This PDF file contains the front matter associated with SPIE Proceedings Volume 13155, including the Title Page, Copyright information, Table of Contents, and Conference Committee information.

Compared to single aperture systems, optical synthetic aperture systems greatly improve the spatial resolution, yet still exhibit a certain degree of blurring and contrast reduction. To address this challenge, numerous image restoration methods have been proposed. Recently, instead of the conventional circular synthetic aperture, the rotating rectangular synthetic aperture (RRSA) system employs a rectangular aperture to capture a sequence of images of the same scene. The RRSA system’s foldable design and absence of common-phase adjustments confer cost and complexity benefits. The captured degraded image sequences contain information about multiple directions of the target scene, so it is necessary to use multi-frame image fusion technology to restore them. However, most conventional methods often introduce visual artifacts and require substantial computational time. In this paper, we propose a Dual-Domain Fusion Network (DDFNet), restoring multi-frame degraded images in the spatial and frequency domain and then achieving superior fusion results. DDFNet employs a nested U-Net architecture to capture local pixel-level relationships, facilitating the recovery of local features and structures from spatial domain images. In parallel, we transform the input images into the frequency domain, and utilize another nested U-Net for feature extraction on the normalized spectrum and phase, thereby improving the recovery of texture and edge information. Finally, the fusion model effectively utilizes multi-level features and contextual awareness to combine the spatial and frequency domain features, achieving high-quality fusion results of captured degraded sequence images. Extensive experiments demonstrate that our method achieves superior performance both in quantitative and qualitative assessments compared to state-of-the-art techniques.

Asymmetric spectroscopic prism of a Michelson white-light interference- microscope objective introduces additional dispersion. The tilt of a reference mirror influences the dispersion and measurement accuracy of a white-light interference-based 3D reconstruction system. In this paper, we first numerically analyzed the performances of a Michelson-type interference-microscope objective by measuring a step structure at different tilt angles of the reference mirror. It showed that the height measurement errors were within the range of ±15nm when the tilt angles were 0°, 0.13°, 0.26°, 0.39° and 0.52 ° , respectively. Finally, a self-designed 5 × interference-microscope objective was used in the white-light 3D measurement system to experimentally demonstrate the influence of reference mirror tilting on the measurement. Both experimental and simulated results are in good agreement, showing that the tilt angle of the reference mirror in a 5× Michelson interference-microscope objective should be less than 0.39° while maintaining a measurement error less than ±15nm. We believe our results can provide a theoretical study for the assembly of reference mirror in a Michelson interference-microscope objective.

To achieve high-resolution image using optical synthesis aperture telescope, it’s necessary to co-phase accurately of all the telescopes so as to reduce the effect of co-phase errors including piston error, tip/tilt error, and mapping error, etc. Though simulation analysis of the optical system, error sources can be identified and thus save time of alignment. This paper introduces the Fizeau-type Y-4 prototype under development, including the layout of the Y-4 prototype, the layout of the reflective mirrors in the delayed light paths and the beam combiner. With the optical transfer function as the evaluation index, the actual equivalent diameter of Y-4 prototype is calculated. Furthermore, the effect of polarization introduced by coating and polarization differences on the contrast of interference fringe is analyzed. At present, the installation and alignment of the prototype in laboratory have been completed, and the interference synthesis of 4 light paths has been realized. One aim of this paper is to share some experiences in optical design and detection for the development of optical synthetic aperture telescopes. Another aim is to expand these new techniques to the larger optical synthesis aperture telescope project in the future.

Optimizing the sparse basis is an effective way to enhance single-pixel imaging performance. Compressed sensing typically employs discrete wavelet basis to map signals into the wavelet domain to achieve approximate sparsity, where wavelet coefficients resemble an exponential decay form. However, in the penalty term of cost function, large lowfrequency wavelet coefficients carry higher weights, while the weights assigned to small high-frequency coefficients are much smaller. This implies that high-frequency coefficients are easily neglected in optimization and are even mistaken as noise and removed, resulting in the loss of image details.We propose an effective method that introduces a diagonal matrix W with exponentially increasing diagonal elements to balance the weights of low-frequency and high-frequency wavelet coefficients, ensuring the weights of high-frequency coefficients are ample to prevent them from being mistakenly treated as noise and discarded.For normalized images of size 256*256 with 25% sampling, proposed method are applied to several common compressed sensing algorithms for single-pixel imaging reconstruction such as L1-minimization, LASSO, and OMP. The simulation results indicate an average improvement of 1.10dB, 1.32dB, and 2.65dB in PSNR, respectively. Even in the presence of strong Gaussian noise with σ =0.2, the method can still partly enhance reconstruction performance.This research provides a novel perspective on optimizing the sparse basis and a practical approach to improving single-pixel imaging performance.

