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Within the framework of inverse problems of photometry, we study questions on reconstruction of the spatial location and luminosity of a Lambertian optical surface from its images obtained with the use of a small number of optical systems. We study causes of ambiguity in reconstruction of the location of such a surface. We suggest criteria for existence of a unique solution of the inverse problem on reconstruction of a luminous surface from three images for general weight functions and apply the results to specific classes of weight functions that model the degree of transparency of the medium (including its absorption or scattering). [ABSTRACT FROM AUTHOR]

Terahertz imaging has significant development prospects in terahertz technology due to its strong penetration and high spatial resolution. Currently, optical system designs are generally limited to the visible light range. To design an optical system suitable for terahertz imaging, an analysis of optical materials and system structures has been conducted. TPX (4-methylpentene-1) material and inverse telephoto structure were selected as the design basis. A terahertz optical system with a full field angle of 50°, a relative aperture of 1/4 and a focal length of 100 mm is designed using ZEMAX. The optimization results show that the root mean square radius of the spot in each field of view is smaller than the airy disk radius, indicating good imaging quality of the system. [ABSTRACT FROM AUTHOR]

To meet the spatial perception requirements for autonomous ship navigation in common scenarios such as ocean navigation, port entry and exit, and lock passage, commercial vehicle-mounted LiDAR technology falls short of demands in aspects such as sensing distance, field of view, angular resolution, and spatial sampling density. This paper proposes a hundred-beam-scale LiDAR scheme based on large-field-of-view diffractive beam splitting and a fiber array for echo reception and presents an in-depth investigation of the angular nonuniformity of diffractive beam splitting and the microradian-scale alignment for such hundred-beam-scale large-field-of-view LiDAR. This paper considers a combination of split-beam transmission based on a high-order diffractive optical element (DOE) and echo reception based on a high-precision fiber-optic line array. The nonlinear angular characteristics of the DOE are deduced and analyzed for a large field of view. The units of the receiving fiber-optic array are designed to offset the influence of the angular nonlinearity of the DOE, ensuring high-precision receiver–transmitter alignment of the hundred-beam-scale LiDAR for beams at any order of diffraction and helping to reduce system errors. The above-described LiDAR system has undergone laboratory testing and practical engineering verification, and it provides a new optical solution for LiDAR systems at the hundred-beam scale with a large field of view, a small divergence angle, and high sampling density. The presented system achieves a registration accuracy of 66.5 μrad with 128 beams and a 10-degree field of view, greatly improving signal reception efficiency. Such LiDAR systems have a wide range of applications, including space docking, target identification, lunar and planetary exploration, and ground-based vehicle-mounted LiDAR. [ABSTRACT FROM AUTHOR]

Apodization of pupil with various amplitude filters have been investigated for altering the point spread function for diffraction-limited optical systems' pictures of point objects by employing various filters, such as connes and tringle filters. We have shown that, for different levels of amplitude apodization, the lower values. An observation that these filters give good results for lower values of the apodization parameter. (FWHM) Full width at half maximum of the point spread function (PSF) is smaller than the Airy PSF, improving the performance of the optical system. [ABSTRACT FROM AUTHOR]

The article gives a brief description of the Sun-Terahertz space experiment scheduled for 2024–2025 aboard the Russian segment of the International Space Station. This experiment is aimed at studying the Sun within the previously unexplored terahertz range, obtaining data on terahertz solar radiation, as well as studying solar active regions and solar flares. The authors consider scientific equipment being developed for the Sun-Terahertz experiment, which comprises eight detection channels that are sensitive to radiation of different frequencies within the range of 0.4–12.0 THz. Each channel includes an optical telescope, a system of series filters, an optical chopper, and a radiation receiver with an opto-acoustic detector—Golay cell. The change in the sensitivity of Golay cells with a change in their intrinsic temperature (temperature effect) was studied. By means of auxiliary equipment—a test bench comprising a single-channel mockup and a blackbody simulator—the linear section of the temperature dependence of Golay cells was determined. A procedure was developed to compensate for the temperature effect in Golay cells, and the results of piloting the procedure on the test bench were presented. The proposed procedure can be useful in the development of scientific equipment comprising Golay cells, which is expected to be used under ambient temperature fluctuations. [ABSTRACT FROM AUTHOR]

Copyright of Chinese Medical Equipment Journal is the property of Chinese Medical Equipment Journal Editorial Office and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

