This PDF file contains the front matter associated with SPIE Proceedings Volume 13280, including the Title Page, Copyright information, Table of Contents, and Conference Committee information.

Laser cleaning is widely used to remove surface contaminants and defects due to its low cost, high efficiency, and environmental protection. However, residual thermal stress caused by huge temperature gradient significantly induces thermal distortion and cracks. Due to the lack of understanding of the coupling interaction between laser and fused silica, it is still challenging to reveal the mechanism of thermal stress formation, severely restricting the further development of laser cleaning. In this article, we built a three-dimensional thermo-mechanical model to obtain the stress value and distribution of thermal stress and reveal the evolution mechanism of stress in different times and spaces. Moreover, laser cleaning experiments under different processing parameters were carried out to validate the simulated results, and theoretical simulations fit well with experimental results, which proves the effectiveness of the multi-physics model. This research provides new insights into thermal stress evolution, which can promote further development in laser cleaning technology.

Hard and brittle materials are critical components of optical systems. Due to their unique mechanical properties, these materials' surfaces are highly susceptible to damage during the grinding process. Surface damage on optical components significantly reduces their mechanical strength, laser damage resistance, and impact resistance. Therefore, it is imperative to research grinding technologies that minimize surface damage in hard and brittle optical materials. This paper begins by examining the grinding mechanisms of hard and brittle optical materials, summarizing the mechanisms of surface damage, the transition between toughness and brittleness, and their applications. Additionally, the research progress of ultrasonic vibration-assisted grinding technology is reviewed. The influence of processing parameters, such as grinding force, grinding depth, and wheel morphology, on subsurface damage is investigated. The study also explores how parameter control in the grinding process can predict surface damage and analyzes the mechanisms, advantages, and disadvantages of ultrasonic vibration-assisted grinding technology in mitigating grinding damage.

Laser Additive Manufacturing (LAM) uses laser as an energy source to enable additive manufacturing of materials which is not limited by the structure of parts and can be used for complex structures, processing, and manufacturing of difficult and thin-walled parts while realizing the manufacture of complex metals. However, some machining defects occurs in the process of LAM would affect the quality of the parts. Thus, accurate detection and feature extraction of the defect location has become an important issue. This paper proposed a hybrid polarization image fusion method for accurate defect detection. This paper is mainly through the convolutional neural network based on the Laplace pyramid and wavelet transform. The experimental results presented that the information entropy of the proposed algorithm is higher than that of the traditional method by 30.5%, the standard deviation is increased by nearly 1 time, and the intersection of the intensity image and polarization feature is realized efficiently. Furthermore, mutual fusion can greatly improve the accuracy and integrity of the target defect detection results, and the similarity reached 80%.

Fused silica is extensively utilized as a crucial optical material owing to its exceptional optical properties and thermal stability in diverse sectors such as semiconductor technology, astronomy, and military applications. However, the inherent hardness and brittleness of fused silica led to the occurrence of sub-surface defects during machining and manufacturing processes. These defects, comprising micro-cracks, scratches, and pits, remain concealed beneath the material's surface or within the post-polishing re-deposition layer, eluding conventional detection methods. Nonetheless, they exert a substantial influence on the performance of optical components, particularly in high-power laser systems. Sub-surface defects markedly diminish the laser-induced damage threshold of optical components by reducing optical transmittance, escalating scattering loss, and potentially compromising mechanical strength. This paper investigates the current theoretical frameworks and research trajectories in this domain. It delineates the application context and imperatives for fused silica optical components, elucidates the principles and ramifications of sub-surface defects, and provides a succinct overview of the contemporary research status and applicability spectrum of various damage and non-damage defect detection technologies. Furthermore, it synthesizes extant detection methodologies, delineates the merits and demerits of distinct defect detection approaches, and delineates avenues for future development and research.

In response to the application requirements for long-distance detection, identification, and ranging of a near-space UAV platform, this paper designs a common-aperture visible and near-infrared dual-band dual-mode optical system. By utilizing imaging in both the near-infrared and visible light bands, it ensures the richness of information obtained during the daytimes and takes advantage of the near-infrared's ability to penetrate fog and detect weak light for imaging, while also integrating a laser ranging function. The front end of the optical system adopts a common-aperture catadioptric structure, and the rear end uses a beam splitter to divide the optical path into a transmitted and reflected branch. The transmitted optical path is designed based on an InGaAs detector array of 1280×1024 (5μm), with a working wavelength of 0.4μm to 1.7μm. The focal length of the transmitted light path is 650mm, and the F-number is 4, which is used for detection and identification of long-distance targets. The reflected optical path is the laser reception optical path, with a working wavelength of 1.535μm, used to achieve long-distance laser ranging. Compared with parallel plate beam splitting, the use of a cube beamsplitter in this system eliminates the prerequisite for parallel incident light, thereby streamlining the optical path and contributing to the overall compactness and lightweight nature of the system. The optical system has achieved passive heat dissipation in the temperature range of minus 70 degrees Celsius to 65 degrees Celsius. The system's Modulation Transfer Function (MTF) remains impressively close to the diffraction limit across this entire temperature spectrum. The weight of the optical system is 565g, and the external dimensions are 235mm. While meeting the stringent performance requirements of long-distance laser ranging and dual-band detection, the advantages of miniaturization, lightweight, and integration technology are evident.

Shack-Hartmann wavefront sensor (SHWS) is widely applied in surface detection, astronomical observation, and ophthalmic optics. The accuracy of SHWS is heavily influenced by coupling errors caused by factors such as the light source, component position, and wavefront reconstruction algorithm. Traditional methods cannot extract information about individual errors, impeding subsequent analysis of error sources. This study proposes a SHWS model based on physical optical propagation. Compared to traditional simulation and calibration methods for SHWS, this model can intuitively analyze the influence of each error on reconstruction accuracy. Therefore, this model is expected to reduce installation difficulty, improve detection accuracy, and provide an essential reference for accurately measuring optical systems.