Non-line-of-sight (NLOS) imaging has been a hot research field recently. Time-of-flight-based (ToF-based) active algorithms are one of the bases for NLOS, which is also the focus of this paper. In the preliminary experiments, Filtered-back-projection (FBP), Light-cone-transformation (LCT), and F-K migration algorithms have shown some shortcomings. For instance, the performance of FBP is poor when it is applied to datasets with low spatial resolution. For objects dominated by specular reflections, LCT generates a significant amount of noise. Similarly, F-K migration produces noisy results when it is employed with low spatial resolution data. To overcome the limitations of these algorithms, we study windowed Fourier transform for NLOS imaging. Experiments are used to analyze the performance of different windowing techniques. From 2D to 3D, and from time to frequency domain, we apply Hanning windows with FBP, LCT, and F-K algorithms. The results demonstrate that, compared to time domain, the performance of an algorithm using windows in frequency domain is significantly enhanced. The reconstructions become significantly clearer. Previously unrecoverable contours are revealed. Image noise is greatly reduced. Then, we employ a set of 3D Kaiser windows with various coefficients in the frequency domain for reconstruction, as a comparison to Hanning windows. We find that the Hanning window function and Kaiser windows with β in the range from 4 to 9 best suits the NLOS imaging problem.

For the 4th generation synchrotron radiation (SR) light source, obtaining high-quality light heavily relies on the performance of the injector, which requires a high-resolution system for measuring the low-emittance and small-sized beam profile. Hence, a high-resolution beam profile measurement system for the injector of the 4th generation SR light source Hefei Advanced Light Facility (HALF) under construction is designed. This paper presents the structure of the designed beam profile measurement system, analyzes the simulation results of this system, and discusses the effect of the tilted target on the system resolution. The simulation results show that the system can achieve the resolution of 14.57 μm, the minimum resolved transverse beam size in injector is 50 μm, and the relative measurement error is only 1.12 %. The designed system provides measurements of beam profile and enhances injection efficiency for the HALF injector.

In this paper, we establish a full-physical simulation model of a time-of-flight camera for the vertical imaging ranging application scene, from the exit of light to the output of depth and gray information. Firstly, according to the prior information such as the distance of the object to be detected and the illumination power of the active light source, we determine the energy and photo-generated charge amount of a single pixel entering the imaging target of the time-of-flight camera in a certain integration time. Furthermore, according to the modulation and demodulation principle of the time-of-flight camera, the input and output optical signals are cross-correlated sampled, and we can obtain the four-phase light intensity value output by the time-of-flight camera in an integration time. Finally, we calculate the gray value and depth value for the four-phase light intensity value according to the depth measurement principle of the time-of-flight camera. Experiments show that the gray and depth values obtained by the model simulation match the actual situation, and the model has a certain universality. In practical engineering applications, the model can be used to simulate the light intensity and depth information, instead of ordinary experiments, and improve efficiency.

Fresnel zone plate (FZP) is the important imaging components of the diffraction image technology, which is regarded as an important development direction for light-weighted and large-diameter space-based telescopes. However, there are some problems need to be solved, such as band structure defects, multistage diffraction characteristics, and the wavefront aberrations. Then the diffraction efficiency of the FZP is greatly reduced, and the imaging quality of the thin film diffraction imaging system is sharply degraded. In this paper, the measurement system for diffraction efficiency of the FZP is designed and the diffraction efficiency of the FZP measurement experiment is carried out. The experimental results show that the diffraction efficiency of two-step FZP is 25.36%, and that of four-step FZP is 35.36%.

In order to study the photoelectric emission performance of distributed Bragg reflector structure on GaAs photocathodes, a reflective GaAs photocathode with a buffer layer of distributed Bragg reflector structure was designed and grown. The samples were subjected to optical property testing, chemical cleaning, high-temperature purification, and Cs/O activation. Finally, the photoelectric emission efficiency of GaAs photocathodes with distributed Bragg reflector structure was measured. By comparing with traditional reflection-mode GaAs photocathodes, it was found that the introduction of DBR structure makes the optical performance and quantum efficiency of GaAs photocathodes completely different from traditional structures. Through the reasonable design of DBR structure, the absorption efficiency of specific wavelength incident light in the photocathode body can be improved. In addition, the preparation process including cleaning and activation was implemented. Combined with improved preparation technology, the emission efficiency of the photocathode can be improved.

X-ray grids are the core components of medical imaging equipment, which can filter X-ray scattering and thus enhancing image contrast and quality. Utilizing the high-lead-equivalent cladding glass materials with excellent X-ray absorption capabilities and acid-soluble core glass materials, and combined with the microchannel plate preparation process, a twodimensional hollow-core array structure composed of high-lead-equivalent cladding glass materials was obtained, which can effectively improve the contrast and resolution of images during X-ray imaging. The results show that the twodimensional X-ray grids have good absorption of X-ray scattering, reduce fog or haze in images, improve contrast, and have better imaging quality compared with metal X-ray grids for diagnostic images. It provides a new way and support for the preparation of high-performance X-ray grids.

