Then, based on feature point voting, an optimized geometric constraint is constructed to further optimize the feature points. The Random Sampling Consistency (RANSAC) algorithm is used to calculate the transformation matrix and obtain a high-precision transformation matrix; Finally, affine transformation is used to achieve image registration. The experimental results show that the algorithm has high registration accuracy and low registration time. Compared with traditional algorithms, the proposed algorithm has higher registration efficiency and can complete high-precision image registration while reducing image registration time.

The traditional correlation coefficient matching method can achieve good image matching results for multi-source satellite images under plain terrain conditions. However, satellite images under mountainous and other complex terrain conditions are prone to mismatches. This article proposes a global probability relaxation automatic matching algorithm that takes into account geometric constraints. Based on the correlation coefficient criterion, combined with least squares matching and coarse to fine matching strategies, the algorithm utilizes the global probability relaxation conditions considering geometric constraints to achieve high-precision matching of multi-source images. A DEM automatic extraction algorithm based on this method is designed. The results of the multi-source image matching and the automatic generation of DEM by using this method are analyzed to validate the effectiveness of the algorithm.

The article summarizes the development of PTC heaters for spacecraft, including the development of PTC materials, PTC heater design, and application analysis. PTC materials have been developed with BaTiO3 based ceramic matrix materials with a Curie point of 20 °C and sunflower acid based polymer matrix materials with a Curie point of39 ± 3 ℃; Ceramic based PTC heaters are suitable for shell structure schemes, while polymer based PTC heaters are suitable for thin film structure schemes; The fields applicable to PTC heaters include the platform part of large satellites, small satellites, and nearby space vehicles.

Due to the limited depth of field (DOF) of the camera, the background of images captured in large aperture mode is defocused and blurry, which not only results in the loss of important information in the background but also hinders the efficient reconstruction of the background regions. Usually, the super-resolution (SR) results of large aperture images are not good. Therefore, to enhance the reconstruction quality of defocused regions in large aperture images, a foreground-background separation and deblurring super-resolution (FBSDSR) method was proposed. Based on the idea of foreground-background separation processing, the large aperture image was divided into a sharp foreground region(If)and a blurry background region (Ib) according to the depth information. The end-to-end iterative filter adaptive network(IFAN) was used to deblur the background region Ib, refocus and restore an all-in-focus image. Finally, the enhanced super-resolution generative adversarial networks (Real-ESRGAN) which specializes in images SR of realistic scenes was used to process the sharp all-in-focus image. The proposed method realized high-quality reconstructions of both foreground and background of large aperture images. The experimental results demonstrated that the proposed method achieved effective reconstruction of the entire large aperture images clearly and solved the limitation of existing whole image reconstruction methods’ inability to reconstruct defocused regions of large aperture images. The quality and resolution of large aperture images were greatly improved.

In this paper, we propose using a snapshot narrow-band multi-spectral imaging system to capture the spectral images of the ocean surface and reconstruct its spectral reflectance. Specifically, a multi-spectral camera with a set of nine narrowband filters and a monochrome camera were used to capture the spectral images of the ocean surface, and the cubic spline interpolation method was used to reconstruct the spectral reflectance curves from the spectral images. In order to examine the validity of our system, the multi-spectral images of the ColorChecker cards in a light booth were captured, and the spectral reflectance curves of them were reconstructed. The experimental result shows that with the spectral range of 400 to 700 nm and the spectral interval of 10 nm, the average spectral root-mean-square error between the standard samples and the reconstructed samples is 0.0114, the average spectral similarity index between them is 95.87%, and the average CIE1976L*a*b* color difference is 2.48. Furthermore, the real experiment was conducted on the sea area of China; the spectral images of the ocean surface were captured from different zenith angles, and the spectral reflectance curves of them were reconstructed. The experimental results show that the values of spectral reflectance of the ocean surface were influenced by the imaging angles.

We present a Si-based Photodetector with a broadband and fast response based on Lead telluride (PbTe) polycrystalline films prepared by magnetron sputtering technique. The prepared PbTe films are polycrystalline and the dominant surface is (111) plane. The best films have triangular morphology. The atomic ratio of Pb/Te tends to 1:1. The photoelectric property detection results show that the films deposited at 130 W for 10 minutes at room temperature have excellent properties. The fastest rise time and fall time of near infrared band can reach 900 microseconds and 700 microseconds respectively, and the longest detection band can reach 4.1 microns.