High-performance optical surfaces are crucial in advanced optics as they ensure the performance and longevity of essential devices. Achieving high-performance optical surfaces involves strict contour control requirements and demanding machining accuracy standards. The capability to manufacture these surfaces depends on advancements in manufacturing processes and machine tool equipment for difficult-to-machine optical materials. In the manufacturing process of high-performance optical surfaces, polishing technology and machine tools play a central role. This includes critical polishing technologies and related machine tools such as CCOS small grinding head polishing, bonnet polishing, and magnetorheological finishing. These technologies have unique polishing mechanisms, processing characteristics, and deep academic and application backgrounds. The current status and progress of research by optical manufacturers and scholars and the associated problems and risks of different polishing techniques and equipment in processing high-performance optical mirrors are discussed. To meet the extreme manufacturing accuracy requirements of optical components in the future, technical challenges and development directions are pointed out. Developing new polishing machine tools and equipment is necessary to meet the ever-increasing precision requirements of optical surfaces. This will promote the development of high-performance optical surface manufacturing technology to achieve extreme precision, higher efficiency, and a more comprehensive range of applications.

As the core component of the optical system, the design of the main mirror not only directly determines the image quality of the camera but also influences the mechanical balance, thermal stability, and the economic efficiency and difficulty of the overall design and manufacture of the space camera. Given the core position of the main mirror in the performance of the camera, achieving its dual optimization design of high precision and lightweight has become the key technical bottleneck and breakthrough point for promoting the innovation of space camera technology and ensuring the efficient and stable operation of the camera in the extreme space environment.

In this paper, the SiC material with high specific stiffness and excellent thermal conductivity is selected as the mirror body material, and the flat back open structure and triangular lightweight holes are adopted. The weight is successfully reduced to 6.7 kg, and the lightweight ratio exceeds 70%, which realizes the structural strengthening and thermal stability improvement of the Φ480mm aperture primary mirror. Additionally, to address the challenge of imaging stability for large-aperture and long-focal-length cameras, this paper designs the support structure of the carbon fiber load-bearing tower for the primary and secondary mirrors and adjusts the support structure based on the topological optimization results to ensure stable connection and support between the primary and secondary mirrors and effectively resist the influence of space environment changes on imaging quality. To verify the scientificity and practicability of the design scheme, finite element simulation analysis is conducted to verify the analysis and optimization. The static analysis results indicate that the total rigid body displacement of the mirror assembly meets the requirements. The modal analysis verifies that the first-order natural frequency of the entire structure of the camera's primary and secondary mirrors is 142.76 Hz, which satisfies the stiffness requirements. The sinusoidal and random vibration analysis shows that the maximum stress generated by each component is small. The above analysis verifies that the mirror and its supporting structure meet the stiffness and strength requirements and possess good dynamic performance. The design scheme can fulfill the strict optical design requirements of space astronomical cameras and lays a solid foundation for enhancing the overall performance of space cameras.

ZnS crystal is a multispectral infrared optical material with excellent optical and mechanical properties. Due to its large brittle properties, low hardness, and poor machining performance, Single Point Diamond Ultra Precision Turning Technology (SPDT) is the effective fabrication method for ZnS at present. However, the machining accuracy of the SPDT method is limited by the principle of "error copying", which cannot meet the application of high precision applications. Moreover, the traditional polishing method cannot achieve the high efficiency of surface shape accuracy and surface quality improvement of aspherical elements. In order to meet the demands of high precision surface shape and high surface quality of ZnS aspherical optical components, a new combined polishing technology which consists of Magnetorheological Finishing (MRF) and Small Tool Polishing (STP) technology is presented and researched in this paper. Firstly, the Magnetorheological Finishing method is used to achieve the deterministic convergence of surface figure error rapidly. The quantified relationship between process parameters and process defects is established through a series of experiments. Through the optimization of MRF polishing fluid and processing parameters, the surface quality is controlled from sharp deterioration while removing the cutting knife lines. Then STP method is used to improve the surface quality while maintaining the surface figure accuracy. This combined polishing technology is conducted through validation experiments on the ZnS experimental sample. The surface figure error is reduced by 3 times after polishing and the surface roughness is below Ra 1nm. This result validates the effectiveness of the combined polishing technology proposed in the paper.

Optically variable devices (OVD) are esteemed security elements renowned for their capacity to produce structural color effects reliant on multiple angle-dependent information channels. In this paper, based on the patterning of single-point diamond ultrasonic oblique elliptical vibration texturing, a novel strategy for micro/nano grating structure encoding for multi-layer high-definition structural color images is proposed and demonstrated. The innovation of this paper lies in the design of a rotating stable bracket equipped with ultrasonic vibration tool, allowing for the flexible adjustment of the tool angle to generate an oblique elliptical vibration texture. Firstly, this paper establishes a mathematical model of grating spatial diffraction, extending it from a two-dimensional plane to three-dimensional space, and determines the variation trend of grating diffraction efficiency in different directions within the spatial observation domain. Secondly, the relationship between grating and structural color is established via the micro-optical theoretical model, so as to determine the mapping between pixel color information and cutting velocity. Finally, single-point diamond ultrasonic oblique elliptical vibration texturing is used to achieve ultra-fast pixel-level drawing of sub-micron gratings with controllable spacing. Simultaneously, the tool deflects at set angles to machine grating structures for different images. This method flexibly controls the convergence direction of diffracted light, thereby realizing three-layer image encoding. The research results show that OVD exhibits the ability to selectively display target image information from various observation angles, indicating that the three-layer image encoding is decoupled.

Industrial robot plays an irreplaceable role in various industries of modern manufacturing, such as automotive, logistics, heavy industry, and electronics. Industrial six-axis robot, as a multi-joint serial mechanism, has relatively low absolute positioning accuracy due to errors in the manufacturing and assembly process, which cannot meet the increasingly precise operation scenarios. Field-operation calibration is necessary to improve their absolute positioning accuracy. Traditional calibration methods mainly rely on high-precision external measurement equipment such as laser tracker, but such equipment is expensive, and considering the transportation time, the timeliness of field-operation calibration cannot be guaranteed. This paper proposes a method for industrial robot calibration based on 3D vision. The robot carries a standard ball and moves to multiple positions within the field of view of the 3D vision sensor, which can complete the robot calibration. The experimental results show that: after calibration, the absolute positioning error of the robot is reduced by 65%, when the calibration results are applied to vision-guided grasping, the vision positioning error is reduced by 30%, and the robot grasping error is reduced by 33%. Moreover, this method does not require the assistance of additional high-precision measurement equipment, and it has low cost and good timeliness.