In the fields of astronomical observation and fluorescence microscopic imaging, the obtained image is usually degraded by blur effects and Poisson noise. In this paper, we propose a robust hybrid regularization method consisting of total variation and L0-norm of image gradients and combine it with the Poisson distribution to formulate this kind of ill-posed problem. We also propose an efficient alternately minimization algorithm based on variable splitting and Lagrange multipliers to find the optimal solution, which can transform the original problem into a regularized deconvolution problem with quadratic fidelity term and a simple convex optimization problem. In the end, we carry out experiments to prove its convergence and effectiveness, the results show that the proposed method is stable, efficient and the quality of the restored image is comparable with some state-of-the-art methods.

The biggest problem faced in the application of optical under-screen fingerprint identification technology is that the finger reflects back more light information, and the information of the fingerprint is interfered by a lot of stray signals, which i s solved by the appearance of ultra-thin under-screen fingerprint identification materials. Using high transmittance core glass and light shielding cladding glass, the preparation process of fiber optic panel is used to obtain the under-screen fingerprint identification material composed of micron-level 2D optical waveguide collimated array. The test results show that the ultra-thin under-screen fingerprint identification material has a good collimation and selection effect on the reflected light signals from the peaks and valleys of the finger, the light shielding glass absorbs the reflected light signals from the large angle, and the high transmittance core glass conducts the collimated and small-angle reflected light signals, so that a clear fingerprint image can be obtained. The development of ultra-thin under-screen fingerprint identification material provides feasible for ultra-thin 5G cell phones.

In this paper, we propose a conditional generative adversarial network (CGAN) for restoring blurred image. The design of the generator derives from classic U-net network, but to improve its expression ability, we first modify the U-net by replacing some deep layers with stacked residual modules. Furthermore, we combine the channel and spatial attention modules and embed them into the generator to force it paying more attention to important channels and blurred local space. For loss function design, we comprehensively incorporate the pixel loss, perception loss and adversarial loss to enhance the performance of the proposed CGAN. Finally, the GoPro dataset is used for training and evaluating the effectiveness of the network. The results show that the proposed CGAN can achieve restored image of very high quality which is comparable with some state of the art methods.

In cases of insufficient lighting conditions, the obtained images of optical systems usually suffer from heavy noise, which subsequently has a negative impact on tasks like image segmentation, target detection, and edge extraction. Image denoising requires preserving the integrity of original information while eliminating irrelevant data from the signal. Regularization is an effective way to improve the performance of denoising algorithms, it achieves this by introducing additional constraints to ensure stable solutions. In this paper, we propose a hybrid regularization method which is based on the weighted combination of the L0-norm and L1-norm of image gradients. In order to obtain reliable denoising results, we have also developed a highly efficient alternately minimization algorithm to solve the resulting complex optimization problem. The algorithm utilizes variable splitting and Lagrange multipliers to determine the optimal solution, effectively transforming the initial problem into a simple convex optimization problem and a quadratic optimization problem, which can be rapidly solved in frequency domain. In the end, we conducted experiments to prove the efficiency of the proposed method. The results show that it is stable, efficient and the quality of the denoised images is comparable to some state-of-the-art methods.

Non-line-of-sight(NLOS) imaging through fog has been extensively researched in the fields of optics and computer vision. However, due to the influence of strong backscattering and diffuse reflection generated by the dense fog on the temporal-spatial correlations of photons returning from the target object, the reconstruction quality of most existing methods is significantly reduced under dense fog conditions. In this study, we define the optical imaging process in a foggy environment and propose a hybrid intelligent enhancement perception(HIEP) system based on Time-of-Flight(ToF) methods and physics-driven Swin transformer(ToFormer) to eliminate scattering effects and reconstruct targets under heterogeneous fog with varying optical thickness. Furthermore, we assembled a prototype of the HIEP system and established the Active Non-Line-of-Sight Imaging Through Dense Fog(NLOSTDF) dataset to train the reconstruction network. The experimental results demonstrate that even in dense fog short-distance scenarios with an optical thickness of up to 2.5 and imaging distances less than 6 meters, our approach achieves clear imaging of the target scene, surpassing existing optical and computer vision methods.

As an increasingly mature technology in the field of remote sensing, the technology of oblique photogrammetry has already become an important means for GIS data collection, and for now, it plays an important role in new fundamental surveying and mapping in the context of real 3D China's policies. To collect the traditional terrain level and urban level surveying data, the main reliance is on a five-lens oblique camera, however, there were three main disadvantages: low flight efficiency, large number of aerial photographs, and high difficulty in post-processing. Thus, based on this background, this paper proposed a light small and high-efficiency oblique photogrammetry swing scanning imaging system, using two area array sensors, and combined with mechanical control devices to achieve wide and multi-view, high-performance imaging by controlling the swing sweep in the flight direction, and using the calibration system tools to correct GNSS/IMU and area array sensor systematic error. To test the accuracy of the results data, a verification test was implemented by actual flight, 18 check points in the field were used and the mean square error of plane position and elevation were calculated, 3D models and traditional 2D results were produced. All these results showed that this system can meet the accuracy requirements of terrain maps. At the same time, this system has the advantages of small size, light weight, and high efficiency, and greatly improve the data post-processing speed, which also can be carried on different types of flight platforms. The research results of this paper have high value for promoting high-efficient acquisition of oblique image data. It has broad application prospects in acquiring urban and terrain level oblique images. To some extent, it fills in the equipment gap of domestic swing camera, and provides high-quality data model base for the implementation of 3D China and new fundamental surveying and mapping requirement in the future.