The image intensifier is a type of low-light detector, consisting of three parts: a photocathode installed inside a high vacuum tube, an electron lens, and a fluorescent screen. Currently, there are few evaluation methods for the imaging quality of image intensifiers domestically. To further promote the rapid development of micro-light night vision technology and quantitatively evaluate its imaging qualities, research on quantitative evaluation methods for image intensifiers' imaging qualities has been conducted. An image quality comparison system for image intensifiers is designed, which can adapt to install various image intensifiers with different external dimensions. Meanwhile, a control software for the image intensifiers comparison system is designed to control two image intensifiers for comparison purposes. Additionally, digital image processing techniques are used to assist observers in judging the image quality, thus effectively promoting largescale experiments on image intensifiers imaging qualities comparison. Experimental testing was respectively conducted in indoor environments with illuminance levels of 10^-3 lx and outdoor environments with illuminance levels of 10^-2 lx. Actual testing experiments have shown that the system is convenient and feasible, suitable for various indoor and outdoor scenarios. It can real-time compare the imaging qualities of different models of image intensifiers. Moreover, various evaluation indicators can assist observers in judging imaging details that are difficult for the human eye to discern. This system can provide feedback to guide further optimization of the production and manufacturing processes of image intensifiers, thus promoting the development of low-light night vision technology.

Polarization detection technology provides more information than traditional photoelectric detection, including polarization degree, polarization angle, and ellipticity angle. This technology has higher accuracy in detecting targets and identifying features. The rotating wave plate polarimeter is the most commonly used instrument for measuring the polarization state of the target. Using a rotating wave plate-type polarimeter, the calculation of the Stokes parameters can be transformed into a problem of solving a definite integral using Fourier transform demodulation. The two main error sources affecting the rotating wave plate-type polarimeter in this system are the wave plate fast-axis azimuth error and the wave plate delay amount error. A polarization error model is established to investigate the impact of the non-ideality error of the polarization element on the acquisition of the Stokes coefficients of the measured target when solving the Stokes coefficients through the numerical integration method of Romberg under full polarization. The Poincaré sphere method is used to simulate the polarization state of the measured target when only the polarization angle and elliptic deviation angle are changed, and the simulation explores the rule of change between the Stokes vector measurement error of the system and the polarization state of the measured target when there is a non-ideal error of the polarization element. The simulation results show that in the presence of only the wave plate delay amount error, the error peaks of each Stokes vector do not correspond to the same sampling order, i.e., they correspond to different polarization states; In the presence of wave plate azimuth errors only, the error peaks of each Stokes vector correspond to the same sampling order, i.e., to the same polarization state. Under the same angular error, the influence of the wave plate azimuth error on the system error is larger than that of the wave plate phase delay amount error on the system error. The research method and results can provide certain research ideas and theoretical references for the error analysis research of the rotating-wave plate type polarization imager based on the rotating-wave plate type polarization imager.

Video imaging is an emerging direction in the development of Earth observation in recent years. By utilizing the agility characteristics of satellites and combining the continuity of video observation, it can achieve continuous video tracking and observation of ground targets. It can "gaze" at a certain area, continuously observe changes in the field of view, and obtain more dynamic information about the target area than traditional Earth observation satellites through "space video recording". This video camera preprocesses the image data of CMOS sensors using FPGA internal cache, and transmits the preprocessed image data using a high-speed SERDES interface. Compared to traditional cameras, camera replacement has smaller latency, simple data flow, and large data transmission volume, with a capacity of 1280 x 1024@50fps.

Optical imaging in marine, lake, and artificial water environments all faces the issue of image degradation caused by medium absorption and scattering effects. Improving image clarity has significant application value for underwater target detection and identification. The paper proposes a method for image sharpening based on the fusion of polarized images collected simultaneously, by constructing a three-channel polarization imaging device with a non-coaxial active polarization light source. The method extracts the internal and external parameters of the imaging system through a calibration plate, and then registers the polarization image set, followed by obtaining the Stokes vectors of the 0°, 45°, and 90° polarization image sets. Subsequently, based on the scattering light physical model obtained from the polarization orthogonal method, the target image is clarified. Finally, by integrating the feature images of polarization degree and polarization angle, the enhancement of image clarity is achieved. The experimental results indicate that the method can significantly enhance the imaging contrast, restore image details, and improve the signal-to-noise ratio of the image, demonstrating promising application prospects.

Laser heterodyne detection can obtain multidimensional information such as range, velocity, and micro-vibration. However, the traditional linear detection mode using PIN and APD photodiodes faces challenges of better sensitivity, especially in remote target detection. Developments of single photon detectors (SPD) such as the GM-APD array and SNSPD array provide the foundations for more robust and sensitive detection. Photon heterodyne detection (PHD) combines the advantages of heterodyne detection and single photon detection, which can obtain target multidimensional information with high sensitivity. The PHD performance is closely related to SPD working mode, and SPD single pixel detection mode requires a long accumulation time and the maximum photon count rate (PCR) is limited due to the dead time. In this paper, we propose a GM-APD pixel unit multiplexing (GPUM) method to improve the PHD performance. Theoretical analyses are conducted including the detection probability and SNR. The influence factors of coherent efficiency, photon number, and accumulative number are discussed in detail considering the PHD waveform recovery and SNR improvement. In addition, the heterodyne detection experiments are carried out using linear detection and photon detection, and the velocity extraction performance are analyzed in detail. This research is of significance to reveal the PHD process and optimize the coherent lidar systems design.