The PSD2 index of 3mm ultrathin large aperture optical components is difficult to converge effectively, which is influenced by various factors. In order to solve the problem, the measurement results of the PSD2 index were analyzed in two parts. One part was the results of the PSD2 index after removing the defocus and astigmatism, which we used to evaluate the impact of intermediate frequency errors. The other part was the surface shape PV value of the measurement area, which we used to evaluate the impact of low frequency errors. In the double-side polishing stage, the oscillating smooth polishing technology was used to smooth intermediate frequency errors of the optical surface, which eliminated the fine ripples in the PSD2 processing results. The surface shape local correction technology was used to improve the surface shape PV value of the measurement area. Through the synchronous control of the intermediate frequency and low frequency errors, the PSD2 index control for the whole surface of the optical components was realized. The RMS value of the the PSD2 index was converged from 1.38nm to 0.70nm on average.

There is an urgent demand of novel X-ray optics for high heat load and radiation damage resistance for the new light source development. The compound refractive lens (CRL) is a good choice for the photon beam manipulation. Diamond, SiC and sapphire have been proved to be the preferred materials for CRL. However, on account of these materials are hard, brittle and difficult to process, conventional preparation prevents highly precise removal of materials. Meanwhile, CRL achieves X-ray focusing by stacking multiple lens units, which requires efficient and precise processing method to ensure that the error of each single lens is within an acceptable range. This paper uses scanning confocal laser microscopy and synchrotron X-ray computed tomography (CT) techniques to detect the manufacturing errors of bi-paraboloidal 2D focusing X-ray lenses of curvature radius R=1000 μm and aperture D=2000 μm produced via femtosecond laser ablation. Point cloud processing method is introduced to accurately characterize the relative position of two paraboloids deviation. The results showed that the local micro-roughness of lens surface is about 400 nm S_q. Relative transverse offsets of the front and back surfaces can be controlled within 35 μm and the axis deflection angle of the front and back paraboloid is between 20 and 40 mrad. Using the aforementioned methods, the manufacturing errors of bi-concave lenses can be effectively obtained, providing feedback for the optimization and improvement of process parameters.

As the third-generation wide band gap semiconductor material, single crystal silicon carbide has high electron saturation mobility and excellent thermal properties. It has broad application prospects in the manufacture of high temperature and radiation resistant high frequency and high-power devices. Magnetorheological polishing of silicon carbide wafers has the characteristics of high efficiency and non-destructive processing, but there is a lack of research on magnetorheological polishing of Si and C surfaces at this stage. Therefore, this paper studies the following aspects. Firstly, through the removal function experiment of multi-parameter comparison, the difference between the residence time of magnetorheological polishing and the removal effect of SiC Si and C surfaces is analyzed, and the efficiency evolution law of magnetorheological polishing of different crystal surfaces is obtained. The influence of different immersion depth of polishing ribbon on the removal efficiency of different crystal faces was explored, and the relationship between polishing depth and material removal rate under different crystal faces was obtained. The results show that with the increase of residence time, the removal efficiency of Si and C surfaces increases, and the growth rate of Si surface is much larger than that of C surface. With the increase of immersion depth, the growth rate of material removal efficiency of C surface is more sensitive than that of Si surface. Therefore, this study explores the technical feasibility of magnetorheological polishing of SiC, and provides a new idea for high-efficiency and high-precision polishing of SiC.

Dark-field imaging systems demonstrate significant advantages in the field of unpatterned wafer front-end defect inspection attributed to their high sensitivity, low cost, and high throughput. However, as optical systems with large numerical apertures (NA) are applied and inspection wavelengths gradually extend into the ultraviolet range, optical systems become extremely sensitive to defocusing. Surface variations on the wafer in the order of micrometers can cause complete defocusing in optical systems, leading to false positives and false negatives. To address this issue, this paper introduces a depth of field (DOF) extension method for dark-field inspection systems based on digital holography. Digital refocusing techniques is used to calculate the image stack at different focal depths based on the scattered light wave-front reconstructed from the hologram, and a focus measurement function evaluates each image to determine the optimal focal position. Finally, images near the optimal focal point are fused to create an all-in-focus image containing defect information on the wafer surface. The comparison between the processed results with the well-focused portions of the real captured images shows that the method accurately restores the distribution of defects on the wafer surface. The post-processing method extends the DOF of the optical system without compromising scanning efficiency, providing a solution to the defocusing issue in dark-field inspection systems for wafers.

Fused quartz material demonstrates strong ultraviolet light transmission and resistance to laser damage, making it the primary choice for selecting large-diameter optical components in high-power laser systems. The challenge now lies in achieving low damages and high resistance to laser damage. A significant number of large-scale (with characteristic depths ranging from 10μm to 100μm) Sub Surface Damages (SSD) are generated in grinding stage, requiring substantial material removal during the subsequent polishing stage to ensure the damage resistance performance of the components. Therefore, it is crucial to study damage control in grinding stage for achieving optimal subsurface quality in optical components. This paper focuses on the processing state of fused quartz components under various grinding processes. Initially, a comparative experiment is conducted using loose abrasive and bonded abrasive with the same grain size (6μm), followed by an examination of three different grain sizes (6μm, 9μm, 20μm) of bonded abrasive grinding processes. After grinding, all processed samples are appropriately etched to reveal subsurface damages. The damage distribution and morphological information of the experimental samples are observed using optical microscopy and scanning electron microscopy. The value of surface roughness (Rz) of the fused quartz samples is measured using white light interferometry, and the corresponding SSD is calculated using the empirical formula of Kun Xiao. The findings indicate that the bonded abrasive processed samples exhibit higher removal efficiency and smaller SSD compared to the loose abrasive samples.

With the continuous improvement of optical system imaging quality requirements in astronomy, aerospace engineering, laser technology and other fields, in order to capture lighter objects and improve image resolution, the size of the mirror is getting larger and larger. Therefore, to meet various usage scenarios and operational constraints, the lightweight design of large mirrors has become an important research focus. In this paper, the lightweight structure design of the primary mirror of the 2.0m large aperture mirror system is studied in terms of the lightweight form of the mirror back and the shape of the lightweight hole. With the increase in the size of the primary mirror, the traditional material will no longer be able to ensure a good surface shape, so high-strength, low-density silicon carbide (SiC) is used as the main mirror body material. To achieve a high lightweight rate and maintain high internal stiffness, the simulation examined triangular, fan-shaped, and rectangular lightweight holes on the back of the primary mirror to determine the most stable form. In addition, this paper also compares the full-open and semi-closed lightweight forms. Finally, the semi-closed triangular lightweight back structure was used, and the displacement deformation and mirror profile accuracy of the 2m large aperture mirror under X, Y and Z gravity conditions were checked by the finite element analysis software Hypermesh and Patran. The final mass of the 2m mirror main mirror structure is reduced by 78%, and the surface profile (RMS) achieves 𝜆/40.