A high resolution TDI-CCD system with measurement coding is proposed to acquiring high resolution image with the limitation that pixel size is not able to be smaller. The difficulty that enhancing the resolution alone the forward direction and its vertical direction at the same time without the changing of driving circuit and the con is solved by integrating several TDI-CCDs in a system, where each pixel of the TDI-CCD is coded by the measurement matrix. The high resolution image is reconstructed by the acquirement of each TDI-CCD and the measurement matrix in the end. The simulation shows the SSIM of the image acquired by proposed high resolution TDI-CCD system can reach beyond 0.95 in theory.

The scattering and transmission of coherent light in correlated disordered media have significant research value in fundamental physics, scattering imaging, biomedical imaging, and various other applications. Directly solving optical scattering problems in disordered media typically involves the conversion of Maxwell's equations into integral equations, which can be computationally intensive. In this paper, we propose a coherent Monte Carlo ray tracing algorithm based on the Born approximation, which can efficiently simulate coherent light transport in the disordered media and generate speckle patterns. This algorithm utilizes the Born approximation theory to calculate scattering amplitudes and cross-sections of particles and modifies classical ray tracing algorithms to handle coherence of waves. To validate the accuracy of the algorithm, we compare its results with simulations that directly solve Maxwell's equations. The numerical results show that this algorithm provides highly consistent results with accurate wave equation scattering simulations while significantly reducing computation time, demonstrating its potential for applications in computational imaging tasks.

To achieve space-based positioning and imaging detection of space debris under complex lighting and large relative motion conditions, in response to the high relative speed, high-resolution imaging, precision ranging, and positioning requirements faced by space-based optical payloads, this paper proposes a new system with active and passive fusion detection. It utilizes the advantages of multiple bands (visible, infrared, and laser), combines wavefront sensing, the control of composite axis, and super-resolution imaging technologies, and has the characteristics of high reliable target acquisition, high-precision tracking, ranging, and high-resolution imaging in complex scenes. The simulation analysis results show that the capture distance for targets with a radiance of 10W/sr is better than 100 kilometers, and for the targets at a relative motion speed of 6km/s, sub meter level imaging and ranging can be achieved. It provides reference for the space-based optical payload.

At present, the strategic adjustment of global military has a common trend. With the deepening of the exploration of China's Marine, river and groundwater resources, the military demand of territorial sea sovereignty defense is becoming increasingly urgent. The realization of underwater environment survey, target detection and positioning analysis technology has become an urgent problem to be solved in underwater equipment operation in many fields. The current underwater detection technology is mainly divided into acoustic detection and optical detection. Sound detection has small underwater attenuation, wide detection range and relatively mature technology, but its imaging target identification is difficult, real-time, and is easily subject to Marine noise interference. It is difficult to fully adapt to the needs of many underwater delivery platforms and deep-sea detection operations for high resolution imaging detection, observation and positioning. The underwater photoelectric imaging technology, it has become the necessary equipment for many underwater submersible, underwater operation system and target exploration systems. The underwater laser selected circular polarization imaging system consists of selected circular polarization imaging subsystem, underwater laser radiation source, synchronous timing control subsystem, power supply, integrated display control subsystem and sealing structure. The system mainly adopts the distance selection + polarization laser imaging method, reduces the influence of backscattering on imaging quality through the underwater circular polarization laser imaging system based on distance selection, and establishes the database of the characteristics of underwater circular polarization laser imaging; on this basis, an engineering prototype is built to provide application support for target detection, identification and industrialization.

In recent years, with the development of laser technology, lasers have provided a new way for underwater optoelectronic detection of targets. Due to the unique spectral, temporal, and spatial characteristics of lasers, blue-green lasers have a strong ability to penetrate seawater. Therefore, using blue-green lasers as light sources can significantly increase the underwater detection distance. This article takes into account the blue-green window effect of seawater, selects a 532nm solid-state pulse laser as the active light source, and selects a gated image intensifier with a gate width of nanosecond accuracy for underwater imaging.The high-power 532nm solid-state laser mainly consists of a laser, a laser power drive unit, a temperature control unit, and a beam divergence angle control unit. The laser adopts a diode pumped Nd: YAG pulse laser, with a wavelength of 532nm and adjusTab.repetition frequency. It has switch control, laser emission control, and output Pin signal. In order to ensure the best field of view, the laser divergence angle and the imaging detector reception angle are synchronously controlled in linkage.By calculating and using numerical control to maintain the divergence angle and reception angle consistent, it meets the field of view requirements and provides technical support for underwater target detection and recognition.