The high-performance phototransistor based on two-dimensional materials is very attractive in integrated logic function chips and large-scale real-time optical imaging. Recently, graphene-semiconductor composite film phototransistors have already achieved ultrahigh photoconductive gain due to the strong absorption capacity of the semiconductor layer and the strong mobility of graphene. However, low absorption and high dark current limit the photoresponsivity and detective band of the graphene phototransistors. Here, we fabricate a graphene/C₆₀/Sb composite film photo transistor with a broadband response (450 nm - 1500 nm), fast response speed (20 ms) and ultrahigh peak photoresponsivity (3.927 × 10⁵ A/W). The charge transfer mechanism between layers of the device has been analyzed by adjusting Sb layer thicknesses (5 nm, 10 nm, 20 nm). In addition, we observe the positive and negative photocurrent response in the experiment and study the bidirectional response of the device by applying different gate voltages. The ultrathin phototransistor (10 - 20 nm) is compatible with the traditional CMOS and nanoimprinting process to achieve large area and high-precision array integrated devices.

Hyperspectral LiDAR, an innovative active remote sensing technology, captures both spatial and spectral information of targets. When detecting multiple targets with layered distribution, overlap of echo waveforms can occur if the target interval is less than the LiDAR signal pulse width's corresponding distance unit. This paper addresses the challenge of identifying highly overlapping echo waveforms by employing machine learning for waveform classification. The study encompasses the modeling of echo signal modulation for hierarchical target detection, experimental validation, dataset acquisition based on the model, and the application of machine learning techniques. The results indicate that the Random Forest and Support Vector Machine algorithms achieve an 85% classification accuracy for 5cm intervals and an 82% average accuracy for 1-10cm intervals, demonstrating promising prospects for machine learning in classifying LiDAR echo waveforms.

Because of the non-uniform response generated during the development of EBCMOS( Electron Bombardment Complementary Metal Oxide Semiconductor), the images with non-uniform stripe noise is outputted by EBCMOS in low light environment, which seriously reduces the imaging quality of EBCMOS and has become an urgent problem to be solved. To solve this problem, the reason of stripe noise generation is analyzed, the image processing algorithm based on least squares linear correction model is implemented on FPGA, and the experimentation is completed. According to the result of experiment, this algorithm can eliminate the stripe noise of EBCMOS, and the non-uniformity of the processed image is reduced by almost 75% compared to the pre-processed image, the correction effect is fine.

Based on the working environment and characteristics of EBAPS cameras, a theoretical analysis is conducted on the relationship between camera exposure time, bias voltage, and image brightness information. An adaptive control method based on histogram feature function is proposed and implemented in the camera. Firstly, multi-point metering is used to extract regions of interest, and variable exposure time adjustment steps and bias voltage adjustment steps are designed to reduce the system metering calculation while improving the convergence speed and stability of EBAPS camera adaptive adjustment. The experimental results show that when the light intensity varies within the range of 10^-4Lux to 100 Lux, the EBAPS camera can automatically adjust two parameters included bias voltage and exposure time, to stabilize the brightness of the output image, improve the image information entropy and the dynamic range of the camera. This method can also provide reference for subsequent image recognition and target tracking.

In complex sea environments, the signal-to-noise ratio and contrast of infrared images constantly change due to factors such as wave motion, wave reflection, changes in solar altitude angle, target distance, and uneven distribution of thermal radiation, resulting in missed and false detections in infrared ship detection. In the image, ship targets are generally present in the vicinity of the sea antenna. Therefore, by determining the position of the sea sky line, the approximate area of the ship target in the image can be determined, thereby suppressing possible interference from unrelated objects in the sky and sea outside this range and reducing the probability of false detection of infrared ship targets. And in order to solve the possible interference effects of sea clutter and clouds in traditional sea antenna extraction methods, this paper proposes a sea antenna difference extraction algorithm. By enhancing the gray vertical gradient difference between rows, the sea antenna is extracted. Compared with other typical sea antenna extraction algorithms, the accuracy of the sea antenna extraction method in this paper is improved by 7.2%. The infrared image of ships has significant noise, which is affected by the attenuation of atmospheric transmission overlong distances on the sea surface. The contrast of ship targets is low, making it difficult to directly extract ship features; Moreover, the infrared imaging of ship targets is greatly affected by factors such as season, weather, and lighting, especially in harsh weather conditions such as clouds, rain, and snow, which can seriously affect the imaging effect and make the infrared images of ships blurry. Therefore, in order to effectively achieve the detection and recognition of ship targets, this paper preprocesses the infrared images of ships before detection. An improved inverse harmonic filtering algorithm is proposed, which first adopts a gradient enhancement strategy, and then eliminates the bright spot interference of sea clutter through gamma transform and inverse harmonic filtering. This can effectively remove noise and enhance image contrast. In the infrared ship target detection algorithm method, this article improves the YOLOv4algorithm by adding a self attention module to enhance the network's detection and recognition ability for weak ship targets, and optimizes the neck structure to improve the network's recognition accuracy for ship targets of different scales. In addition, this article constructs an infrared ship image dataset generated through simulation and actual collection, which includes infrared ship images captured in different scenes, times, angles, and distances. By comparing the method proposed in this article with current mainstream detection methods through experiments, the actual detection accuracy is improved to over 90%.