The application of diffractive optical elements in optical systems can effectively correct chromatic aberration and improve imaging quality. The processing accuracy and diffraction efficiency of diffractive optical elements can determine the application range of diffractive optical elements. The injection molding process can greatly reduce the manufacturing cost of diffractive optical elements. The surface accuracy of injection molded diffractive optical elements is largely guaranteed by the surface accuracy of the mold core. In order to improve the diffraction efficiency of the shaped diffractive optical element, higher requirements are placed on the machining accuracy of the diffractive optical core. Therefore, this paper studies the ultra-precision turning process of diffractive optical element die core. Firstly, the relationship between the processing parameters and the manufacturing error of the diffractive optical element core is constructed. Then, based on the relationship between the processing parameters and the manufacturing error, the mathematical relationship model between the processing parameters and the diffraction efficiency is constructed. A method for optimizing the height error, period width error and surface roughness of the microstructure during the processing of diffractive optical cores is proposed. Based on this method, an ultra-precision cutting experiment was carried out on the nickel-phosphorus surface with a diffraction grating die core with an aperture of 15 mm. The machining results of the period width error are 6.1μm, the microstructure height error is 0.0454μm, the surface roughness of Ra is 0.816nm and root mean square (RMS) is 1.06nm. Under the experimental results of surface quality, the polychromatic integral diffraction efficiency of the diffractive optical element can reach 98.7 % in the range of 0.45-1.2μm. The results show that the optimization method applied in this paper can ensure the key performance indexes of the diffractive optical element, the machining accuracy and diffraction efficiency of the shaped diffractive optical element can be improved. It lays the foundation for the ultra-precision cutting of the diffractive optical element and the diffractive optical element. Besides, this research can expand the application range of the diffractive optical element.

Compared to traditional spherical and aspherical surfaces, freeform surfaces offer extensive design freedom, which can be fully utilized to correct and balance asymmetric aberrations, achieving system parameters, structures, and functions that are difficult to realize with conventional optical systems. This has made freeform surfaces a research hotspot in the fields of optical detection and imaging. Currently, freeform surface off-axis reflective systems are widely used in space detection and extreme ultraviolet lithography objective lenses due to their advantages of no obstruction, no ghost images, and a large field of view. This paper focuses on a four-mirror off-axis optical system, studying the alignment methods for such systems. By deeply investigating the relationship between aberration characteristics and misalignment, the aim is to address issues of blind alignment and long assembly cycles associated with traditional methods, thereby providing more precise technical support for optical system assembly.

The nonlocal effect is studied for a functionally graded (FG) nanobeam, which is widely used in the Nanoelectromechanical system. First, the higher-order deformation mode is introduced in terms of the generalized displacements defined for the cross section. Generalized stresses and strains are accordingly defined and uncoupled constitutive relations are derived by combining the nonlocal elasticity theory. Next, according to the principle of virtual work, an uncoupled beam theory is established for a FG nanobeam, including governing equations and boundary conditions. The current work shows that, due to the decoupling of bending, tension and higher-order bending, the nonlocal effect can be attributed to the superimposition of equivalent initial generalized stresses. Typical FG nanobeam problems are analytically solved. It is found that the nonlocal effect on the deflection of FG nanobeam is case dependent for different boundary constraints.

For airborne optoelectronic platform with two axes and four frames, the dynamic model of vibration reduction system is established. Simulation analysis and experimental test for vibration reduction system are made under the condition of stiffness perturbation and barycenter perturbation respectively. Simulation results show that linear vibration accounts for angular disturbance when stiffness perturbation or barycenter perturbation exists. Angular disturbance error is 25μrad and 34.28μrad when barycenter perturbation is 1mm and stiffness perturbation is 1% respectively. Vibration experimental test results show that coupling exists in combination of two kinds of damping system. Angular disturbance coupling of damping system becomes less when stiffness perturbation and barycenter perturbation are reduced. The method provides a new train of thoughts for making a reasonable configuration on stabilized platform damping system.

The primary mirror system is the key component of the high-precision optical system, and the surface accuracy of the primary mirror determines the imaging quality of the whole system. When the surface accuracy of the primary mirror decreases, the optical performance of the whole optical system will be seriously affected. At this time, the primary mirror of the primary mirror assembly needs to be disassembled, and the secondary assembly of the primary mirror assembly is carried out until the assembly index is met.

In this paper, the research object is a 98 mm aperture glass-ceramic primary mirror component, which is composed of a glass-ceramic primary mirror and a primary mirror backplate, and the bonding method is central axis epoxy 2216 adhesive. When the surface shape of the primary mirror changes and exceeds the expected result, the primary mirror and the back plate of the primary mirror need to be removed, and the primary mirror needs to be reassembled. Aim at that bonding mode of the primary mirror component, the primary mirror component need to be placed in a hot oven, and the epoxy 2216 adhesive is inactivated by high temperature baking, so that the micro crystalline glass is separate from the back plate of the primary mirror. In the actual operation process, the heating rate of the thermal oven is too fast, and a higher temperature gradient appears on the surface of the primary mirror. Because of the appearance of the higher temperature gradient, the stress distribution of the primary mirror in the glass-ceramic exceeds its tensile strength, resulting in cracks on the surface of the primary mirror in the glass-ceramic. In this paper, combined with the material properties of glass-ceramics, the causes of cracks are analyzed, and according to the analysis results, a safe disassembly process is formulated for the future disassembly of glass-ceramics.

In superluminescent diode (SLD), the height difference between the two shoulders of the kovar bracket (referred to as the shoulder difference) has a significant impact on the rate of change of SLD full temperature power (ΔP). To reduce the rate of change of SLD full temperature power, this paper verifies the influence of four sets of double shoulder differences at different heights on SLD full temperature power, and establishes a quantitative relationship between double shoulder differences and SLD full temperature power stability. The experimental results show that the shoulder difference is less than 10um, the mean Δ P is 1.86%, and the standard deviation is 0.008; the shoulder deviation is between 10um and 20um, with a mean Δ P of 2.88% and a standard deviation of 0.014. The shoulder deviation is between 20um and 40um, with a mean Δ P of 3.87% and a standard deviation of 0.016; the shoulder difference is greater than 40um, with a mean Δ P of 5.9% and a standard deviation of 0.040.

