This PDF file contains the front matter associated with SPIE Proceedings Volume 13070, including the Title Page, Copyright information, Table of Contents, and Conference Committee information.

The grating imaging system has the advantages of high resolution, high sensitivity and strong anti-interference ability, and has been widely used in machine vision, biomedicine and imaging spectroscopy and other fields. The coherence and polarization properties of the light field have different effects on the grating imaging system. This paper studies the polarization system of the grating illuminated by partially coherent light based on the unified theory of polarization and coherence. The experiment is carried out using a sinusoidal amplitude grating of 20 lines per mm. The experimental results show that when the coherence is fixed, as the normalized intrinsic frequency of the grating increases, the second harmonic disappears, leaving only the direct current (DC) component and the first harmonic component, which is consistent with the theoretical result.

Portable optical target measurement systems have widespread applications in various fields, including mechanical manufacturing, aerospace, industrial inspection, and clinical medicine. This study aims to address the marker point matching problem in binocular measurement systems. Through image preprocessing and mathematical algorithms, we have successfully achieved robust matching of marker points with uniqueness. We first converted color images to grayscale and applied the Otsu algorithm to adaptively select a global threshold, successfully extracting marker points. Using the nearest neighbor algorithm, we simplified 28 marker points to 7. Then, we employed the k-means clustering algorithm to achieve a second fitting, obtaining marker points located on the central line of the target. With these marker points, we computed key features for describing the target pose, including the direction vector of the target’s central line and its angle with respect to the image’s x-axis. Finally, we designed different algorithm modules to successfully achieve the robust matching of marker points across 360 degrees of free postures.

After the vortex beam is transmitted in the space laser communication scene for thousands or even tens of thousands of kilometers, the spot diameter will expand to several meters or even tens of meters, and the existing detection methods that require receiving the whole spot are no longer applicable. To address this problem, this paper proposes a distributed detection scheme to identify the topological charge of the vortex beam by analyzing and processing the data received from each detector. Matlab is used to simulate the proposed scheme. The vortex beam is a Laguerre-Gaussian beam with a transmission distance of 100 km, and the simulation analysis shows that the scheme can detect Laguerre-Gaussian beams with topological charge number -3 to +3.

Currently, the dominant encoding method for computer-generated holograms is phase-only holography. The Gerchberg-Saxton (GS) algorithm is a commonly used approach for hologram generation. However, it suffers from issues such as poor convergence and low efficiency. In this paper, we introduce an iterative hologram algorithm that addresses these challenges. Our proposed algorithm divides the target object into segments with a certain degree of data redundancy. It computes the hologram iteratively, giving extra weight to each iteration. We also incorporate overlap constraints to enhance hologram quality and accelerate convergence by leveraging data redundancy. What sets our algorithm apart from others is that it varies the order in which segments are processed during iterations, resulting in different final holograms. By randomly selecting the order in each iteration, we can rapidly generate multiple diverse holograms. Importantly, objects reconstructed from these holograms exhibit consistency, allowing for the quick generation of multiple phase-only holograms that help mitigate the speckle effect.

The Four-Light-Screen is often adopted for fire dispersion measurement of small arms. Due to gravitational acceleration and the muzzle vibration are always present, leading to projectile’s velocity vector no-perpendicular to the target plane of the Four-Light-Screen, which is called the oblique incidence accordingly. The oblique incidence is violated the measurable conditions of the Four-Light-Screen measurement principle. Under the muzzle position measured in advance, the muzzle position after vibration is replaced to it. The connection between the muzzle and the coordinates measured by the Four-Light-Screen is approximated as the actual trajectory. Coordinates of oblique incidence projectiles measurement methods are proposed according to establishing the equation system between the actual trajectory equation and the four detection Light-Screen plane equations of the Four-Light-Screen. Both simulation and experimental results show that the proposed methods can measure coordinates of oblique incidence projectiles. The analysis and proposed coordinates measurement methods of oblique incidence bring much to the application of external ballistic parameters measurement of small arms.

To address the measuring requirements for ultra-large diameter and ultra-high laser energy in laser-driven inertial confinement fusion, a calorimetric method was employed for laser energy measurement. NB10 neutral absorption glass was used as the laser energy absorption material, and a temperature measurement system based on thermoelectric array was designed to establish the basic parts for laser energy measurement. Additionally, the thermal effects of pulse laser and continuous laser were simulated using finite element analysis, theoretically demonstrating the thermal effects for two forms of lasers are equivalent. Through meticulous design and testing, a apparatus was developed for calibrating laser energy meters. Measurement results indicated that the repeatability of this apparatus was better than 0.2%, capable of measurement of laser energies ranging from 300J to 11000J. This development is helpful for the research of laser-driven inertial confinement fusion.

In the field of infrared target recognition for air-to-ground surveillance, challenges such as the difficulty in collecting large-scale infrared empirical data and the reduced accuracy of target recognition in complex environments like dust and smoke have been faced. This study presents a technology scheme for simulating target imaging in the mid-wave and long-wave infrared spectra under varying concentrations of dust and smoke in terrestrial backgrounds. Additionally, an improved YOLOv8 deep learning network for target recognition, incorporating group convolution and an EMA attention mechanism, was designed. Experimental results reveal that the simulated data generated by the developed target imaging simulation technology exhibits a high degree of similarity to real-world data. Furthermore, the improved target recognition deep learning network, after undergoing transfer learning, achieved a precision rate of 82.34% and a recall rate of 90.67%. The developed infrared target imaging simulation and recognition technology provide a new technological approach for the development of deep learning network technology in target recognition for both military and civilian ground-based surveillance applications.

Ion beam has the advantages of high accuracy and little damage to components, which has been widely used in the figuring of optical components. However, in figuring, the collision between the ions with high-speed collides and the surface of the optical component will cause the temperature of the optical component to rise quickly. In order to investigate the thermal effect of the ion beam figuring, the thermal deposition model is established based on the Sigmund theory of sputtering, and the thermal power density function of the surface heat source is obtained. On this basis, taking BK7 glass as the research object, Monte Carlo method was used to obtain the total power of thermal deposition under the different incidence angle of ion beam. Then the finite element method was used to simulate the thermal effect of the ion beam figuring. The result shows that the deposition energy, maximum temperature and the maximum stress decrease with the increase of incidence angle, and the maximum stress appeared in the clamping position of fixture. The corresponding simulation result shows that comparing with the fixing fixture, the maximum stress in the optical component could be reduced more than 70% by using elastic fixture.