As the core component of the electron-bombarded active pixel sensor (EBAPS), the electron-sensitive CMOS (e-CMOS) can be prepared by thinning the surface layer of back-illuminated CMOS (BSI-CMOS), which was named electron sensitization. Due to the dramatic increase of dark current during the electron sensitization of BSI-CMOS, the signal-to-noise ratio and gain characteristics of the prepared EBAPS would be reduced. To solve this problem, this paper proposed a passivation strategy of SiO₂ grown by plasma-enhanced chemical vapor deposition (PECVD) to inhibit surface defects, and the optimal SiO₂ film thickness was explored through process optimization and electron bombardment system testing. As a result, the dark current was effectively suppressed (~50 e^-1/s/pix), and a lower electron-sensitive threshold voltage of 550V was realized. Moreover, the defect states density of SiO₂ deposited by PECVD was lower compared to Al₂O₃, which resulted from the more matched lattice coefficient of SiO₂. Finally, EBAPS based on SiO₂ passivated e-CMOS was realized, and high-quality imaging was successfully achieved at 1×10^-4lx illumination. The above results showed that the SiO₂ grown by PECVD can effectively suppress dark current at a thickness of ~5 nm, and reduce the electron-sensitive threshold voltage to 550 V, which provided technical support for the subsequent development of EBAPS devices with high gain and low noise.

Spectral information has a wide range of applications in many fields. With the proposal of compressed sensing technology, computational spectral imaging has emerged, which eliminates the complex optical components in the traditional method and dramatically improves the efficiency of spectral imaging by combining optical modulation and computational reconstruction. However, such approaches still have the disadvantages of being expensive and relying on the priori information. In this paper, we propose a spectral imaging method based on Fabry-Perot interference. Our approach is based on several filters with random transmittance. Combined with optical thin film technology, we design thinner dielectric layers to realize the construction of filters, which have unique broad-spectrum modulation properties to perceive spectral information. Compared with the existing wavelength modulation curves, our designed filters have higher transmittance and better compression effects to realize spectral reconstruction with a spectral resolution of 10 nm. Both simulation and experimental results demonstrate the effectiveness of the method used in this paper.

In recent years, the array Geiger-mode avalanche photodiode (Gm-APD) has become a research hotspot in the world due to its advantages of detection sensitivity, spatial resolution and range resolution. A set of 1064 nm laser active imaging experiment platform is built with the core device of 256×128 pixel domestic self-developed InGaAs material Gm-APD. The data of 500m and 350m targets in external field are obtained, and the three-dimensional distance image, intensity image and photon counting image are reconstructed by using single photon echo signal detection method. Through the experiment, the range resolution of the detector is 0.3m, and the contrast of the photon count intensity image are larger than the intensity image. It is proved that the self-develop array Gm-APD detector with 1064nm lase has good performance, and it can demonstrate the field laser active imaging function, which lays a good research foundation for future practical application.

Single-particle imaging (SPI) at an X-ray free electron laser (XFEL) is demonstrating its potential to support the imaging and structure determination of biological specimens at atomic resolution without the need for crystallization. According to a principle of diffraction before damage, diffraction patterns of specimens with random orientations injected to the focus of ultra-short and extremely bright XFEL can be recorded before the specimens are damaged. For a successful image reconstruction, robust algorithms are needed. So far, fast and robust reconstruction algorithms from noisy and incomplete diffraction patterns have been challenges for XFEL SPI. Here we briefly outline the workflow of SPI and discuss key challenges and corresponding approaches to both phase retrieval and orientations determination. We also give an outlook of the promising algorithms for SPI by means of machine learning or deep learning and believe that the current computational challenges of XFEL SPI can be handled by utilizing techniques of modern data processing and artificial intelligence for imaging at atomic resolution and femtosecond temporal resolution in the future.

We present an intelligent imaging platform named as AiLab, which is a type of remote comprehensive experiment environment designed on a browser-server architecture. The AiLab enables users to access the server through a network utilizing a client browser for achieving the goal of remotely controlling instruments and monitoring the security status of the experimental environment. It consists of a suit of hardware and intelligent software. Some preliminary experiments demonstrate that the AiLab has simplified the development, deployment, maintenance and use of software. The core modules of AiLab are installed on the server, only requiring the client to have a browser that can access the network, without any other restrictions on the user's hardware and operating system. Users can access the AiLab through an internet using whatever any type of browser on either mobile phone, tablet, laptop or a desktop computer, easily achieving the goal of remote control of experimental equipment. If there is a need to update or expand system functions in the future, simply update the AiLab software on the server without making any modifications to the client browser. Possible application cases of the AiLab including remote experiment platform in emergency situations such as epidemic outbreaks, automatic online diseases diagnosis in rural and remote underdeveloped areas, etc.

By placing a mask over the pupil of the optical telescope, the aperture masking technique transforms the telescope into a Fizeau interferometry telescope. Thanks to reasonable aperture configuration and baseline rotation techniques, it is possible to achieve almost the same imaging quality as a full aperture telescope. This technique has shown great potential in astrometry and astrophysics research, such as: exoplanet detection, protoplanetary disk, brown dwarf, etc. In order to verify the image restoration algorithm, we carried out binary stars observations on 1.56-m telescope. We presented the numerical simulation of aperture configuration and baseline rotation, and designed the mask and the experimental system. We select some binary stars with magnitude from 5 to 7 and angular distance from 0.2 to 2arcsec as observation targets. Combined with the short exposure observation, a two-step image restoration method is proposed, the results of high-resolution image reconstruction and angular distance measurement are verified. The above results will be applied to the first-generation Fizeau interferometry prototype at the Shanghai Astronomical Observatory (SHAO).