A new method to study the influence of pentaprism micro motion on the steering angle of the outgoing ray has been proposed in this paper. Comparing with the traditional research methods, the new method ensures the absolute accuracy of the calculation results, and at the same time it greatly reduces the calculation amount and complexity. Both the derivation process and the calculation formulas are extremely simple. The calculation results of the new method are analyzed by MATLAB. The influence rule of pentaprism micro motion is summarized. The calculation formulas of the angle error of light is given. And relevant experiments are designed to carry out a large number of tests on the pentaprism. The results show that: The formulas that obtained by this method which show the steering angle of outgoing ray and the error of that ray are in agreement with the experimental results within a reasonable range. So the results further verify the correctness of the new method and the applications to the relevant engineering.

In this paper, a concave holographic grating aberration optimization method is designed, which performs well in the aberration optimization of multi-channel narrow-band gratings. Taking the grating in the the project of CAFE (the Census of warm-hot intergalactic medium, Accretion, and Feedback Explorer) proposed by the Purple Mountain Observatory, Chinese Academy of Sciences, as the optimization target, this paper compares the method proposed with the traditional aberration function method and the spot diagram method commonly used currently in terms of the evaluation perspectives such as the line density deviation, the focusing curve offset, and the exit slit luminous flux, etc., and the optimization time is one thirtieth and one sixtieth of the two methods, respectively.

Research on reinforcement learning multi degree of freedom control system for shape testing of space camera mirror. Based on the optimization design of the perception control execution closed-loop intelligent testing system, reinforcement learning pose joint control training and testing are carried out based on the position information of the laser tracker and the misalignment information data of the laser interferometer. Complete automated testing experiments and validation. Improve the accuracy and efficiency of the testing process, reduce labor costs, and enhance the automation level of space camera installation and inspection.

R-C optical systems commonly used in long focal length imaging, long-distance detection fields such as aerospace and space optical communication. In this paper, the R-C optical system consists of two reflective mirrors and four correction lenses. The primary mirror adopts three sets of flexible structures for back support, which can provide a reasonable access to reduce the influence of the mirror's self-weight and thermal distortion on the mirror surface. For the high accuracy assembly, the simulation has been conducted firstly by sensitivity matrix method to figure out the sensitive components and corresponding geometrical parameters about the focal length, wavefront aberration, and energy concentration and an assembling method is proposed. Experiment is carried out to demonstrate the feasibility of the proposed calibration method, for the wavefront aberration with RMS value of center of view is 0.17λ (λ=0.6328nm), and the diameter of spot dispersion about center field of view is 12.35μm, the diameter of spot dispersion in full field of view better than 18μm can be achieved.

Dark-field inspection systems have high detection sensitivity and high resolution, and are widely used in the field of bare wafer inspection. By adding polarization elements to the dark-field detection system, the optical scattering on bare wafer surface can be used to detect defects, and the detection accuracy can be improved. The scattered light not only depends on the polarization state of the incident light, but is also affected by the physical properties of the defects on the wafer surface and the complexity of the scattering process. When there are defects on the wafer surface, such as dirt, particles, scratches, the scattered light will change. This change can be detected by a dark-field detection system to identify the defect. However, how to choose the appropriate polarized light so that the detected signal intensity is higher is the main concern in polarization modulation techniques. In this paper, several common defect types in wafer defect detection are simulated. Linear polarized light is used as the illumination source of wafer defect detection system. By changing the polarization state and incidence angle of the illumination source, a simulation model of wafer defect detection based on polarization modulation is established. The simulation results show that by adjusting the polarization state and incidence angle of the illumination source, the intensity detection signal of certain types of defects can be improved, so as to guide the polarization illumination and detection involved in wafer defect detection system.

Cryogenic optical technology aimed at reducing background radiation is the main way to improve the infrared detection capability of space cameras. This paper elaborates on the method of assembly and testing for a cryogenic optics infrared camera with full optical path cooling from the perspective of engineering applications, providing a certain reference for the development of other cryogenic optical cameras. An elastic support framing method for ZnSe lens is proposed, by matching the stiffness of the elastic support structure, and using the rod tooling to accurately and quantitatively compress the spring, the lens meets the requirements of the mechanical environment. The RMS change of the surface accuracy from room temperature to 90K is less than 0.02λ, and the effectiveness of the framing method is verified by experiments. The assembly method of thermal conductive components was optimized. By comparing the working temperature and contact heat transfer coefficient of different interface thermal conductive fillers, indium foil was selected as the optimal interface material. Through simulation analysis of interface contact pressure, the optimal mechanical connection method was formulated. The installation method of multilayer insulation are improved. By staggered lapping, reserving low temperature shrinkage allowance, increasing the multi-layer interval, the thermal insulation effect of MLI has been significantly improved. By using the method of presetting the focal plane at room temperature and conducting over focusing tests under low temperature conditions, the optimal focal plane position is determined to ensure that the camera MTF and energy concentration meet the requirements.

X-ray mirrors are widely utilized in light source devices like synchrotron radiation (SR) and free electron laser (FEL) light source. The Root-Mean-Square (RMS) value of surface figure accuracy required for these mirrors is typically sub-micro radian or sub-nanometer, and their aperture can be hundreds of millimeters or even meters. To achieve this accuracy, deterministic figuring is required and surface figure error is the premise. Interferometric stitching test is commonly utilized. Interferometric test obtains the surface figure of the tested X-ray mirrors mounted on a mounting support. Due to the low stiffness of the X-ray caused by the large ratio of length/width and length/height. The mechanical stress induced by the mounting supports may have a non-negligible influence on the surface figure of the mirror surface. Moreover, this can result in the poor reproductivity when testing the mirror under different mounting situations and with different mounting craft. What kind of aberration will be introduced by the X-ray under different mounting supports and whether it can be neglected is still an issue. To this end, the reproductivity of a typical silicon X-ray mirror with size of 500 mm × 50 mm × 50 mm were tested on different typical supports with a 24” zygo interferometer. Comparison of the introduced aberration type and aberration amplitude were conducted to reveal the deformation of the X-ray mirror on different typical supports. The results of this paper may attract the community that fabricates, tests, or uses X-ray mirror to pay a special attention to the mounting supports when testing the surface figure the X-ray mirrors.