With the increasing demand for precision optical components with the complex surface in aerospace, nuclear engineering, medical equipment and other applications, more stringent requirements of smooth surface are put forward for precision polishing. As a non-contact polishing method, abrasive jet water polishing (AWJP) technology carries forward the advantage of micro-abrasive’s collision and erosion that available micro-level removal by low-pressure control. With other unique features like no temperature rising, high flexibility, inexpensiveness and environment-friendly process, AWJP has now become a promising polishing method for ultra-precision free-form surface optical components. In fact, the topography of rough surface affected by abrasive particles cannot be predicted precisely. It is inefficient to continuously adjust the process parameters such as jet velocity, abrasive size and impact angle through experiments to obtain the smoothest polished surface. The impact deformation form irregular abrasives should be controlled in elastic plastic deformation to avoid surface damage caused by brittle fracture. In this paper, the purpose was therefore to establish impacted surface topography model. It can simulate topography of irregular abrasives impacting original rough surface in flow field. First, the model under three-dimensional abrasive impingement was constructed by the dimension reduction method. In other words, impacted surface was simplified to consist of independent elastoplastic elements theoretically. A single abrasive particle impact deformation process was constructed by combining the Popov’s dimension reduction method with Thornton's plastic deformation model. It calculated elastoplastic deformation of a single abrasive’s effect considering abrasive size and surface morphology. The acceleration and impact depth of abrasive were figured up by displacement iteration. The deformation was updated in the current three-dimensional topography of the surface, which as the initial for the next impact calculation. Moreover, abrasive density and velocity distribution were calculated by computer hydrodynamics technology. According to them, the abrasive impact depth in each region was calculated, and then the surface morphology and roughness below the whole jet beam spot are obtained. The applicability of the surface roughness model was verified by AWJP experiments. According to model, the larger tangential velocity of abrasive particle, the smaller impact depth and the larger impact length. Different angles effect on surface topography signally. When it at 90°, the surface topography caused by the velocity stagnation zone was obviously convex, and the polishing morphology is W-shaped. In contrast, 60° presented a single pit appearance and 30° presented a double pit appearance, due to increasing abrasive tangential impact. The surface roughness to be polished by AWJP was reduced from Ra 0.4 um to Ra 0.11 um. In conclusion, a micro impacted surface topography model was established. The theoretical model and experimental results prove flexibility for abrasive jet polishing with variable parameters. Through it we can determine polishing effects of particle size and velocity on rough surfaces, and then the appropriate polishing parameters can be selected. In addition, this model can be used in various abrasive impact machining situations.

In order to achieve precision in the long-distance target track measurement of projectile trajectories, high accuracy of coordinate outputs from multiple measurement planes in the target track space is required. The dual-line array camera collimation measurement system not only ensures the accuracy of output coordinates but also simplifies the calibration process. Through a comprehensive analysis of the dual-line array camera collimation measurement system, including the principle of intersection measurement, calibration of the line array camera, and error analysis of the entire measurement system, theoretical and experimental foundations are provided for the overall system design. By analyzing the principle of intersection measurement, deriving the projectile coordinate formula, and analyzing various parameters based on the coordinate formula, the calibration method for the camera is designed. This calibration method only requires calibrating the distortion coefficients, optical axis inclination angle, and camera principal point, making the calibration process simple and efficient. After calibration, the entire intersection measurement system was subjected to simulated error analysis using MATLAB software. This analysis aimed to comprehend the magnitude and trends of error influences from various factors on the measurement of impact point coordinates, as well as the distribution of errors within the 3m×3m measurement plane. Experimental results reveal that the constructed dual-line array camera intersection measurement system performs with an x-direction accuracy better than 3.8mm and a y-direction accuracy better than 3.0mm on the 3m×3m measurement plane. The experimental coordinate measurement errors align with the results obtained from theoretical analysis.

For applications such as inertial confinement fusion and remote imaging detection, optical components need to meet the requirements of ultra smooth and low loss, and their manufacturing methods must meet the requirements of eliminating surface defects and subsurface damage. This paper mainly studies a polishing method for large-diameter optical components, which combines classical polishing with equal vacuum ionization polishing to balance polishing efficiency and removal of damaged layers. The idea of combined polishing can be extended to the comprehensive application of various polishing methods.

Using the method of double-sided polishing with oscillating and rotating upper disk, we have investigated the material removal behavior of flat fused silica. It is suggested that the material removal characteristics of the optics depend on the positon and size of the upper polishing disk. Measurements together with the kinematic model results show that the effect of the swing position and size of upper polishing disk similar to sub-aperture polishing, leading to the non-uniformity distribution of the material removal on the surface of the optic component. the surface figure errors of 0.5 wavelengths is achieved after polishing process. The efficiency and quality of double-sided polishing can be improved through changing polishing disk and swing position according to this study.

o achieve the positioning and multi-degree-of-freedom machining of rotary micro-feature structures on the five- axis motion table in the focused ion beam micro-nano machining system, a high-precision sample rotator based on worm gear drive in vacuum environment is designed. The finite element method is used to simulate and optimize the key components. After loading, the maximum deformation of the component is less than 0.2μm, and the natural frequency is more than 10000Hz, which meet the requirements of the working accuracy and strength of the component. The focused ion beam machining experiment of high aspect ratio microstructure of metal material was carried out by using this sample rotator, and the surface roughness of metal material after machining was better than 5nm. The developed sample rotator expands the processing range of focused ion beam processing system.

Visible light imaging systems have a wide range of applications, including military, aerospace and biomedical applications. Among them, the detection capability evaluation of an photoelectric imaging system is an important topic, when a photoelectric imaging system is designed, there will be an indicator to check whether the system is qualified, and its operating distance is one of the acceptance indicators for the photoelectric imaging system. When the visible light imaging system works at a greater distance, people can find the target at a further location, but at the same time, the contrast of the target on the detector will be reduced, and even the target may not be detected. So when visible light imaging system is able to identify the target contrast for the imaging system, the minimum resolvable contrast (MRC, Minimum Resolvable Contrast), where we can measure the minimum resolvable contrast of photoelectric imaging system, you can use this parameter evaluation of the performance of the system, At the same time, this parameter can be used to calculate the operating distance of the photoelectric imaging system.