In this study, we design an ultra-low self-heating radiation long-wave infrared laser communicationoptical system, which mainly includes aperture stop, primary mirror, secondary mirror, three-mirror,field stop, four-mirror, window glass, detector light shield, and image plane. The system enters apupil diameter of 280 mm, a field of view angle of 1×1°, a system focal length of 840 mm, and awavelength of 8 − 12 μmkm; the off-axis four-fold anti-structure is adopted. The optical mirror andstructural components of the material are Aluminum, the system's own thermal radiation equivalent toa black-body temperature of 171 K. The equivalent black-body temperature of the system is measuredin a vacuum chamber. The temperature of the spacer is 100 – 120 K, the temperature of the coldplate is 85 – 87 K, and the integration time is 550 – 800 μs. At this time, the measured equivalentblack-body radiation temperature of the system is 172.9K; it is consistent with the simulation value.The design scheme solves the technical problems of low signal-to-noise ratio, poor image contrast, andshort detection distance of infrared laser communication system. [ABSTRACT FROM AUTHOR]

Laser processing is a versatile tool that enhances smart materials for diverse industries, allowing precise changes in material properties and customization of surface characteristics. It drives the development of smart materials with adaptive properties through laser modification, utilizing photothermal reactions and functional additives for meticulous control. These laser-processed smart materials form the foundation of 4D printing that enables dynamic shape changes depending on external influences, with significant potential in the aerospace, robotics, health care, electronics, and automotive sectors, thus fostering innovation. Laser processing also advances photonics and optoelectronics, facilitating precise control over optical properties and promoting responsive device development for various applications. The application of computer-generated diffractive optical elements (DOEs) enhances laser precision, allowing for predetermined temperature distribution and showcasing substantial promise in enhancing smart material properties. This comprehensive overview explores the applications of laser technology and nanotechnology involving DOEs, underscoring their transformative potential in the realms of photonics and optoelectronics. The growing potential for further research and practical applications in this field suggests promising prospects in the near future. [ABSTRACT FROM AUTHOR]

Copyright of Chinese Medical Equipment Journal is the property of Chinese Medical Equipment Journal Editorial Office and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

To build a long-wave infrared catadioptric optical system for deep space low-temperature target detection with a lightweight and wide field of view, this work conducted a study that encompasses a local cooling optical system, topology optimization-based metal mirror design, and additive manufacturing. First, a compact catadioptric optical system with local cooling was designed. This system features a 55 mm aperture, a 110 mm focal length, and a 4-degree by 4-degree field of view. Secondly, we applied the principles of topology optimization to design the primary mirror assembly, the secondary mirror assembly, and the connecting baffle. The third and fourth modes achieved a resonance frequency of 1213.7 Hz. Then, we manufactured the mirror assemblies using additive manufacturing and single-point diamond turning, followed by the centering assembly method to complete the optical assembly. Lastly, we conducted performance testing on the system, with the test results revealing that the modulation transfer function (MTF) curves of the optical system reached the diffraction limit across the entire field of view. Remarkably, the system's weight was reduced to a mere 96.04 g. The use of additive manufacturing proves to be an effective means of enhancing optical system performance. [ABSTRACT FROM AUTHOR]

Background. Designing an arbitrary afocal zoom optical system is a complex and multidimensional problem. It cannot be solved analytically and requires the essential experience and efforts of the designer. Objective. The purpose of the paper is to present and verify by simulation the method and means to perform an automated design of complex multi-lens afocal zoom optical systems having variable parameters and characteristics. Methods. Using the developed specialized software with implemented modification of the adaptive Cauchy differential evolution algorithm for the parametric synthesis of multi-component optical systems of zoom riflescopes with extended functional parameters. Results. The developed optical system of the riflescope provides the 5× magnification ratio and the angular field of view in the object space from 3.26° to 0.83°. It has a reticle located in the first focal plane, the entrance pupil diameter of 60 mm, the eye relief within the range of 106...111 mm, and the maximum system length of 390 mm. The riflescope contains 13 lenses in 10 components. The performed simulations showed that the time interval required for the direct automated design of the riflescope’s optical system is about 30–40 hours for the total number of unknown parameters (variables) equal to 91. The root-mean-square values of the angular aberrations of axial beams in all (five) configurations of the synthesized zoom system do not exceed 1.25 arc minute in the whole spectral range. The algorithm helps to determine the prescription data of optical systems, considering the technical requirements and restrictions specified by the designer. Conclusions. Computer simulations of the development of the zoom riflescope with the magnification of 5-25×, the entrance pupil diameter of 60 mm, and the reticle located in the first focal plane have confirmed the effectiveness of the proposed algorithm to design automatically complex multi-lens optical systems with variable parameters. The obtained results proved the high image quality of the generated 13-lens riflescope with the long eye relief. The implemented modification of the adaptive Cauchy differential evolution method can be considered a powerful tool that helps to automate the parametric synthesis of multicomponent optical systems of zoom riflescopes, taking into account the requirements set by the designer. Future research should test the feasibility of the automated design of other riflescopes containing more lenses and providing extreme performances.