The demand for spatial infrared remote sensors with high spatial resolution and wide imaging swatch becomes more and more urgent. Optical system is an important constraint on the performance of spatial infrared remote sensors. In this paper, a novel off-axis catadioptric optical system configuration with intermediate image is proposed. The imaging principle and the initial configuration solution method are analyzed. And an off-axis catadioptric freeform optical system is designed with the spectrum of 7.8-10.2μm, the aperture of 435 mm, the focal length of 1038 mm, and the field of view (FOV) of 9×1.1°. The modulation transfer function (MTF) value is better than 0.316@25lp/mm. The maximum relative distortion is -0.27%. And this optical system has good image-side telecentricity and image illumination consistency. The results show that the spatial infrared off-axis catadioptric freeform optical system has good imaging quality and engineering feasibility.

Graphite balls are essential in various industries, including casting, lubricating materials, refractory materials, batteries, and more. With expanding industrial applications, detecting surface defects on graphite balls has become crucial to ensure product quality and performance. Manual detection methods are often inefficient and error-prone, failing to meet modern industrial demands. This research focuses on using the YOLOv5 model for fast and accurate detection of surface defects on graphite balls, enhancing detection efficiency and accuracy. Traditional methods struggle with complex backgrounds, noise interference, and diverse defect morphologies. The study employs the YOLOv5 model with CSPDarknet53 and compares it with SE attention mechanisms, adaptive convolution (SAConv), and BiFormer modules for small target detection. Attention mechanisms improve focus on defect areas, while adaptive convolution enhances feature extraction. The BiFormer module improves accuracy for smaller defects.The final model detects four types of defects: tool marks, sintering marks, scratches, bumps, and risers, providing valuable data for industrial production. This research offers a high-precision solution for graphite ball surface defect detection and serves as a reference for applying neural network models in industrial defect detection.

The relationship between the diffraction distribution of random metal mesh mesh and the linewidth of the mesh was analyzed by theoretical calculation and FDTD Solutions software simulation. A random-structure metal mesh electromagnetic shielding film with a line width of 5 μm was prepared on a large-aperture germanium optical window by mask vacuum lithography and electron beam evaporation coating technology, and then the infrared dual-band anti-reflection coating and DLC protective film were coated by electron beam evaporation and PECVD on the germanium window, respectively. Furthermore, the transmittance in the infrared band and electromagnetic shielding effectiveness in the microwave band of the window were characterized. The results show that the windows coated with random-structure metal meshs, anti-reflection coatings and DLC films have excellent electromagnetic shielding effectiveness in the frequency range of 1GHz~18GHz, and have high transmittance in the 3.5μm~4.5μm and 7.5μm~9.5μm bands.

Precision glass molding (PGM) represents a highly effective method for producing infrared chalcogenide (ChG) glass aspherical microlens arrays (AMLA). However, ChG glass, primarily composed of Ge, As, and Te, exhibits lower chemical stability compared to typical silicate glass. When subjected to high temperatures and pressures during molding with a nickel-phosphorus (Ni-P) mold, ChG glass tends to react with the Ni element, resulting in the formation of a shielding layer on the lens surface. This phenomenon significantly impacts the infrared transmittance of the ChG glass lens, rendering Ni-P mold unsuitable for direct apply in ChG glass PGM. Ni-P mold can be effectively utilized for the high-temperature molding of silicate glass, serving as the intermediate mold for subsequent low-temperature molding of ChG glass. This dual-step approach has been validated by detailed analysis of the profiles of the final ChG glass AMLA, thereby providing a viable method for the fabrication of ChG glass AMLA through PGM.

In the field of space optics, due to the wide application of large-aperture long-focal length optical system, aspheric mirror as an important component, its aperture is getting larger and larger, in order to save the emission cost, the lightweight degree of the optical element is also increased, due to the influence of gravity field, the mirror will be deformed, so it is of great significance to eliminate the gravity error through the ground test method, and accurately evaluate the on-orbit quality of the optical element.

Based on the orthogonality of different aberrations, a method combining the rotation and flip test and finite element simulation is proposed to measure the zero gravitational wavefront error of the mirror. The astigmatism is extracted by the rotation test of the mirror, and the assembly error and the support error are separated by the flip test of the mirror assembly, and the on-orbit quality of the mirror is obtained. Compare with the mirror shape of finite element analysis to form a closed loop. The φ1100mm high-lightweight mirror was tested by this method, and its 0 gravity wavefront was 0.014λ (@632.8nm), which was verified in orbit.

Owing to the powerful capability to manipulate light of the metasurface, here, we propose an ultra-compact differential confocal sensor based on two dielectric metasurface layers, in which the conventional focusing lens and beam splitter are replaced by the dielectric metasurfaces. We introduce the design of the dielectric metasurfaces based on truncated waveguide-type silicon nitride meta-atoms at the wavelength of 633 nm. The focusing performance of each metasurface was studied by the finite difference time domain method. Subsequently, the performance of the differential confocal system was simulated according to the ray tracing method. Metasurface-based optical sensors are expected to serve as the foundational elements of low-cost, miniaturized, and lightweight optical sensors in the future.

This paper addresses the issues of high qualification rates and consistency required in the engineering production process of Fiber Optic Gyroscope, and introduces the optical path scheme of Fiber Optic Gyroscope in conjunction with the characteristics of optical path transmission. Test method designs for the roles of involved optical devices in the gyroscope's optical path are presented, along with theoretical analysis calculations from aspects such as optoelectronic device tail fiber matching and loss matching. After applying optical device matching technology to the engineering of Fiber Optic Gyroscope, it effectively solved the consistency problem of the output signal assembly of the gyroscope's optical path, reduced the dispersion of the zero bias stability index at room temperature for engineering products, increased the proportion of products with an accuracy of 0.03°/h-0.05°/h from 52% to 87%, and raised the qualification rate for one-time testing at room temperature from 78% to 96%.