We introduce a computer model for polarization-sensitive interference-based diagnostics of birefringent biological samples, focusing on a specific example, the lamella of the cornea in the eye. This diagnostic technique utilizes a modified Mach-Zehnder interferometer with adjustable phase retardation for the linearly polarized reference wave, allowing separate observation of the orthogonal linearly polarized interference signals. By analyzing the mean (dynamic) and Pancharatnam-Berry phase of object field and its amplitude components, we can derive the information about medium properties, such as birefringence and optical axis orientation. The methodology outlined in the paper has the potential to be valuable in addressing a variety of structural characterization challenges in optically anisotropic biological tissues.

In this work, the near-field method is used to measure the diameter of the mode field, which allows define not only the diameter of the mode field, but also to determine the geometric parameters of the fiber position. The method is based on measuring the diameter of the mode field at the fiber output end using focused optics, which transmits the radiation power distribution along the end of the fiber to the site of the matrix photoreceiver. The most accurate measurement results with small errors can be obtained if detectors with a large dynamic range and carefully prepared fiber ends are used. The resulting image of the mode field is filtered from the noise influence and is subject to further processing. The method of automated positioning of two photonic crystal fibers, based on the autoconvolution procedure, takes into account the angle of mutual rotation of the fibers around their longitudinal axis. This allows taking into account the structure of the mode field of the fiber during the connection process and reducing optical signal losses due to the difference in mode fields in the case of connecting identical fibers. Algorithmic and software was developed that implements the proposed method and allows automating the process of controlling the positioning of photonic crystal fibers according to the size and shape of the photonic crystal fiber mode field.

Ptychography a quantitative phase imaging technique that can simultaneously achieve high spatial resolution and large field of view. Due to the simplicity in system structure and stability in convergency, it has been applied to a variety of scenarios. However, Ptychography is limited by its data acquisition method, which cannot convert the slowly changing phase into intensity changes for detection. Moreover, in experiments, it is usually necessary to recover samples and probe at each scanning position, thus the problem of "blind ptychography" exists. In addition, high-quality ptychography reconstruction relies on accurate tracking of the scanning position, but high-precision scanning equipment is expensive and difficult to be applied in many engineering fields. In view of the above, this paper proposes a modulation ptychography (MP) solution by adding a diffuser to the ptychography system, which converts the phase retardation into the intensity information. And the diffuser, which is preset in the system, can be used as a fixed component in the system after calibration, so as to solve the problem of blind ptychography. This paper also proposes a gradient correlation position tracking algorithm, which has a sub-pixel accuracy of position tracking for the scanning with overlap rate of 85% and above, which reduces the demand of high-precision positioning system. Simulations and optical experiments carried out to demonstrate the effectiveness of the method. This work will open the way for the application of Ptychography in both fundamental and applied sciences.

In order to meet the demand for portable use of the spectrometer and improve the spectral acquisition rate, the driving circuit of the miniature fiber optic spectrometer was designed. The system uses Ibsen Photonic's FSV-101 miniature fiber optic spectrometer, which integrates the S11639-01 high sensitivity Complementary Metal-Oxide Semiconductor (CMOS) image sensor. The main control chip is Field-Programmable Gate Array (FPGA), and the analog-to-digital conversion of the CMOS output signal is performed by A/D conversion chip. The system uses FPGA to drive the CMOS timing and A/D conversion timing, and then communicates with the host computer through the serial port, transmits the spectral data to the host computer for dynamic display of the spectrum. In order to verify the overall performance of the system, laser light sources were used to conduct spectral acquisition experiments. The experimental results show that the system accurately outputs the spectral data of the light source, the spectral acquisition range is 200-1000nm, the frame rate is 111Hz, and the acquisition accuracy is 8bit, which has good practicability.

For the three-dimensional detection of surface defects on optical components, the article proposes to apply the Transport of Intensity Equation (TIE) algorithm to the scattering method in detecting the depth of defects on the surface of optical element. Firstly, a simulation model is established to simulate the scattering light distribution caused by the surface defects, and then use the TIE algorithm to obtain the phase of the surface scratch, finally the depth of the scratch is calculated by the modulation characteristics of the surface scratch on the phase. The correlation coefficient and the relative root-mean-square error are used to evaluate the effectiveness of the algorithm and compared with the Angular Spectrum iterative algorithm. Numerical simulation results show that the TIE algorithm can realize the reconstruction of the depth of defects on the surface of optical elements, and the reconstructed scratch depth has a small relative error and high reconstruction accuracy. The proposed method is flexible and fast, thus suitable for practical industrial applications.

It is necessary to obtain the surrounding information by the sensor to realize target identification and distance detection in the unmanned situational awareness task. The sensors used to collect target information can be divided into visible light band sensors such as visible light cameras and non-visible light wavelength sensors such as Light Detection and Ranging (LiDAR) from the optical characteristics. The LiDAR focuses on acquiring target distance and reflection intensity information, but the details are limited and not conducive to human observation. The visible light cameras focus on acquiring well-structured and detailed target information, but it is difficult to obtain distance information. In this paper, a target recognition method based on visible-depth image fusion for heterogeneous sensors is studied to solve the influence of environmental, spatial and heterogeneous data factors on fusion results. The fusion of point cloud images and visible light image data into visual images incorporating distance information is achieved by employing a combination of the RANSAC algorithm-based spatial line intersection method and the least squares method. And target recognition and distance detection methods based on yolov5s algorithm were studied for fusion data. Through the establishment of dataset and the training of deep learning network, the specific target identification and distance determination are realized. The results show that the specific target recognition rate of this method is greater than 94%, and the accuracy is 2mm (at 10m distance). The results of target recognition and distance determination can be directly sent to the unmanned situation awareness platform to provide a basis for its next decision.