The article describes Schlieren photography, realised using a laser plasma as a radiationsource. Optical systems prepared for visualisation of a stationary gas outflow and a pulsed gaseoustarget, produced in an atmosphere or vacuum environment are presented. A He-Ne laser beam orlaser plasmas were used as the light sources. Schlieren images of outflows of helium, carbon dioxide,krypton, nitrogen and sulphur hexafluoride, are presented. A comparison of various gas streams,formed in atmosphere, imaged using different light sources are shown. Schlieren images of a twostreamgaseous target formed in vacuum are also presented.Keywords: automation, electronics, electrical engineering and space technology, refraction, opticalsystem, laser plasma, schlieren photography

The infrared search and track system (IRST) is a type of special electrical optical (EO) system that can be used in various scenarios to fulfill situation awareness, reconnaissance, and tracking of targets. We proposed a homogeneous coordinate transformation method to analyze the residual image wandering induced by the rotation of the scanning platform and the compensation fast steering mirror and help with the commonly trivial selection of the telescope magnification and the objective focal length. The analysis and simulation are carried out with specified IRST optics, which adopt a 640 × 512 array and 15 μm pitch detector, in a focal range of 60 mm~360 mm, and a scan speed of 360°/s to 60 °/s at 50 fps, and optical specifications are determined further. The presented optical system, with only three kinds of common infrared materials, works at 3.7 μm~4.8 μm, demonstrates good image performance and tolerance characteristics, and shows potential in manufacturing. Also, the resulting image wandering of 8 μm, less than a 0.6-pixel size, at an integral time of 16 ms, proves the correctness of the method and makes the scheme of considerable interest for electrical optical systems. [ABSTRACT FROM AUTHOR]

The work was dedicated to the laser modules for the spectral range of 975 nm based on single laser diodes with fiber output to be designed and manufactured. The installation of an optical system for the seven laser diodes radiation input into a silica-silica fiber with a core diameter of 105 μm and a numerical aperture of 0.15 has been carried out while investigating their power and spectral characteristics. The maximum output power of the laser module was 65 W in CW operation at a nominal current of 12 A and a thermal stabilization temperature of 25°C, the total efficiency of the laser module was 43%, and the brightness of the laser module amounted to 10.6 MW/(cm2 sr). [ABSTRACT FROM AUTHOR]

Introduction: The geometrical precision of the machines is essential for effective and safe radiotherapy. Methods currently used for the measurement of the mechanical isocenter have many limitations. In this work, the optical system NaviRation for very precise measurement of mechanical accelerator isocenter is described. The results of the measurement of the isocenter for linear accelerator are also presented. Materials and methods: An optical system for measuring the accelerator isocenter was designed and built. The optical system consists of two cameras recording the target position made according to a patented Zeiss technology. About 1,200 pairs of images are recorded during the rotation of the gantry, collimator and treatment table. Mathematical analysis of these images makes it possible to determine the location of the target center during rotation. In order to verify the accuracy of the measurements, a device simulating rotational motion was designed. The measurement results were also verified at the Central Office of Measures. The system must be calibrated each time before taking measurements. In this article, we present the results of measurements for the Versa HD accelerator. Results: The accuracy of determining the current position of the axis of rotation was 0.15 mm. The time of taking measurements of all rotations does not exceed 20 minutes. Measurement results for the Versa HD accelerator showed that this accelerator met the criteria described by TG142 of the AAPM. The diameter of the gantry, collimator and table isocenter spheres were 1.5 mm, 0.3 mm and 0.4 mm, respectively. Conclusions: The system enables precise, fast and simple mechanical isocenter measurement of the gantry, collimator and treatment table. It is also possible to perform all tests related to the measurements of distances, e.g. quality control of distance indicator, and distance of the table movement. The isocenter is measured independently of the accelerator for which measurements are made. [ABSTRACT FROM AUTHOR]