Broadband photodetection is paramount for various applications like imaging and sensing, thus garnering significant attention as a research hot spot in recent years. However, it is challenging to detect infrared light at room temperature due to itslow photon energy. Here, we demonstrate a Bi₂Te₃ photothermoelectric thin film photodetector fabricated using controllable and large-scale magnetron sputtering technology. The proposed device exhibits a sensitivity exceeding 9.72 mA/W and a specific detectivity of 4.52 × 10⁸ Jones under 10.37 μm infrared light illumination at room temperature. The satisfied photoresponse observed stems from an electron temperature gradient rather than electron–hole separation. Furthermore, the Bi₂Te₃ photodetector presents high performance with high airstability, broadband spectrum photodetection from visible to the mid-infrared range. This investigation paves a way for developing high-performance photodetectors leveraging topological insulator materials endowed with remarkable thermoelectric properties.

The next generation of Earth observation on-orbit optical telescopes will provide high-resolution imaging of complex scene by using the aperture synthesis technique. Fast correction of pistons among each subaperture is the critical factor to preserve the synthetic image quality. Numerous point-spread function (PSF)-based methods have been proposed for piston detection, requiring a single star as a calibration source. When the exploration mission is similar as geological hazard monitoring and terrain landform analysis, the interference fringes that can characterize the piston will be submerged in the feature information of the complex scene, making it difficult to directly extract the pistons from the image. In this paper, by setting the non-redundant exit-pupil distribution, we innovatively construct the mathematical model of the eigenvector for extend target piston sensing, termed the frequency secondary-peak piston extraction (FSPE). Based on the polynomial fitting of piston response eigenvector, the high-precision real-time piston correction is achieved through the inverse solution of several quintic functions. The proposed method can directly use images captured by CCD detector for piston sensing without a calibration source and any other additional optics. Considering the simple operation and real-time performance of this method, we believe that it can further promote the application of synthetic aperture telescope for high-resolution Earth observation.

In computer vision tasks, various types of objects exhibit distinct characteristics in images. By learning and synthesizing the commonalities present in the training set, the neural network effectively performs tasks associated with diverse objects. However, when the training set is incomplete—specifically, when certain classes are missing—it becomes challenging for the network to learn the features of these absent classes during testing. Consequently, the coverage of the training data must be evaluated prior to training the network. This study uses synthetic aperture radar (SAR) aircraft detection as an example to illustrate the importance of evaluating dataset coverage, introduce evaluation methods, and propose solutions for incomplete dataset. Variations in SAR target features occur when the relative observation angle of SAR changes, causing changes in the brightness of the target scattering points. SAR images can exhibit significantly different characteristics even for similar targets. Based on this characteristic, the aircraft in SAR images are classified into eight angle-based classes. If the training set includes fewer than eight angle types for aircraft (at least one), the network will be unable to detect aircraft from all eight angles in the test set. To tackle potential issues arising from incomplete training sets, the following solutions are proposed: Firstly, a clustering algorithm is employed to classify the labeled data more accurately by considering the differences in the heat maps of various feature data. Next, the average heat map is extracted for each data class, overlaid, and compared with the average heat map of the complete test set to identify any missing data types. Finally, the training set is supplemented with the appropriate data based on the identified missing data types. Experimental results using partial data from the SAR-AIRcraft-1.0 dataset demonstrate the effectiveness of the proposed method.

Surface defects on optics seriously affect their service life in high-power laser system. To address this issue, repair technologies for large-aperture optics are extensively employed. However, the operation of high-power laser system generates a large number of optics requiring repair. Currently, microscopic inspection is widely used for target points classification due to its high accuracy, but it has limitations such as small field of view and low efficiency. Utilizing the OTSU algorithm and Convolutional Neural Networks (CNN), a dark-field classification model for optical surface target points has been developed. Upon conducting experiments with several network models, the ResNet model, a probability threshold of 0.998 were determined. In conclusion, the classification accuracy for defects was 99.18% and for contaminants was 90.34%. The outcomes show that target points on the surfaces of optics can be accurately classified using this method.

Optics in high-power solid-state laser devices will be damaged and adhere to contaminates on the surface during manufacturing and operation, which reduces the service life. To facilitate the positioning and recognition of the flaw （damage and contaminates） in the process of automatic repair, the dark-field flaw size calibration algorithm was studied. In this paper, a flaw size calibration model based on convolutional neural network was established. The size, exposure time, and loss function of damage and contaminate were optimized respectively. The training parameter of the damage regression model is determined to be size of less than 500μm, 30ms of exposure time and SmoothL1 loss function, and the parameter of contaminate is 0-100μm, 20ms of exposure and SmoothL1 loss function. After data balancing, the calibration precision was improved. To improve the calibration consistency of the full-size segment, a comprehensive size calibration strategy is proposed. The CNN regression algorithm is used for small size, and the pixel-level calibration algorithm is used for large size. Compared with the single regression calibration algorithm, the relative error and absolute error of the calibration results of small damage (<340μm) are reduced by 41.4% and 44.13% respectively. The relative error and absolute error of small contaminate (<85μm) are reduced by 40.26% and 30.63%.