The measurement method based on the principle of optical coherence meets many requirements for high-precision nondestructive testing in advanced integrated circuit manufacturing processes. Effectively interpreting the acquired fringe information in optical coherence measurements is an essential prerequisite for achieving precision assurance. Due to issues like spectrum aliasing, traditional structured light reconstruction techniques are limited to sub-micron pixel-level accuracy in terms of precision. This paper uses time-frequency analysis to analyze the peak envelope signal formed by white light interference. Through the measurement application and simulation of typical structures represented by stepped gratings and deep trenches in semiconductor processes, the application prospects and directions of white light scanning interferometry are discussed.

The laser attenuation device has always been an important component of the LIDT system,the attenuation adjustment ability of the laser attenuation device directly affects the performance of the testing system.The continuous attenuation device of high energy laser is achieved by combining polarization cube with rotating half wave plate,when the angle of the rotating half wave plate changes from 0° to 45°, the transmissivity of the attenuator changes from 99.9% to 0.3%.This design scheme reduces the volume of the attenuation device while achieving continuous adjustment of the transmissivity.Adopting optical devices with large aperture and high damage threshold, the maximum single pulse energy that the system can withstand is 2J@1064nm. The attenuated energy is tested by using a Ophir PE50BF-DIF-C pyroelectric energy sensor,the results show that the laser energy transmissivity can be continuously adjusted within the range of [0.3%,99.9%]. Using Beamtech China SGR20 laser, it can work stably with the power density of 2J@1064nm whose experimental results meet the design re-quirements. Compared with the traditional optical variable attenuator,this design has the advantages of large dynamic regulation range, stable attenuation and continuous regulation.

Energy flows in polychromatic fields are considered. It is shown that for fields obtained as a result of the superposition of two waves with different frequencies with an analysis time shorter than the beat period, the behavior of the characteristics of the Poynting vector and angular momentum depend on the intermodulation components of the instantaneous vector. The Stokes parameters in this case determine not the state of polarization, but rather the value of the spin angular momentum. The magnitude of the Poynting vector modulus depends on the structure of the analyzed field and for fields of general form is at a level of 20% of the value observed for a coherent wave. Computer simulation data are presented.

During the operation, when the doctor determines the position of the parathyroid gland by observing the fluorescence image, he also needs to refer to the tissues or instruments around the parathyroid gland in the image, and finally determine the position of the parathyroid gland in the tissue through repeated comparison of relative positions. In order to facilitate doctors to obtain the position of parathyroid tissue more directly in the surgical area, the design of this paper uses the projection method to carry out high-light irradiation on the surface of the tissue to make the brightness of the spot where the target is located highlight the environment, and replace the search process with the indication of highlight spot. During the operation, the doctor no longer needs to locate the parathyroid gland on the tissue in a cumbersome and inefficient way, and can quickly obtain the position of the parathyroid gland in the operative area without interrupting the operation.

In the measurement of equi-inclination and Equi-attitude parameters, the four-step phase-shifting method using white light illumination is used to obtain the principal stress direction angles within the range of [-π/2, π/2], which are consistent with the attributes. This replaces the "inconsistent" isoclinic angles in the six-step phase-shifting method, avoiding the "sawtooth-like" errors in the isoclinic line-wrapped phase map and the "distortions" in the isochromatic line-wrapped phase map. The wrapped phase maps of the isochromatic lines are processed using general unwrapping methods, such as the Goldstein branch-cut method and the quality-guided method, to obtain full-field fractional fringe order. Finally, the separation of stresses is conducted to obtain σx, σy, and τxy for the entire field. A comparison is made between the experimental processing results of a radially compressed circular disk and the theoretical values. The error in the static equilibrium check on the 7.5mm diameter section of the disk, located at a distance of 30mm from the horizontal diameter, is 2.27%, meeting the engineering accuracy requirements.

Wide dynamic guided cannonballs need to be air-aligned after firing, and the precise acquisition of their initial roll angle has been a technical difficulty in the industry. In order to solve the problem that the driveless MEMS gyroscope cannot calculate the initial roll angle on a gentle trajectory, and the attitude information obtained by solving only the crest point is too few, this paper proposes a combined measurement scheme of driveless MEMS gyroscope and accelerometer based on adaptive complementary filtering technology, and the extended Kalman filter and Hilbert transform are used to solve the attitude calculation, which can obtain comprehensive attitude information and solve the problem of gentle trajectory attitude measurement of guided projectile. Both theoretical curve analysis and experimental results analysis prove the effectiveness of the method in this paper.

Phase measurement depth for traditional digital holographic Microscopy is limited by the depth of field of the Micro-objective. In order to expand the measurement range, an expanding depth of field of three-dimensional measurement method based on digital holographic microscopy technology is proposed. Firstly, two or more digital holograms can be captured by CMOS camera when the sample is located at different focusing positions. Then, every phase will be reconstructed by angle spectrum algorithm, because every reconstructed phase includes focused phase regions and defocused phase regions, the overlapped focused region between two adjacent reconstructed phases can be recognized by feature extraction. Lastly, the whole profile of sample can be calculated by using the iterative nearest point algorithm. The experiment of micro-array lens shows the proposed method is feasible.

Three-dimensional (3D) reconstruction based on digital speckle correlation has gained widespread usage in dynamic scenarios due to its ability to achieve single-frame reconstruction. Traditional binocular speckle structured light systems often face challenges such as insufficient surface texture richness and excessive curvature, leading to limitations in the accuracy of corresponding point localization during the matching process. Furthermore, partial point cloud loss caused by varying viewpoints can impact the precision and completeness of 3D reconstruction. This paper introduces a Multiview speckle correlation-based approach for 3D reconstruction. By establishing multi-view stereo camera epipolar rectification, complex speckle matching issues are transformed into one-dimensional searches along unified epipolar lines, simplifying the matching process and enhancing efficiency. Additionally, a digital speckle correlation computational model and subpixel interpolation algorithm based on Newton-Raphson iteration are employed to realize multi-view subpixel-level corresponding point localization. Ultimately, the reconstruction point cloud data is obtained through the intersection of three-ray least squares method. Experimental results demonstrate that this method achieves higher accuracy and better model completeness in 3D data reconstruction.