Within the framework of geometric tomography, inverse problems of photometry, wave optics, and discrete tomography, we study questions on reconstruction of the spatial location and luminosity of a discrete distribution of radiant sources from its images obtained with the use of a small number of optical systems. We analyze the problem on finding geometric parameters of such a distribution and describe sources of ambiguity. We consider the inverse problem on reconstruction of a discrete distribution that consists of incoherent and monochromatic sources and suggest uniqueness criteria for its solution. We also suggest a constructive approach to numerical solution of the inverse problem on reconstruction of the coordinates and luminosity of a family of radiant pinpoint sources from their images. [ABSTRACT FROM AUTHOR]

Laser radiation produces an effect that is mainly determined by the ability of the optical system to create a given energy distribution over the worked surface of the material. The variety of existing and developing optical systems indicates the importance of solving this problem. The use of computer optics elements for redistribution of laser intensity in the focal plane is also important. This largely determines the course of structure formation processes in processed materials. The features of synthesis of porous and oxide nanostructures by laser irradiation are considered. When frequency-modulated laser beam is used, the synergistic effect between the thermal effects of laser irradiation and the pulse-periodic laser-induced vibrations leads to a significant increase in the diffusion coefficient. This is caused by the non-stationary stress-strain state of the material to be treated. [ABSTRACT FROM AUTHOR]

Current photoacoustic systems face a technical bottleneck in terms of image resolution at the clinical level. Therefore, various methods in the optical system are proposed for improving resolution while processing acoustic signals. To improve the image resolution, a novel optical system design for a telecentric collimator optical system needs to be developed. The telecentric collimator system with three different cases (zoom 1, zoom 2, and zoom 3) was developed with different focal length variances. The designed telecentric collimator optical system can obtain a telecentric angle of 0.3° and maximum diffraction aberration of less than −0.27%. Therefore, we can conclude that a designed telecentric collimator design can be useful for improving the image resolution of the photoacoustic system at the target surface because the designed collimator optical system can provide a very small telecentric angle variance over a wide range. [ABSTRACT FROM AUTHOR]

The projection stellar target simulator is a stellar target simulator in which star points are projected to be imaged on a fixed plane at a fixed distance. Compared with conventional stellar target simulators, the projection stellar target simulator makes star points visible and provides the necessary condition for a semi-physical simulation test of the star camera. In this paper, the projection stellar target simulator optical system with high-quality imaging is designed by combining the projection technology, which breaks the collimated imaging of the conventional stellar target simulator optical system, and offers a new thought to solve the problem of decreasing the calibration accuracy caused by the influence of the coaxiality and other factors in the stellar target simulator calibrating the star camera. Based on the imaging behavior of the star map, this paper proposes a method to realize the automatic detection of a projection stellar target simulator by using CCD and introduces the composition and working principle of the detection system in detail. According to the imaging characteristics of star points, denoising and threshold segmentation of the star map are carried out, and an improved centroid algorithm is proposed to achieve high-precision positioning of the centroid coordinates of the star points. The measurement model and measuring formulas for the angular distance between stars are established. The error sources of the detection system are analyzed and obtain the theoretical error of 9.22″ for this detection system. The result of an actual test experiment shows that the position error of single star is less than 11″, in line with the theoretical analysis of the error, indicating the detection system has high detection precision and meets the requirement for the detection accuracy of the projection stellar target simulator. [ABSTRACT FROM AUTHOR]

Spherical aberration is an imperfection of the optical system of the human eye. The role of spherical aberration of the human eye in the quality of vision and pseudoaccommodation is reviewed. Spherical aberration is an imperfection of the optical system of the human eye. In most cases, due to well-developed neuroadaptation, it is insignificant for the perception of the image. Nevertheless, its role in modern ophthalmology is far from straightforward. On the one hand, there are clinical scenarios in which an excess of spherical aberration degrades the retinal image and leads to a high dissatisfaction rate among patients.©Recently, there is a growing interest in the modulation of spherical aberration in the clinical setting. Modern intraocular lenses as well as laser refractive procedures are aimed at interfering with spherical aberrations of the optical system in order to increase range of pseudoaccommodation. Here, we review the role of spherical aberration of the human eye in the quality of vision and pseudoaccommodation. [ABSTRACT FROM AUTHOR]