During high-speed flight, aero-optical effects are a key factor for the image degradation (including image distortion, offset, intensity reduction and image blur) of aircraft with optical imaging systems. Effective solution for neutralizing aero-optical effects is essential to improve the performance of detection, identification and tracking of the aircraft. Conventional algorithms naturally analyse blur in the frequency domain by estimating the blur kernel of the target image and the given blurred image, which is a cumbersome process. Deep learning-based aero-degraded image restoration method aims to learn the nonlinear relationship between ideal sharp image and degraded images at the pixel level through an end-to-end architecture, which usually ignores the frequency domain information. In this paper, we propose a Cross-Frequency Fusion network (CFF-Net) for aero-degraded image restoration. Simulation results show that the network is capable of achieving high-performance aero-degraded image restoration, and the average PSNR of the restored image is improved by 8.33 dB and the average SSIM is improved by 30.70% compared to the degraded image.

In order to realize the miniaturization and low cost of infrared/laser dual-mode seeker imaging system and simplify the optical system structure, a transmission/reflection common aperture infrared/laser composite seeker optical system is designed. Firstly, the structure, overall scheme and working principle of the system are studied. The optical system uses the common aperture design at the front, and the infrared and laser signals are separated by the spectroscope at the backend to enter the respective detectors. The whole optical system shares the same receiving aperture, the structure is compact, and meets the requirements of miniaturization of the seeker. The system can not only meet the requirements of large field of view in the target searching stage, but also meet the requirements of accurate recognition and tracking of the target. Based on the design metrics and parameters, the infrared optical system and laser optical system are designed and analyzed respectively. Through the analysis of action distance, the aperture and focal length of infrared and semi-active laser subsystems are designed. Simulation results show that the transfer function MTF and optical transmittance of the infrared optical system meet the design requirements, and the spot energy, linear region and optical transmittance of the semi-active laser subsystem meet the requirements.

Improving the sensitivity of the optical detection system is of great significance for the search, discovery, and positioning of dim targets such as space debris. This paper introduces the principle of a high-sensitivity multi-apertureoptical detection technology. When implementing an actual system, the inconsistency of sub-apertures is a major factor affecting the optical detection capability. Based on the establishment of a multi-aperture detection capability model, the impact of sub-aperture inconsistency errors on detection capability is analyzed, and data simulation analysis is performed. The results show that theoretically, the signal-to-noise ratio of N sub-apertures can be enhanced by a factor of √N compared to a single aperture. When there is inconsistency in energy spot diffusion and registration errors between sub-apertures, both affect the enhancement factor of the signal-to-noise ratio. To maximize system capability, it is necessary to strictly control the inconsistency and registration errors of sub-apertures in engineering implementation.

Photodetectors capable of detecting visible, infrared, and terahertz radiation are essential components in various optoelectronic applications. Traditional semiconductor-based photodetectors are often limited in their spectral detection range by their restricted bandgap. While photodetectors utilizing black phosphorus and graphene can achieve broad-spectrum detection, these are subject to the poor environmental stability of black phosphorus and the limited light absorption capacity of graphene. Platinum ditelluride (PtTe₂), classified as a type II Dirac semimetal, exhibits exceptional properties including strong light absorption, high carrier mobility at room temperature, and a zero bandgap, making it a promising candidate for photodetection applications in the infrared and terahertz regions. In this study, large-area uniform PtTe₂ thin films were epitaxially grown using a simple tellurium-vapor transformation approach. By harnessing the wideband absorption capabilities and superior carrier mobility of PtTe₂, a PtTe₂/Si vertical heterojunction photodetector and a dual-bow-tie-type antenna enhanced THz detector were proposed, enabling the fabrication of ultrabroadband photodetectors from visible to terahertz. Through optimization of the device barrier height of the PtTe₂/Si vertical heterojunction devices, carrier interfacial diffusion in the dark was suppressed, the recombination probability of photogenerated carriers was reduced, while the rapid collection of photogenerated carriers was facilitated, resulting in a wideband response spanning from 405 to 5000 nm. To enhance the absorption rate of PtTe₂ in the THz band, a dual-bow-tie-type antenna electrode was utilized to improve the photoresponse of the device in this frequency range, leveraging the driving capability of Dirac fermions simultaneously to achieve photoresponse in the 0.1 THz band. With a carefully designed device structures, the photodetector demonstrated a high specific detectivity (6.78×108 @1310 nm, 4.4×107 @0.1 THz) and a relatively fast response speed (~ ms) across a broad spectral range. The large-area fabrication capability and high specific detectivity of the device enabled room-temperature infrared imaging applications with exceptional image clarity. This approach, compatible with CMOS processes, presents a novel design concept for high-performance room-temperature photodetector from visible to terahertz detection utilizing topological semimetal materials.