Among the various methods for imaging through scattering media, the speckle autocorrelation imaging method based on optical memory effect (OME) has gained significant attention for its non-invasive single-shot imaging capability through scatter media. However, the imaging range of this method is limited by OME. This paper presents a physics-informed deep learning strategy that establishes relationships among different linearly-shift-invariant subsystems based on OME to explore the range of OME range. By leveraging the feature extraction capabilities of deep learning, the proposed approach recovers sidelobes from the speckle autocorrelation patterns of objects in several OME regions. Then, a phase retrieval algorithm is employed to achieve object reconstruction. In the future, the approach can be extended to integrate different small regions of the object plane into a big one which can be linear shift invariant.

As a method to analyze the performance of optical polarization imaging systems, Optical Transfer Matrix (OTM) enjoys some distinct advantages, such as more objective, more reliable, applicable to both small and large aberration optical systems. The OTM describes the spatial frequency transfer characteristic of the system for each Stokes parameter propagating from the object plane to the image plane. In this paper, we give a spatial frequency analysis of a polarization imaging system and use knife-edge method to characterize the OTM of polarization imaging systems. In the experiment, we detect the Stokes Parameters in each state under the illumination of six typical polarized states of spatially incoherent light, and we use the experimental results to calculate the OTM. As compared with the optical grating method, the knife-edge method can measure the OTM of polarization imaging system in real time. The performance of polarization imaging systems can be evaluated by analyzing the image with OTM. This provides technical support for the subsequent research on OTM.

In order to improve the accuracy and robustness of correlation filtering algorithm in more challenging scenarios, a target tracking algorithm based on adaptive channel sample weights is proposed in this paper. Firstly, channel attention modules are added to sample branch and search branch respectively to weight the features of each branch respectively, which can effectively improve the feature expression ability. Secondly, according to the channel weights of the two branches, we learn to fuse the weight information, interact the features of the two branches, and suppress the background information. Finally, the sample learning weights are reassigned according to the channel weights of the history frame to make more efficient use of the background information. In this paper, the OTB100 data set is used to verify the effectiveness of the improved algorithm. The area under the curve is increased by 1.6%, which proves the effectiveness of the improved algorithm.

Laser measurement technology is widely used in antenna main reflector and subreflector deformation or pose measurement. Based on the laser measurement technology, atmospheric turbulence caused by the atmospheric characteristics or the convergence effect of the antenna itself will affect the refractive index disturbance during laser propagation, which affects the accuracy of the laser measurement of the antenna deformation or pose. In order to solve the problem of laser atmospheric propagation deflection caused by atmospheric turbulence on the near-ground of a large-aperture antenna, firstly, this paper decomposes the laser atmospheric propagation path into multiple isotropic air layers, calculates the atmospheric refractive index of each air layer, obtains the atmospheric refractive index of the whole laser propagation path through curve fitting methods, and then assesses the laser deflection. Secondly, the turbulence intensity under sunny daytime and cloudy nighttime are evaluated, the laser spot position deviation is compared and analyzed, and the matching relationship among turbulence intensity, theoretical deviation of the laser spots, and actual spot deviation is obtained. Finally, the deflection of laser atmospheric propagation is fitted and calculated by measuring environmental data matched to the actual experimental data of the Nanshan 26m radio telescope antenna, which verifies the effectiveness and feasibility of the proposed method.

The two-point resolution under the illumination of partially coherent light has been discussed previously and concluded that the measurement of two-point separation depends strongly upon the coherence of the illumination. However, its polarization properties that arise from the vector nature of the electromagnetic field have been ignored in previous studies. Considering multidimensional physical optical field information in the polarized imaging system, we study the spatial resolution namely separations of two points in normalized Stokes parameters based on the unified theory of polarization and coherence. Research results show that the ratio of the measured to the true separation is not equal to unity except for particular values of the actual separation. Some interesting phenomena are found, namely that two resolvable points with certain Stokes parameters will not always be resolved for other Stokes parameters.

When light propagates in a heterogeneous object, its propagation speed and refractive index value usually change with different vibration directions. However, when light passes through a heterogeneous optical crystal from a particular direction, no birefringence occurs, and this special direction is the optical axis of the birefringent material. Presently, the traditional measurement method for determining the optical axis relies on scalar imaging, which can only characterize scalars and cannot characterize polarization. Given the anisotropy of birefringent materials, it becomes difficult to determine the optical axis and measure the surface roughness. Speckle method, as an important non-contact measurement method, has gradually become the main method for measuring surface roughness due to its advantages such as small error and easy operation. The purpose of this article is to provide a device and method, to solve the problems of measuring the optical axis and roughness of birefringent materials, simultaneously.

As a new type of imaging technology, polarization imaging technology not only has a great future within target detection, but also has unique applications in machine vision. As a natural extension to the well-known Optical Transfer Function for scalar imaging systems, we proposed a new concept referred to as Optical Transfer Matrix (OTM) to analyze the performance of polarization imaging systems. The approach of OTM describes the frequency transfer characteristic of the system for the Stokes parameters between the object plane and the image plane, revealing some distinct advantages. In this paper, we modulate the spatial frequency of the light source by means of sinusoidal grating patterns and calculate the OTM from the resulting images. We evaluate the performance of polarization imaging systems by analyzing the OTM. This provides technical support for the subsequent research on OTM.

Based on canonical transforms, we develop the space-time cross covariance from incoherent fields emitted from distant objects. We simplify the results to stress the aspects qualitatively, thereby falling short of exact quantities. Specifically, we argue that fourth order field correlations in the detector plane (the Earth) can reveal the difference in axial velocities (Stellar objects) for two – or several – unresolvable objects. Besides, we derive the angular velocity for a rotating cloud of objects with rotational axes, pointing towards the observer, as can the spatial cross covariance for a single object rotating about a transverse axis. We neglect relativistic effects and the influence of optical turbulence. The analysis resembles the ones performed for objects illuminated with a coherent field, although here the spatial coherence arises due to the extreme distances between object and observer, and the temporal coherence is facilitated by spectral filtering augmented optionally by adjusting the detector separation.

The results are applicable for radiation in a broader spectrum including microwaves and gamma radiation.