Lensless camera is an inventional optical imaging system that can work without a typical lens system. Usually, a lensless camera works with a mask. The mask can be an amplitude one or a phase one. Considering the cost of processing, amplitude mask is preferred for its common processing method. In this paper, we find a phenomena called ’mask degeneration’. Such a situation happens when the lensless camera works in a real scene. The realworking mask pattern is not the one designed originally, it is a composite pattern in which the mask patterns of different displacements are superimposed over one another. A simulation about the mask degeneration is operated and the simulation satisfies well with the experiment. Based on these theories, a four-zone amplitude random mask for lensless imaging systems is designed. This random mask can work well in a situation when the mask degenerates. What’s more, the final result of one shoot for the lensless camera has been enlarged to almost twice the size by composing the four zones’ output pictures.

Conventional imaging systems for correction of geometric and chromatic aberrations often use two dozen individual optical elements. In recent years, researchers have introduced computational imaging to this situation. By relaxing constraints on the front-end optical system and using algorithms for restoration on the image side it can achieve high-quality imaging. In this paper,we used single DOE (diffractive optical element) and CIT (computational imaging technology) to achieve clear imaging in the visible-band from 400nm to 700nm. In optical design, PSF (point spread function) with wavelength consistency are obtained by coding the structure height of the DOE. In image recovery, the characteristics of a large diameter of PSF proposes a multi-scale deconvolution restoration algorithm. The deconvolution smooth noise is used to the low scale, and then recover the original size to achieve image restoration. The simulation shows that the frequency of the traditional phase Fresnel diffraction lens in this band when the MTF at 0.1 is only 2.58p/mm, while this method can achieve 110p/mm under the same condition. The results prove that DOE based on computational imaging can achieve visible-band achromatic and clear imaging effects maintaining a thin and light physical structure.

Non-line-of-sight (NLOS) imaging is a technology that computes images of targets outside the camera’s field of view or behind obstacles with the help of a relay surface. In real-world scenarios, the quality of NLOS images is poor due to the random and uncertain scattering characteristics of the relay surface. The noise and scattering information are coupled, making the reconstruction of clear images difficult. Time-of-flight (TOF) camera is a kind of active 3D imaging camera with the advantages of low cost, real-time capability, and rich data. This paper explores an NLOS 3D reconstruction method based on TOF cameras. Since pure Lambert surfaces do not exist in the natural world, two common materials as the relay surfaces, polypropylene (PP) plastic and polymethyl methacrylate (PMMA) plastic sheets, were randomly employed during the reconstruction of NLOS depth images. A deep neural network model is constructed to learn the scattering features of the relay surfaces, so as to realize the separation of scattering features and target features. The scattering features model base of common materials should be established first in practical application. In the experiment, 12 plaster portraits were measured, and each of them was captured depth image by 360° rotation. Then, based on U-Net network and attention mechanism, a DU-Net deep neural network is proposed. The attention mechanism channel focused on the target information and ignoring the noisy data. After training, the network model has a good reconstruction result for the degenerated images outside the training set.

With the continuous development of new infrared optoelectronic detection methods, the computational imaging based on encoding mask has received attention due to its ability to obtain spatiotemporal synchronous multidimensional information including intensity, spectrum, and polarization. However, the research results of this technology in the infrared band are relatively scarce at present. As is well known, one of the challenges in infrared computing imaging technology is information modulation and calibration. Only by obtaining a multidimensional information calibration dictionary can subsequent system integration and information recovery be completed. This paper focuses on multi-dimensional information modulation and high-precision calibration technology, and simultaneously conducts research on optimization schemes for multi-dimensional information calibration. Finally, performance indicators are verified using speckle field autocorrelation algorithm. The simulation results indicate that the multi-dimensional information modulation and calibration technology adopted in this paper can effectively obtain the multi-dimensional information calibration dictionary, laying the foundation for the subsequent integration of infrared computing imaging systems.

AOTF (Acousto-Optic Tunable Filter) spectral imaging devices is widely utilized in remote sensing applications due to its advantages of no moving parts, rapid response, and robust reliability. TeO2 (Tellurium dioxide)-based AOTF, currently represent as the most commonly employed acousto-optic crystals owing to TeO2 excellent acousto-optic figures of merit. The effect of heat in acousto-optic devices is a persistent problem because acousto-optic interactions necessitate maintaining a specific acoustic power within the crystal. Various efforts have been applied to analyze and obtain the temperature field of acousto-optic devices. Various efforts have been applied to measurement of the temperature distribution of AOTF devices. However, there is still lack the research of accurate thermal modeling for AOTF devices. This paper presents a thermodynamic model based on finite element-based approach to simulated the thermal characteristics of AOTF device. Approach considerations include the impact of device impedance matching on actual electrical power consumption, as well as factors like acoustic anisotropy and the heating effect of the acoustic absorber. Simulation model conducted on the entire device, encompassing the shell. Experimental validation was carried out by measuring the surface temperature of AO crystals under various thermodynamic conditions.