With the rapid development of railway transportation in China, Inspection and maintenance of railways are becoming more important. It is of great practical significance to realize the measurement of track geometric parameters efficiently and quickly for guiding fine tuning and railway maintenance. Aiming at the problems of low efficiency and high labor cost in traditional orbit detection, a fiber optic gyro inertial navigation system is proposed to measure the geometric parameters of orbit,so as to realize the efficient, continuous and accurate measurement of track parameters. Aiming at the application scene of railway track measurement, the fiber optic gyro inertial navigation system is installed on the railway track detection vehicle. In order to reduce the influence of accumulated error of inertial navigation system, the combination of inertial navigation system and odometer is adopted. Then the geometric parameters such as track direction and longitudinal of the track are calculated. In this paper, the updating algorithm of orbit attitude position is deduced, the calibration method of installation error in orbit detection scene is given, and the actual orbit test is carried out.

Based on the track parameters measured by the total station, according to the position output by the system, the track direction and longitudinal value of 10m chord length is calculated and compared with the reference value. The track test experiment shows that, Excluding the measurement error of the total station itself, the error accuracy of the track parameters calculated by the system is less than lmm and the repeatability is less than 0.5 mm. with the traditional measurement method, this method effectively improves the relative measurement efficiency of the railway and lays the foundation for the precise inspection of the railway.

Gyroscope is a sensor that measures angular velocity, which is widely used in precision guidance, deep-sea operations, unmanned driving, etc. Currently, the gyroscope is moving towards the trend of compactness, high accuracy, high reliability and low cost, and the resonance integrated optical gyroscope is expected to be a preferred choice for the next generation of optical gyroscopes. In this paper, the finite element method is used for modeling and numerical simulation of silicon-based optical waveguide micro-ring resonator, a sensitive unit of resonant integrated optical gyroscope, in two-dimensional and three-dimensional, to research the effect of structural parameters of the resonator on its performance. Simulation results show that the free spectral width of the Si-based optical waveguide micro-ring decreases with increasing radius. The resonant depth of the micro-ring increases with the coupling spacing in a certain range, but it decreases with the coupling spacing beyond the critical coupling. In addition, the quality factor of the micro-ring resonator increases with the increase of radius. The research in this paper lays the foundation for performance optimization of the resonator.

The large-aperture optical elements are widely applied in various fields, but surface defects of the optical elements will reduce the system performance. Defect detection is one of the main interests of optical measurement research. To achieve defect detection of large-aperture elements, the defect images need to be stitched. This paper proposes a defect image stitching method for large-aperture optical elements based on the adaptive dimensionality reduction registration (ADRR) algorithm and the gradual weighted fusion (GWF) algorithm. The ADRR algorithm adaptively reduces the dimensionality of feature point descriptors extracted by the popular scale-invariant feature transform (SIFT) algorithm, and the low-dimensional descriptors are used to match feature points. The GWF algorithm constructs gradual weight matrices based on the column coordinates of overlapping areas, achieving seamless stitching of defect images. The experimental results show that the ADRR algorithm has a higher effective matching rate and shorter matching time than the SIFT algorithm. The GWF algorithm effectively reduces the interference caused by uneven background brightness. Therefore, the stitching method has good robustness and practicability.

Large array remote sensing camera detectors have a large number of blind pixels, which is difficult to correct in real-time in orbit. It is difficult to meet the requirements of pixel-level image processing algorithms such as image feature extraction, registration and fusion. In this paper, based on the integrating sphere radiation calibration system, a method suitable for real-time blind pixel correction of large array space remote sensing cameras in orbit is proposed to solve the problems such as a large number of blind pixels, limited in orbit hardware resources, and high difficulty in real-time correction of high frame rate blind pixels. This method firstly performs blind pixel calibration on the ground. In orbit, a "3*3 sliding window" is used to calculate the address information of each pixel in real-time, as well as the distribution of blind pixels around the pixel and the replacement value of detector response. Determine the output original value or substitute value based on the segmentation of blind pixels around the pixel, and complete blind pixel correction. This method can take into account the situation where the blind pixels are located at the edge of the detector. This method has high reliability, less consumption of hardware resources in orbit. This method has no need for image download, and can match high frame rate image output. It has important reference significance for improving the temporal and spatial resolution of the large array space remote sensing cameras and improving the signal-to-noise ratio of the output images.

The annular beam generated by an axicon-pair with laser beams is an important illumination method for optical inspection microscopies and Deep-Ultraviolet lithography off-axis illumination modes due to its variable-diameter flexibility, economic efficiency and accessibility. The annular ring beam quality is determined by the quality of the optical components, which depends on the manufacturing level. However, there is a lack of a comprehensive evaluation for such ring beams, as only the ring shape feature has been briefly mentioned with coherence factors in the pupil evaluation of lithography illumination systems. In this work, we established a comprehensive evaluation system for annular beams based on the far-field divergence angles, geometric characteristics and uniformity of the light intensity distribution. We aim to propose a comprehensive evaluation system for the annular beam quality which enables the analysis and improvement of ring beams quality to better meet various application requirements.

With the advancement of ultra-precision machining, lenses with three-dimensional microstructures have gradually emerged and are widely used in near-eye display devices, infrared imaging, solar concentrators, and other application fields. However, various parameters of the three-dimensional microstructure arrays, such as the corner radius of the microstructure and defects on the working surface, can all impact imaging quality to varying degrees. Therefore, systematically studying the effects of these parameters on imaging quality is of significant importance for optimizing microstructure design and enhancing the performance of optical imaging systems. Simulation results show that the effects of each parameter on imaging quality vary. Defects on the working surface lead to noise in the imaging, reducing image contrast. Rounded corner of microprism lead to trailing artifacts when imaging high-contrast objects. This study reveals the specific impact of each microstructure parameter on imaging quality through systematic simulation experiments and theoretical analysis, providing a theoretical foundation and experimental basis for optimizing the design of prism microstructure arrays. This will aid in the development of higher-performance microstructured optical devices.

Transparent objects are extensively utilized across various aspects, yet their non-destructive optical measurement remains challenging. In-line lensless digital holography has emerged as an efficient and precise technique for detecting transparent objects, with the advantages of simpler device requirements and more effective utilization of the detector limited spacebandwidth product. However, the presence of twin-image significantly degrades the quality of the reconstructed images. Conventional approaches to mitigating twin-image require intricate hardware configurations or time-consuming algorithms. In this paper, we proposed a new network called Attention mechanism in Convolutional neural Network (ACNet), which provides a fast and efficient deep learning solution for twin image suppression. The proposed approach utilized numerically generated datasets for training and a convolutional neural network (CNN) was employed with an attention mechanism to perform twin image removal. Simulation results demonstrate that this method effectively eliminates twin image interference in phase recovery, thereby enhances the reconstruction quality of in-line digital holography. The present work has great potentials for wider applications in digital holography.