Phase-shifting interferometry (PSI) is known as a promising method for measuring surface morphology. A study of PSI-based strategy for diagnosing the surface of first mirrors in Tokamak device is in progress. However, the vibration environment of the fusion device seriously affects the measurement accuracy of PSI and solutions must be explored. This paper presents a quantitative study of the influence of vibration on measurement, along with an investigation of vibration suppression methods from the perspectives of optimizing the phase extracting algorithms and experimental parameters. To enhance the precision of phase calculation, a least-squares iterative algorithm (LSI) was utilized to derive the phase angle; to minimize the number of required interferograms, a combination of Gram-Schmidt (GS) and Least-Squares Ellipses Fitting (LSEF) was employed. Additionally, selecting an optimal exposure time for image acquisition can facilitate enhanced measurement accuracy in vibrating environments.

With the rapid development of nucleic acid molecule detection technology, nucleic acid detection devices have become a global research hotspot in recent years. This paper uses multidisciplinary fusion technology to propose a nucleic acid fluorescence detection design scheme. The device is mainly composed of a motion module and an optical system. Among them, the motion module uses an S-type variable acceleration control method to precisely control the movement of the motor. The stable and accurate operation lays the foundation for the collection of fluorescent signals; the optical system uses LED as the fluorescent excitation light source. The LED collimated uniform light path is designed. Use image stitching to stitch the collected images into a complete image for analysis. Finally, measure the operating error of the motor, the average error does not exceed 14um; simulate the fluorescence signal acquisition system and collect the image of the fluorescent film, the image fluorescence is uniform, which verifies the rationality of the fluorescence acquisition system; collects simulated samples and blank control images , Analyze the stitched images, and the results clearly distinguish the simulated samples and the control group.

Fast neutron imaging technology is widely used in diagnostic research of laser driven inertial confinement fusion, Z-Pinch driven inertial confinement fusion, and other scientific devices. In order to achieve high detection efficiency in fast neutron imaging, The key lies in the performance of the scintillation fiber array in fast neutron imaging detectors. The liquid scintillation capillary array uses glass capillaries filled with liquid scintillation, which is expected to achieve10um-level spatial resolution is the preferred choice for fast neutron imaging detector arrays. The detection efficiency of liquid scintillation capillary is closely related to its opening area ratio, and increasing the opening area ratio helps to improve the detection efficiency. Therefore, this paper conducted a series of studies on the factors that affect the opening area ratio of the array. The influence of glass material size, capillary fiber drawing process, and capillary array melt pressing process on the opening area ratio was studied through experiments. The results showed that glass material size and fiber drawing temperature are the main factors affecting the opening ratio, and the thickness of the pipe wall material cannot be too small, otherwise it can easily lead to low strength and easy damage of the fiber filaments and arrays.

A free space B92 QKD system is analyzed under fog, haze and clear atmospheric conditions. With a receiver’s DCR of 1 kcps, the maximum link lengths for fog, haze and clear atmospheric conditions are 0.9 km, 1.8 km and 2.9 km, respectively. Because all simulation data comes from commercial products, a practical QKD system working the whole day can be expected.

Atomic gravimeter based on atom interferometry has become a hotspot of quantum optics applications in recent years and shown rapid progress in static-scene measurements. Improving the adaptability on dynamic scenes is an important development direction, which calls for in-depth research on various errors caused by carrier motions. This work focuses on the error evaluation and compensation of motion-induced misalignment between the Raman laser beam and the atomic trajectory. A theoretical analysis framework is formed to investigate the atom-laser misalignment errors by considering both the inhomogeneous Raman laser intensity and wavefront phase distributions in a dynamic perspective. The influence on fringe contrast and phase shift in an atom-interferometry gravimeter is discussed. Quantitative study has been done with different motion types, motion rates as well as random motion noises. The results show oscillational decay trends of fringe contrast with the motion amplitude and the increased significance of rotationally antisymmetric Zernike terms in dynamical Raman wavefront phase shift evaluation. Strong correlations can be found between the misalignment errors and the experimental parameters. A compensation method is proposed accordingly via quickly adjusting the Raman intensity or pulse duration and comprehensive Raman wavefront characterization. Both amplitude and phase corrections are achieved. The analytical approach and results provide a practical solution for further advances of atom-interferometry under harsh motional conditions.

In this paper , a comparative analysis of electromagnetic field coupling to airborne cables within a reverberation chamber is presented. The study focuses on assessing the electromagnetic field coupling to various cables in aircraft systems, which are critical for sustaining electronic functions such as power supply, data transmission, and communication between subsystems. Reverberation chambers have become integral for electromagnetic compatibility and over-the-air testing, offering a means to simulate complex electromagnetic fields. The full-wave Monte Carlo method is employed to accurately replicate the electromagnetic environment within a reverberation chamber. Through this simulation, the induced currents on different cable types illuminated by incident waves are evaluated. The findings reveal significant disparities in induced currents, with shielded twisted pair cables exhibiting the lowest induction currents and thus demonstrating the strongest resistance to electromagnetic interference. The presence of a shielding layer substantially reduces induces current intensity compared to unshielded wires, underscoring the effectiveness of shielding in mitigating electromagnetic interference. Statistical analysis of induced currents further validates the reliability of the Monte Carlo simulation method in replicating the reverberation chamber's electromagnetic environment. The pivotal role of cable in ensuring electromagnetic compatibility and resilience against external electromagnetic interference in aircraft systems is emphasized in this study.