Based on the photon Doppler velocimetry technology, this paper studies high-speed targets' three-dimensional (3D) velocimetry technology, reproduces the movement trajectory of high-speed targets through 3D coordinates and broadens the photon Doppler velocimetry technology application scope. First, design the multiplexed photonic Doppler velocimetry optical path structure and analyze the multiplexed photonic Doppler velocimetry principle. Then, the target 3D velocity extraction method is studied, including the fiber optic probe's spatial arrangement and the calculated method of target motion trajectory. Finally, the detection sensitivity of velocity in the direction of the 3D coordinate axis is analyzed. In order to verify the reliability of 3D velocimetry technology, the paper is described in two parts: software simulation and experiment. MATLAB is used to simulate the principle of 3D velocimetry technology. The simulation results show that 3D velocimetry technology can be realized by processing Doppler frequency shift voltage signals. In the experimental part, the high-speed target is detected through fixed-angle optical fiber probes, and four sets of Doppler frequency shift voltage signals are collected. After data processing, the target's 3D velocity is extracted, and the target's motion trajectory is reproduced. Therefore, this paper provides an idea for reproducing the target's motion trajectory by obtaining the high-speed target's 3D velocity.

The article proposes a calibration method based on array optical signal to effectively improve the measurement accuracy of a photoelectric testing system with intersecting detection areas. According to the measurement principle of the system, the proposed calibration theory is systematically described. The aim is to map the given results in the form of vector into the time sequence. Subsequently, we develop a calibration platform whose core components are an arbitrary waveform generator and a tunable laser, and thus it can generate a set of six optical signals with an exact sequential relationship. After receiving the optical signals, some measurement results with errors are obtained by the system. Many calibration operations is performed to obtain the systematic errors, which are the statistical average of the deviation between the given results and those with errors. The results show that the comprehensive performance of the proposed calibration method is superior to that of the traditional method. In addition, the proposed calibration method relative to the traditional ones has some advantages, such as high efficiency, safety and low cost.

Fizeau interferometry is widely used to measure the surface of optical components and the wavefront aberration of optical systems due to common-path configuration, high accuracy and easy implementation. However, due to the existence of wavefront slope, when the transmission light is not perfectly perpendicular to the reflection flat (RF), the gap between the RF and the test piece will cause the reflected beam to be slightly misaligned from the transmission beam in the transmission test, which is also called beam walk-off error. If the beam walk-off error is less than 1/4 of the pixel spacing, its effects can be ignored. In this work, we will analyze the wavefront slope tolerance of 800mm aperture Fizeau interferometry and suppress it by optimizing the design of the beam expansion system, which is the key component that affects the overall wavefront slope. For the camera with 2048×2048 pixel array, the wavefront slope should be less than 9.77μrad to neglect the influence of beam walk-off error within a cavity length of 5000mm. To obtain the 800mm aperture test light, a Galilean beam expander is designed to expand and collimate the 100mm aperture light into an 800mm aperture test light. Compared with the Keplerian design, the Galilean design can decrease spherical aberration by the combination of positive and negative lenses. Tested by interferometry, the slope of the transmitted wavefront of the Galilean beam expander is 3.83μrad, which ensures the high-precision measurement.

Holograms captured by digital holographic microscopic systems that use high-coherence lasers as light sources are heavily influenced because of coherent noise. The contrast of interferograms will be affected although coherent noise can be suppressed by using short coherence light sources. This paper develops a reflective common-path digital holographic microscopy (DHM) combined with partially coherent illumination. The light is scattered by a rotating diffuser and coupled into a multimode fiber, which form into an extended light source. After passing through an imaging system, the designed blazed grating generated by spatial light modulator (SLM) works as a polarization point diffraction plate at the Fourier plane, which has a circular area playing the role of a reflective pinhole at the position corresponded to the image of the multimode fiber. Being benefit from the polarization-selective modulation property of the particular blazed grating, polarization directions of diffracted component and non-diffracted component are modulated to be orthogonal. Because of the common-path configuration, the length of the object and reference path is equal and high contrast polarization phase-shifted interferograms are captured by polarization camera. Quantitative phase images are further obtained. A resolution target and a standard step plate are measured with the proposed system. The result of the resolution target shows that the lateral resolution is 715nm at least, which is higher than the reference method and close to the diffraction limit. Otherwise, the measured height of the standard step plate is 92nm and has only 4.76% deviation from the actual height, which represents high vertical resolution.

Laser range profile proves to be an effective means for the detection and identification of distant targets. One of the most important factors that influence the characteristics of laser range profile is the speckle effect. This paper investigates the laser range profile from a cylindrical target with simi-rough surface by using computer simulation based on the Kirchhoff approximation method and laser radar-related theories. Employing a substantial number of numerical experiments, we scrutinize the impact of laser speckle on range profiles. Furthermore, by integrating the scattering properties of rough surfaces with the laser speckle effects, the effects of target surface roughness and incident laser pulse width on the statistical attributes of range profile intensity are explored. The simulation and analysis results presented in this paper offer valuable insights and guidance for the field of laser radar target detection and recognition.

It is contradictory to satisfy the high-performance infrared transmittance and electromagnetic shielding in the optical window. A design method was proposed for high electromagnetic shielding and infrared transmission on a silicon substrate. Based on the equivalent circuit model theory, the equivalent circuit model of the Cu grid was modified. The infrared antireflection film was designed to further improve the infrared transmittance of the silicon-based grid. The overall transmittance of antireflection film devices compatible with electromagnetic shielding is discussed. The Cu grid was fabricated by photolithography mask and thermal evaporation deposition technology. The results show that the modified LZ equivalent circuit model can more accurately calculate the low-frequency shielding efficiency of metal grids. The simulation shows that the grid linewidth is more likely to affect the electromagnetic shielding effectiveness than the period, and the precise structure is conducive to higher electromagnetic shielding efficiency. Considering the refractive index, stress matching and convenient preparation of the film, the film system was finally selected as Sub/HL/Air (H: ZnSe, L: BaF₂), and the design center wavelength was 3514 nm. The average transmittance of the silicon-based grid (g=550 μm, 2a=50 μm) double-sided coated with the same anti-reflection film system is 81.7 % in the 3-5 μm, which is 36.2 % higher than that of the silicon-based grid (45.5 %), with the average electromagnetic shielding efficiency unchanged (SE_avg = 24.8 dB@ 1-12 GHz).