During the process of structured light 3D reconstruction, the resolution of images plays a crucial role in the final reconstruction outcome. In practical terms, there are primarily two methods to enhance image resolution. Firstly, improving the performance of the camera can directly provide higher-resolution images, albeit at a higher cost. Secondly, employing deep learning methods for preprocessing acquired images before using 3D reconstruction algorithms offers another viable approach. In handling image processing practically, to address issues related to hardware performance due to excessively high actual resolutions, a novel classification method is employed for distinguishing and categorizing effective regions within the images. Following the classification and identification of these effective regions, super-resolution processing is applied specifically to these areas. This approach reduces the time required for super-resolution processing and mitigates the hardware demands of deep learning.

In laser triangulation measurement, high reflectivity and complex exposure environments can cause defects such as highlights, artifacts, and noise in the extracted laser stripes, affecting the accuracy of stripe center extraction. To address this problem, a U-net network structure integrated with additive attention gates is proposed. This structure uses contextual semantics to train the model to predict the weights of effective regions of the stripes, implicitly learning to suppress irrelevant areas in the stripe image. Additionally, an improved Steger algorithm is proposed, which utilizes the grayscale centroid method to filter out invalid center points in the stripe direction. Experimental results show that, compared to traditional small-sample fully convolutional networks, the attention U-net achieves higher accuracy in extracting the stripe centerline, with a mean squared error (MSE) of only 5.3544 pixel, a peak signal-to-noise ratio (PSNR) of 40.8437 dB, and a structural similarity index (SSIM) of 0.9801%. At the same time, the improved Steger algorithm effectively corrects extraction deviations at the edges of the stripe.

This paper proposed a mathematical model for design and optimization of spatial optical phased array (SOPA) systems. Based on the theoretical models of one-dimensional (1D) and two-dimensional (2D) optical phased array (OPA), a theoretical model of Pseudo-three-dimensional (3D) OPA or SOPA is derived, which is employed to increase the arrangement density of radiation sources. The feasibility of the SOPA system is discussed based on the simulation results. Besides, the uniform distribution of the SOPA in the far field is realized to improve the precision of the OPA when scanning target objectives. The research work realizes an OPA scanner with a simple principle and wide angle, which will contribute to the development of OPA systems.

As an important tool for obtaining information on the Earth and outer space, the accuracy and performance of space remote sensors are directly related to the quality and reliability of remote sensing data. The alignment and adjustment of optical systems is a crucial step in ensuring the performance of remote sensing sensors. As a non-contact and digital measurement method,3D measurement technology has a wide and in-depth application in the field of optical alignment and adjustment, playing a key role in improving assembly accuracy and development efficiency. 3D measurement technology includes optical 3D measurement methods such as laser trackers, photogrammetric systems, and theodolites, et.

Fiber optic gyroscope is an inertial measurement device, has been used in aviation, aerospace and navigation fields widely. It’s easy affected by the vibration noise in the surrounding environment and the application scene. The vibration causes the stress of the fiber ring to change, pigtail vibration of the optical device and the structure resonance of the fiber gyroscope, These changes will affect the performance indexes of the fiber gyroscope, such as zero bias and zero bias stability. Filter method is added to the data processing of fiber optic gyro in paper, and the vibration noise data is filtered by adaptive adjustment of filter parameters. To a certain extent, the influence of vibration and noise on the performance of fiber optic gyroscope is reduced, the zero bias drift is reduced, and the zero bias stability of fiber optic gyroscope is improved after filtering.

This short invited paper reviews part of recent developments in designing and fabricating actively morphed thin-shell reflectors with unimorph actuators, which hold potential for use in space, particularly for large-aperture applications in space observation and communication. The discussion covers several technological updates and iterations and highlights complementary aspects relative to the existing literature on their applications.

The signal processing circuit of the fiber optic gyroscope adopts a digital closed-loop processing scheme. It modulates the Y-waveguide integrated optical device through a D/A converter and its amplification circuit and demodulates the optical signals containing angular rate information via the detector signal processing circuit and A/D converter. The angular rate sensed by the fiber optic gyroscope is then calculated by a digital signal processing logic chip FPGA. Traditional fiber optic gyroscopes predominantly use imported components such as operational amplifiers, FPGAs, and A/D and D/A devices. In response to the urgent demand for gyroscopes with specific sizes and 100% domestic production, and with the gradual maturity of domestic integrated electronic components, the optimized design of the main control signal processing board, component selection, and the comprehensive application of flexible lamination technology have ensured that the accuracy and performance of the fiber optic gyroscope are maintained even with full domestic circuit production and reduced size.

The off-axis three-mirror optical system is a typical class of off-axis systems. In order to ensure excellent imaging quality in the full field of view, the alignment process involves multiple components with multiple degrees of freedom which is difficult and challenging. This article focuses on the research of automatic adjustment technology for the off-axis three-mirror optical system. By quantitatively studying the relationship between component misalignment and aberrations, we aim to explore alignment method for this type of system, providing effective and reliable methods for active adjustment. The method studied in this paper has been verified on an off-axis three-mirror optical system, achieving a full-field RMS better than 0.05@632.8nm, reaching the diffraction limit.

Deterministic polishing is critical to the fabrication of ultra-precision aspheric optics, where precise dwell time algorithms are used to remove surface material. However, the sub-aperture polish removal function introduces surface ripple characteristics and degrades optical performance due to its narrow full width at half maximum and mismatched spatial wavelengths, reducing volume removal rate and introducing high and medium spatial frequency errors on the surface. Therefore, there is an urgent need to introduce pre-processing and post-processing to improve flexibility control in deterministic small tool polishing, enhance the adaptability of the tool to the workpiece surface with changing curvature, and obtain a stable Gaussian-like tool influence function. This paper explores the surface finishing removal mechanism based on the compliant figuring process and verifies the robustness and machining accuracy of the tool influence function for plane and variable curvature Nickel-phosphorous alloy machined surfaces. Firstly, based on the removal mechanism of the figuring process, the relative velocity and contact pressure models were established. Secondly, the influence of the radius of curvature and the amount of offset on the removal function is discussed. Finally, the high frequency band and middle frequency band of the one-dimensional power spectral density curve are analyzed in detail, and the reliability and modification ability of the compliant figuring process are verified according to the amplitude spectrum image.