Electromagnetic inverse scattering problems (ISPs) have been constrained by challenges such as nonlinearity and ill-posedness. This paper introduces a learning-based electromagnetic inversion approach without iterative computation dealing with these challenges. A residual block-constructed U-shape network called TransISP is developed to address the dense pixel-level microwave imaging task. Transformer blocks are embedded as the bottleneck of the TransISP to extract the latent features of the high-contrast target. Numerical experimental results demonstrate that TransISP can effectively learn the knowledge mapping the radiative part to the total contrast and outperforms the method without transformers in the quality of inversions.

Reflective displays leveraging phase-change materials within an asymmetric Fabry-Pérot (F-P) structure are poised to revolutionize the field due to their inherent benefits, including low power consumption, superior resolution, and straightforward manufacturability. This research introduces a pioneering strategy for the assembly of an asymmetric F-P structure, harnessing the properties of high-loss, high refractive index phase-change material Ag5In5Sb60Te30, to yield reflective full-color structural colors of exceptional brightness and chromatic purity.Employing a sophisticated multilayer thin-film design, this study achieves reflectance levels for the three primary colors—red, green, and blue—exceeding ninety percent. The innovative approach allows for the dynamic adjustment of color across the visible spectrum by simply modifying the thickness of a single dielectric layer, with each color attaining a reflectance of over 85%.Capitalizing on the high refractive index of the phase-change materials, in tandem with an anti-reflective layer, the design establishes a refractive index gradient that significantly amplifies the anti-reflective effect. This results in colored structures with remarkable angular robustness, demonstrating angle insensitivity for the primary colors—red, green, and blue—exceeding 60°.This design paradigm sets a new benchmark, offering a blueprint for the utilization of phase-change materials that possess high reflectivity and absorption to create reflective full-color structural colors with unmatched brightness and purity. The device's streamlined structure and low production costs render it an attractive candidate for mass production, facilitated by conventional sputtering and spin-coating techniques. The potential applications of this technology are expansive, encompassing a spectrum of fields including micro-nano displays, reflective color filters, decorative elements, electronic reader devices, and vehicular display systems, thus heralding a new era in optoelectronic applications.

The liquid-crystal polarization optical elements (LPOEs) has captured the attention of the researchers due to its distinctive characteristics, including lightweight structure, exceptional transparency, broad bandwidth, and polarization sensitivity. Despite these attributes, LPOEs have been typically confined to the role of a combiner rather than as an aberration correction element. This limitation stems from conventional design and fabrication methods which restrict the freedom of phase function in LPOEs. To address these challenges, we propose a design and fabrication method for the freeform liquid-crystal polarization imaging optics (LPIOs) by introducing freeform surfaces during the polarization exposure and conducting joint optimization throughout the design process. A prototype AR imaging system based on freeform LPIOs validates this method, proving the potential of freeform LPIO for applications requiring optics with aberration correction and efficiency control.

Recent advances in integral imaging three-dimensional (3D) displays have been hindered by challenges such as low resolution and a narrow field of view. To overcome these limitations, a promising approach involves using multi-angle directional backlighting, which controls light direction by projecting it at specific angles onto the display panel. While this method can enhance display resolution through time multiplexing, the practicality of the system is compromised by the large size of the backlight module. To address this issue, we propose a novel design that integrates integral imaging technology with a compact directional backlight module. The innovative design incorporates holographic optical elements (HOEs) to enable multi-angle light reuse within a time-multiplexed backlight module. These specially designed and fabricated HOEs ensure that the backlight source emits collimated light rays, thus achieving a more compact form factor. Furthermore, a HOE stitching structure is introduced to accommodate larger display screens. This new design reduces the volume of the backlight module by 90% while generating three angles of collimated backlight, effectively tripling the display resolution. The integration of directed backlight module, display screen, and microlens array into a single, glasses-free 3D display system represents a significant advancement. By optimizing the design parameters of each component, this approach facilitates the development of a more compact and practical integral imaging 3D display system. This approach significantly enhances the portability and usability of integral imaging systems, paving the way for future innovations in 3D display technology.

Rotational inertial navigation system (RINS) can improve navigation accuracy and has become a standard navigation equipment on ships. In practice, multiple systems are often redundantly configured to improve reliability, which provides the basis for fault diagnosis. This paper proposes a robust fault diagnosis method based on adaptive filter for redundant single-axis RINSs. The optimized dynamic model based on geometric constraint is deduced. On this basis, an on-line monitoring method for inertial sensor biases using strong tracking filter (STF) is presented. Based on the diagnosis filter outputs, the fault diagnosis parameters are constructed using a modified Bayesian algorithm, and fault diagnosis criteria are given. In addition, for the case where the fault occurs in the azimuth gyro, a second stage fault diagnosis algorithm based on least squares is proposed. Simulations show the proposed method works well.