When coherent light such as laser beam is projected on a rough target, the scattering field will exhibit random bright spots, known as speckle phenomenon. If the target is in motion, the speckle field also changes over time, and the dynamic characteristics of the speckle field contain the motion information of the target. We refer to the area around the rotation axis of the target as the polar region. In this paper, computer simulation technology is used to study the power spectrum of the dynamic speckle field in the backward and nearby areas when a laser is incident around the polar region direction. The research results indicate that there exists a direction of minimum characteristic frequency of the speckle field near the polar region. When the laser direction is deviated from the rotating axis, the minimum frequency direction is symmetric with respect to the rotation axis of the incident direction, and the minimum characteristic frequency is proportional to the magnitude of the pointing error. The method proposed in this article can be used for remote orientation of the target rotation axis.

Subwavelength structured gratings are increasingly used in new optoelectronic devices, micro-optical electromechanical systems, and other fields due to their functional diversity and large design freedom. When the characteristic size of the structure is much smaller than the wavelength of the incident light, only zero-order reflection and transmission diffraction will exist. By changing the parameter values of column width, duty cycle, and trench depth of the subwavelength structured grating, its reflectivity can be changed. In this paper, the finite difference time domain method (FDTD) and the equivalent medium theory are used to study and analyze the influence of the subwavelength structural parameters of the grating on the reflection characteristics and design an anti-reflection subwavelength structural grating with an operating wavelength of 1064nm. The simulation results show that when the grating period is 0.4μm, the duty cycle is 0.875, the groove depth is 0.23μm, and the column width is 0.35μm, the reflectivity of the subwavelength structure grating for incident light from 0° to 30° can reach 0.5%~0.7%.

Recently, lead sulfide colloidal quantum dots (PbS CQDs) have demonstrated great potential in becoming one of the promising material candidates for next-generation photodetectors. PbS CQDs provide outstanding properties including size dependent bandgap tunability, high absorption coefficient, solution processability, and multiple exciton generation effects. However, a crucial criterion for the fabrication of high-performance photodetectors is the effective surface passivation of quantum dots,which can facilitate carrier transport. Conventional solution-phase ligand exchange cannot effectively passivate the <100> facets of quantum dots, leading to an increase in deep defects and a degradation of device performance. Herein, an efficient near-infrared PbS CQDs photodetectors fabricated by using an excess PbBr2 (lead bromide) passivation process is reported. By adjusting the proportion of PbBr2 in the solution phase transition, the quality of quantum dot films have been improved. Meanwhile, the photocurrent of the detector is boosted while the dark current is suppressed. According to the research results, the photodetector exhibits excellent rectification characteristics (2.91×10²) and a high on/off ratio (1.8×10³).The external quantum efficiency (EQE) of the PbS CQDs photodetector at 980 nm reaches 30% and the responsivity can reach 0.247 A/W. In addition, the detectivity of the detector can reach 1.57×10¹⁰ Jones. These results which are obtained here should be of great values in designing advanced PbS CQDs-based near-infrared photodetectors for applications in future.

Polarization imaging technique as a simple, fast and low-cost 3D reconstruction method has many applications in the field of 3D reconstruction technology. The principle of polarization 3D reconstruction technique is based on Fresnel’s theorem in physical optics, which uses the relationship between the polarization information of the image and the surface normal of the object to reconstruct the object. Since different types of reflections on an object’s surface correspond to different polarization information and surface normal, this can lead to significant deviations for transparent objects with a variety of reflection types. Therefore, we used a method that separates the partially polarized diffuse and specular reflection components by applying a polarized industrial camera and a standard industrial camera to acquire images and combining them with a depth estimation method based on polarized images to generate a depth distribution for the surface of a transparent object with a known reflectivity. Non-transparent objects were chosen for technical validation as well as transparent objects for experimental analysis. The obtained results show that compared with the polarized 3D reconstruction method that neglects partially polarized diffuse reflections, this method can reconstruct the surface of transparent objects with sufficient accuracy and has good utility in relevant industrial production.

In this paper, we present a review of the latest results obtained in the scope of ghost imaging using auxiliary multiplex channels. The proposed methods make it possible to increase the speed of image acquisition, as well as eliminate distortions in the signal of a bucket detector. One of the most serious limitations of ghost imaging is the large number of measurements required. During the data acquisition, the optical environment where the observation object is located may change its parameters, which will negatively affect the quality of the reconstructed image. To solve these problems, it is possible to use fast spatial light modulators to set structured patterns and fast detectors. However, such equipment is not available in some spectral ranges and is not able to suppress distortions in the detected signal. In this regard, our team has proposed a number of techniques to solve the problems of a large number of measurements and non-stationarity of the optical medium in ghost imaging systems. First of all, an auxiliary polarization channel method was presented in a ghost imaging system to eliminate distortion in the signal of a bucket detector. Secondly, wavelength multiplexing methods have been proposed in the visible and terahertz wavelength ranges. These methods will make ghost imaging systems more applicable to the tasks of remote sensing and mapping of areas in various spectral ranges.

Phase compensation by principal component analysis (PCA) is a fast and fully automatic numerical technique for removing the background phase in digital holographic microscopy. However, the effectiveness of this method assumes that the object is thin and localized in small areas within the field of view. We propose a multi-step numerical method for phase compensation by PCA on objects with low signal-to-background ratio (SBR) and presence of speckle noise. We demonstrate that these conditions limit the effectiveness of the conventional phase compensation method by PCA because they introduce phase discontinuities in the first principal component. Consequently, a poor estimation of the tilt and curvature coefficients of the background phase estimate is obtained. To avoid this, we identify and remove error points in the unwrapped first principal component vectors, followed by guided adjustment of the curve-fitted coefficients to compensate for the phase jump due to phase discontinuities. The effectiveness of the proposed method was demonstrated on a simulated object wave with a known background phase, and on a reconstruction of a complex object obtained using multiple-plane phase retrieval. Results show that optimal adjustment of the curve-fitted coefficients to compensate for the phase jump leads to the best estimation of the background phase in a least-squares sense.