This thesis presents a miniature interferometric system designed to realize high-precision non-contact measurements of micro- and nanostructures on samples to be tested. Traditional interferometric systems mainly use vertical scanning interferometry, which is usually limited to the measurement of small samples in laboratory scenarios. In order to meet diversified measurement needs, we have developed a compact, small and portable micro interferometry system, which consists of modules such as a light source and illumination system, an imaging system, a PZT displacement system, and a micro-reflector stylus. With this system, the vertical measurement space can be reduced to less than 1mm. We also employ algorithms such as multi-step phase shift and envelope curve fitting to achieve high precision measurements with an error of less than 1%.

Multispectral image (MSI) contains a wealth of spatial information as well as spectral information, making it useful in the application of remote sensing, medical sciences, and beyond. However, traditional scanning-based imaging method is limited to low spatial or temporal resolution. Consequently, the reconstruction of high-resolution, clean, and complete MSI serves as an initial process for the numerous applications. This paper presents a novel deep unfolding network for demosaicing spectral mosaic images obtained through multispectral filter array (MSFA) imaging sensors. Concretely, the proposed network is unfolded from an iterative optimization process into an end-to-end training network, which can efficiently integrate the MSFA-based inherent degradation model with the powerful representation capability of deep neural networks. To further improve performance, a total-variation (TV) denoiser is plugged into the proposed network. Through end-to-end training, the hyperparameters within the optimization framework and TV denoiser are jointly optimized with the parameters of the neural network. Simulation results on CAVE and WHU-OHS datasets show that the proposed method outperforms state-of-the-art methods and improves the generalization capabilities to different MSFA settings.

Underwater wireless optical communication (UWOC) is a promising technology because of its high transmission rate, low latency, and small volume advantages. Therefore, it has drawn a lot of attention for real-time underwater wireless communication (UWC), especially for large-capacity transmission under short and medium distances. In this paper, we designed a real-time UWOC system with blue/green light sources and high-sensitive multi-pixel photon counters (MPPC), which can achieve an 8-Mbps half-duplex UWOC link in a standard 50-m swimming pool. Specifically, orthogonal frequency division multiplexing (OFDM) modulation was deployed and realized using a field programmable gate array (FPGA) to complete real-time signal processing. Moreover, we have also analyzed the transmission stability under misalignment of the optical axis. Under an inclination no more than 2° for the blue-light receiver or an inclination no more than 7° for the green-light receiver, the 8-Mbps communication link was always steady, and the measured bit error ratios (BER) were both below 1×10^-4. The results reveal that the proposed scheme can be beneficial to the real deployment of UWOC.

The Segmented Planar Imaging Detector for Electro-Optical Reconnaissance (SPIDER) imaging system combines synthetic aperture technology and Photonic Integrated Circuit (PIC) technology, which can reduce the size, mass and power consumption of traditional telescopes by one to two orders of magnitude. Simultaneously, it provides an effective way for future astronomical telescopes to have both large field of view, high resolution and light weight. In order to solve the problem of unsatisfactory image restoration effect of SPIDER imaging system, this paper proposes an optimized design based on a layered multi-level odd-even arm microlens array and an image reconstruction technology based on the clean algorithm. The simulation results show that the clean reconstruction algorithm based on the odd-even arm SPIDER system proposed in this paper can increase the peak signal-to-noise ratio (PSNR) by about 39% and the structural similarity (SSIM) by about 63%, which can effectively remove the artifacts caused by the system frequency truncation.

Photonic nanojet (PNJ), which is a kind of intense beam with wavelength-level focus, has gradually attracted the attention of researchers in recent years. Since the full-width at the half of the maximum (FWHM) of the PNJ can usually exceed the diffraction limit, and the high-intensity nanojet of wavelength-level can maintain a long working distance. Therefore, the PNJ has great research value in many optical applications, such as super-resolution imaging, micro-nano optical manipulation, micro-nano structure lithography, ultra-high-density optical storage, etc. In this paper, PNJs with different characteristics are obtained by adjusting the patchy area and patchy angle. The simulation results show that the PNJ generated by the patchy microspheres not only has the characteristics of an “S” type photon hook, but also has a FWHM beyond the diffraction limit.

Phase retrieval aims at recovering phase information from intensity observation patterns and realizing the reconstruction of images, which plays an important role in computational imaging. Recently, the near-field observation and reconstruction paradigm represented by fractional Fourier phase retrieval has broken through the limitations of traditional Fourier phase retrieval and realized single-shot phasing. However, existing reconstruction algorithms are mainly based on an optimized iterative framework that requires multiple iterations and relies on both accurate forward and backward projection, and thus cannot be applied to the fractional Fourier fast algorithm that lacks inverse transformations. So it limits the possibilities of real-time imaging to some extent. To address this challenge, this paper proposes a deep unfolding network, which introduces the fast fractional Fourier transform unfolded from an optimization iteration process. Through end-to-end training, the network can correct the error due to the inaccuracy of the inverse transform, achieving fast convergence and effective reconstruction. Experimental results show that the proposed method can utilize the fast fractional Fourier transform to achieve real-time snapshot phase retrieval.