The existence of the end face reflection in the collimator lens seriously affects the performance of coherent Lidar based on phase-modulated continuous wave (PMCW). We present an algorithm to eliminate the end face reflection basing on its characteristic of periodic digital modulation. Ultimately, with this algorithm, the effective distance is increased to 90m when the emitted optical power is 50mw.

The current perception of smart airport runway information mainly relies on single-point sensors, resulting in the detection of blind spots and cumbersome data matching, which cannot fully reflect the overall operational status of aircraft on the runway, and it is difficult to meet the requirements of efficient operation and full-time safety of the airport runway. To address the above-mentioned deficiencies, this paper relies on the construction of Ezhou Huahu International Airport in Hubei Province, China, and uses large-scale ultra-weak FBG sensing array to perceive the runway surface information. Through these sensors, the paper achieves all-domain, full-time real-time perception, analysis, management, and representation of multi-dimensional dynamic information on airport runways. The characteristic functions of airport operation and maintenance based on large-scale ultra-weak FBG sensing array are described briefly. The airport runway management system formed by combining features and functions can reflect the status of the airport runway in real time, provide a strong guarantee for the safety and operation of the airport, and provide a reference for the construction and system construction of the airport runway in the future.

Classical space-time coding methods, such as BLAST, STTC, and STBC, are coding methods based on perfect channel state information, and are decoded by coherent detection. In order to obtain the utilization rate of high-frequency bands and the gain of spatial diversity and multiplexing. However, when the network nodes move rapidly, the periodic pilot symbol channel estimation method has a large time delay. Especially when the number of transmitting antennas is relatively large, the channel training time is highly complex, and it is difficult to meet the requirements of coding accuracy. Based on the above considerations, this paper proposes a space-time-frequency coding method based on MIMOOFDM system. Compared with space-time coding, this space-time-frequency coding method makes full use of the frequency diversity gain of the MIMO-OFDM system to improve the performance of the system.

This paper introduces an optimized design for a broadband, high-reflectivity and low-stress optical thin film for MEMS Fast Steering Mirrors (FSMs) in satellite laser communication systems. The study addresses the challenge of heat dissipation in compact MEMS FSMs, particularly under high-power laser reflection, which can lead to significant thermal stress and potential device failure. Through computation and simulation, a composite film structure is proposed, integrating a metallic film with Distributed Bragg Reflectors (DBRs) to achieve over 99.9% reflectivity at 1550nm and 98.7% at 905nm, while minimizing thermal stress and strain. The design selects SiO2 and TiO2 as the materials for the DBRs, utilizes Al2O3 as the adhesion layer, and carefully calculates the thickness of each layer to optimize performance. Computation results demonstrate a substantial reduction in thermal strain compared to pure DBRs and composite films with different materials. The design also minimizes reflectivity’s angle dependence and effectively manages temperature increase, crucial for the reliability and performance of MEMS FSMs in space applications.

In recent years, visible light communication (VLC) has gained attention as a promising solution to mitigate the scarcity of spectrum resources and channel capacity issues in 6G. Light emitting diodes (LEDs), super luminance diodes (SLDs) and laser diodes (LDs) can serve as the light sources in VLC systems. Over the years, LEDs have been widely utilized in VLC systems due to lower cost and reduced risk to human eyes. However, the LD-based VLC is becoming increasingly attractive to achieve ultra- high-speed and long-distance applications due to its advantages over LEDs and SLDs such as high modulation bandwidth, high coherence, precise beam focusing, and narrow linewidth. This paper provides a summary of the latest advances in high-speed and long-distance visible light laser communication (VLLC), with maximum data rates exceeding 500Gbps and distances up to 100m, as well as the corresponding challenges and prospects. In addition, an overview of the VLLC system is provided, including devices, modulation, signal processing, channels, and networking. This paper also introduces the design of the 50-channel wavelength division multiplexing (WDM) VLLC system achievingthe date rate over 500Gbps.

In order to solve the problems such as high power and low reliability of the underwater wireless optical communication (UWOC) systems in complex waters, this paper proposes a method of an underwater wireless optical-magnetic hybrid communication (UWOMHC) system. Combining the advantages of UWOC and underwater magnetic induction communication (UMIC), the UWOMHC can realize underwater wireless data transmission via optical signals at higher data rates in calm, clear waters, while the system ensures a stable underwater wireless link via magnetic signals at lower data rates in turbid dynamic waters. In this work, the channel of UMIC is first analyzed. Secondly, the details of the proposed UWOMHC are described. Finally, the experiments are conducted in harbor seawater to verify the feasibility of the system. According to the experimental results, the proposed UWOMHC system can be an effective solution to the challenges of near-field wireless communication in complex waters.