In this study, we present a novel approach for the measurement of modulation transfer function (MTF) of fisheye lenses. Fisheye lenses are known for their extreme wide-angle views, and pose unique challenges for MTF testing due to their complex optical properties, and the need for a large space for testing. The objective of this research is to devise a compact testing setup that enables MTF analysis of fisheye lenses within a compact controlled environment. To achieve this, we designed a setup using an adapter lens that reduces the required testing space from a full room to a compact 0.5m × 0.5m × 0.5m enclosure. We show an MTF analysis on one fisheye lens within this controlled environment.

Direct time-of-flight (dToF) Lidar system based on single photon avalanche diode (SPAD) sensor plays a key role in the range finding applications because of its high sensitivity, low power consumption and high integrity. The travel time of photons backscattered from a distant target will be measured by the time-to digital-converters (TDC) to create a histogram whose peak location indicates the target distance. However, the bin width of histogram determined by the TDC’s time resolution (LSB) limits the precision of distance measurement. Therefore, sub-bin interpolation methods are introduced to facilitate super precision on-chip distance estimation. The balance between the performance and algorithm complexity must be kept very carefully, to maintain acceptable circuit area occupied, the power consumption and yet not to severely degrade performance. In this paper, we present the experimental results obtained from single point Lidar system composing of the Hangzhou Parity’s MPX102Q SPAD sensor as the receiver and a VCSEL pulse emitter as the transmitter. Several interpolation methods like the simple centroid or center-of-mass (CM) algorithm, and the gaussian mask centroid are applied to process raw histograms. The interpolation results of different algorithms are compared with the direct peak location method to examine their performance including distance resolution and ranging accuracy in different situations. Both sub-bin depth resolution, together with high precision and accuracy (mm level) covering a range up to 15m are achieved by this sensor containing integrated circuits for sub-bin interpolation, and this sensor is with potential to benefit the price-sensitive and power-constrained consumer products like sweeping robots.

Traditional lithography techniques are currently facing challenges, including high costs and the susceptibility of mask plates to damage. This research aims to elucidate the feasibility and technical constraints of a novel diffraction lithography approach. This method can reduce the size and cost of lithography machines, break through existing technological barriers, and offer new possibilities for the future development of lithography machines.

We have built a basic computational holographic lithography system utilizing a 405nm laser and validated the system using holograms obtained with both classical GS algorithm and a newly proposed method. With the GS holograms, patterns with 700nm features have been successfully exposed on the photoresist. With our new algorithms, multiple holograms for the same target pattern can be generated with different settings in the algorithm. Sequential exposure of those holograms resulted in continuous lines 500 nm wide with reduced speckle artifacts, which was about a 1.4-time improvement over the result from the GS algorithm. Future research will focus on optimizing and enhancing the experimental system and the hologram calculation methods to reduce the line widths further and improve the exposure pattern quality.

Aiming at convenient and quick identification of parathyroid glands, a set of portable rapid identification system of parathyroid glands was developed in this paper.According to autofluorescence characteristics of parathyroid glands, fluorescence excitation and capture system was designed. The annular row arrangement of excitation light source was designed for meeting the requirements of clinical operation. An co-axial projection indicating system, including projector and dichroic mirror, were designed. The projection field of view and shooting field of view were matched and not affected by the change of the working environment The upper computer software of the system was developed based on Python and PYQT. Based on the maximum peak value and average gray level of the histogram, the algorithm of histogram equalization clipping threshold parameter was improved. Comparing the subjective feeling and objective evaluation index of the enhanced image, the fluorescence image enhancement effect of this paper is better than that of common algorithms. Simulated clinical experiments have verified that the system can distinguish parathyroid glands from muscle and adipose tissue with accuracy.

Three-dimensional measurement of transparent objects has always been a challenging task in the field of optics. This is because measurements of transparent objects can be affected by complex optical effects such as transmission, refraction, and multiple reflections. This study aims to investigate measurement methods for transparent objects based on polarization analysis and phase deflection techniques to improve measurement accuracy and reliability. In this article, we introduced the principle of polarization phase deflection technique firstly. Then, we set up an experimental system using polarized light sources to reduce the interference from multiple reflections. Experimental results demonstrate that the measurement method based on polarization analysis and phase deflection enhances the accuracy of measurement results. Finally, we analyzed the advantages and limitations of this method.

Slow or non- convergence is a common problem in iterative phase retrieval. This may be due to the use of few intensity patterns and the lack of intensity variation which, in turn, is highly object-dependent. In cases of partial convergence, another type of problem may occur where local phase errors appear which may arise from overfitting in the algorithmic calculations. In this study, conditions that may lead to overfitting and the appearance of local phase errors in the conventional speckle phase retrieval are investigated. It was observed that using few speckle patterns (5 images) despite sufficient number of iterations (1000 iterations) resulted in the appearance of local phase errors for the test object wave used. A phase perturbation method that uses random phase patch (with 2π depth of randomization) to remove local phase errors was demonstrated experimentally. The local phase error-removal method may be used in conjunction with other phase retrieval techniques.

This paper addresses the difficulties in achieving full-field and real-time measurement of the plasma temperature field evolution process produced by the electric explosion of metal bridge foils, both domestically and internationally. The interferometric method is adopted to measure the plasma temperature field evolution process. This method is widely used in industrial applications because it is highly efficient, high in precision, and can achieve dynamic real-time full-field measurement. Firstly, an experimental laser interferometer measurement system is established based on the Mach-Zehnder interferometric measurement system. Different physical images of the plasma at different times are obtained through experiments. The changes in the interference pattern generated in the plasma are analyzed to obtain the refractive index distribution of the plasma. A model for the refractive index and plasma temperature distribution is then established. The rationality and applicability of this model are theoretically analyzed and discussed, from which the temperature of the plasma produced after the metal bridge foil electric explosion can be deduced. The experimental results show that during the metal bridge foil electric explosion, the highest temperature in the entire flow field concentrates in the center of the plasma, reaching up to 7000K. There are also multiple temperature gradients, which remain continuously between 280 and 8000K.