The three-dimensional wind speed and temperature in Hefei were measured using a three-dimensional ultrasonic anemometer. The turbulence kinetic energy dissipation rate ε and the temperature variance dissipation rate ε_θ were estimated using the radial second-order wind speed structure function and Yaglom's 4/3 law, respectively. The analysis of the correlation between the turbulence kinetic energy dissipation rate ε and stability indicates that ε is at its maximum when the atmosphere is in neutral conditions and decreases as the absolute value of the stability parameter |z/L| increases. C²_T is at its smallest when the atmosphere is in neutral conditions and increases as the absolute value of the stability parameter |z/L| increases. After calculation, the logarithmic correlation coefficient between ε_θ and C²_T is 0.9366.

Laser three-dimensional (3D) projection technology is a new laser application technology. The technology can be a wide range of aerospace manufacturing, 3D assembly of parts and other scenarios. Through the high-speed deflection device, the laser beam can be continuously projected at different positions on the surface of the object. Due to the Visual staying phenomenon, the circular laser beam can present the expected outline and pattern on the surface of the object, so as to realize the projection function. In this paper, we designed a laser 3D projection system based on binocular vision. It analyzes the existing system designs and system calibration methods, expounds the structure design of the laser 3D projection system based on binocular vision, and explains the workflow of the system. The system calibration experiment and the laser 3D projection experiment are also conducted, and the experimental error is analyzed. The results show that the average projection error of the system is 0.37mm at the working distance of the 1.8-2.2m, which meets the usage requirements in most scenarios

The spectral resolution of interference spectral imaging technology is difficult to improve by directly increasing the maximum OPD due to limitations such as luminous flux and system stability. Studies have shown that the Fabry-Perot interferometer (FPI) can be added as a spectral resampling element to an interference hyperspectral imager to achieve spectral super-resolution, but it is more demanding on the parameters of the FPI optical element in terms of system accuracy and stability. This paper proposes a new interferometric hyperspectral imager and FPI joint interference spectrum super-resolution method. This method uses dual interferometers to perform FPI periodic modulation of the target spectral information. Then, the high-frequency interference information displacement generated after modulation is analyzed and restored to improve the spectral resolution. Experimental results show that this method can obtain spectral super-resolution information through multi-component joint interference imaging, increasing the spectral resolution to three times, and theoretically achieving higher spectral super-resolution. The optical system of this system is compact in structure, has relatively little impact on luminous flux, system complexity and stability, and has low requirements on parameters such as FPI spacing and reflectivity. This article provides a new solution for interferometric imaging hyperspectral super-resolution technology to break through the maximum OPD limit.

Three-dimensional (3D) Structured illumination microscopy (SIM) has become one of the most commonly implemented fluorescence super-resolution modes in life sciences due to its unique advantages of wide field of view, fast imaging, and weak phototoxicity and photobleaching. However, the traditional two-dimensional (2D) SIM suffers from the "missing cone” problem, which makes it impossible to realize true three-dimensional (3D) imaging. In order to solve this problem, 3D SIM has been developed to achieve twice the resolution in both lateral and axial directions. Recently, we propose a tiled and layer-adaptive 3D SIM based on principal component analysis (PCA) to solve the computational complexity and time-consuming, local perturbation of illumination parameters, and microscope moving mechanical errors faced by 3D SIM in parameter estimation. The algorithm accelerates and improves the accuracy of transverse and axial illumination parameters, which is expected to achieve fast, iteration-free, high-precision, high-quality 3D SIM super-resolution imaging.

A full-field transmission hard X-ray microscope (TXM) with 30nm resolution was designed and its prototype was constructed. The TXM relies on a compact, high stiffness, low heat dissipation and low vibration design philosophy and utilizes Fresnel Zone plate (FZP) as imaging optics. The design of the TXM was introduced in detail, including the optical layout, the parameters of the FZP, the mechanical design of the TXM instrument. Preliminary imaging result with 52nm spatial resolution was achieved.

In order to solve the polarization-related problems of liquid crystal lenses and the leakage problems of liquid lenses, this paper proposes a fabrication method of high-performance varifocal microlens arrays based on integrated PDMS gels and parallel PZT driver. When the driving voltage of the PZT piezoelectric ceramic is changed, the surface profile of the PDMS gel in the PZT will change accordingly, resulting in the change of the focal length of the lens. Experiments show that the PDMS gel lens has good imaging quality, small distortion, and an approximately linear relationship the focal length of PDMS gel lens and the voltage applied to the PZT piezoelectric ceramic. The focal length changes from -60V to 60V is 12.6mm~219.5mm. This lens is compact, simple to make, low cost, and has good optical performance. It can be widely used in camera equipment, mobile phone cameras, tablets, drones, surveillance and other smart devices.