The detection and observation of space debris in Low Earth Orbit is generally carried out through the use of ground based radars and telescopes. These instruments allow for a precise reconstruction of the space debris trajectories, and therefore represent a key asset for planning avoidance maneuvers when threats of collisions are predicted. The recent deployment of mega-constellations, with the consequent increase of the number of satellites, imposes new challenges in terms of simultaneous tracking capability and readiness of the current space situational awareness systems. This adds to the current need to track small and dull objects to further mitigate the probability of triggering cascade collisions. However, ground based observations are limited due to their intrinsic sensibility to atmospheric refraction, their diurnal inoperability and their dependence on meteorological hazards. This paper proposes to study the feasibility and the benefits of a potential deployment of a constellation of CubeSats in Low Earth Orbit, to acquire optical observations of space debris with enhanced accuracy, as part of the ORCA mission: Orbit Refinement for Collision Avoidance. Here, the focus is on the optical design of the payload instrument to be integrated onboard of the orbiting platforms. The study trades-off the current state-of-art of optical detection technologies, by assessing their performance against a set of specific requirements: (a) the minimization of the uncertainty associated to the image resolution; (b) a field of view that maximizes the extent of the monitored area; (c) an optimal exposure time to avoid under or overexposure of the image; (d) minimization of the effects of light diffraction and above all, (e) the maximization of the signal to noise ratio to detect the smallest and dullest objects possible. Several configurations of optical systems are then chosen as suitable for the ORCA constellation, also considering the system design implications of its integration into a CubeSat, such as size requirements. Commercial Off-The-Shelf hardware are explored and performances of the optical system are evaluated through numerical simulations in order to estimate the detectable sizes of space debris while taking into account their potential distances from the sensor. This paper concludes with estimates of the impact of the ORCA mission on space situational awareness for decades to come. • We defined requirements for an optical system for space debris surveillance. • We formulated conditions allowing detection of space debris from optical images. • We explored feasible design of optical systems for a CubeSat size implementation. • We compared our results with available commercial-off-the-shelf optical systems. [ABSTRACT FROM AUTHOR]

Military personnel in the training or operational phases always need constant medical examination, but the presence of efficient medical care is difficult to implement in real-time for such cases. A wireless system for thermal tracking of soldiers was proposed, as well as tracking their vital signs in real time. Thermal cameras are used with an optical system designed to increase the accuracy of the thermal images captured as the change in the electrocardiogram, heart rate, and temperature measurements are measured using a specially designed circuit. The results from both the thermal system and the biometric system are combined and sent to a computer for analysis using a model prepared with neural network technology. The proposed system was tested, and a database was created for 127 males and 110 females during training and rest times. The neural network model achieved a response time of 85 seconds until the release of the final analysis, and the accuracy of the proposed tracking system is 96%. The main contribution of this paper is the design of an integrated portable system for rapid, in-field, real-time military medical diagnostics. [ABSTRACT FROM AUTHOR]

With the development of science and technology, aspherical surface has become an indispensable component in optical system. However, the aspheric surface has more complex optical properties than the spherical surface, so it restricts the rapid development of aspheric surface. In this paper, the main problem of aspherical machining is analyzed, which is"Trajectory control", and the unique optical properties of aspherical surface are analyzed, a trajectory control algorithm based on genetic-BP neural network is proposed to solve the trajectory control in aspheric forming. The method is proved to be feasible and effective. [ABSTRACT FROM AUTHOR]

Image geometric distortion is common in a large field of view optical system. It becomes a technical difficulty for high distortion rate optical systems and high resolution image geometric distortion correction. But, a crucial step in distortion correction is figuring out how to precisely obtain the index coordinates and correction parameters, otherwise known as the lookup table. In this paper, the problems in the traditional lookup table method are analyzed, and an improved lookup table method is proposed. The method is based on the traditional lookup table method with the addition of removing the wrong data of position coordinates in the correction image feature points, calculating the ideal image feature point position coordinates, handling the index coordinate out-of-bounds, and adjusting the output order of index coordinates and correction parameters. The experimental results show that the improved design method is feasible, and improves the accuracy of the correction image, compared with the traditional lookup table, the root mean square error is reduced by 93%, and the average accuracy of the fitted position over the full field of view is reduced by 51.9%, and the maximum deviation is only 0.2917%. For the correction of the large field of view optical display devices, it offers good correction effects.

Diffractograms of rotated polyaniline fiber grating were studied experimentally. Based on the obtained results, the diffraction patterns were analyzed and set of experimental data obtained after image digitization was approximated by the least squares method. The angle of rotation of the diffraction grating was calculated using the determined coefficients of the second-order curves.

This method is a variant of non-destructive multiparametric surface analysis and includes the implementation of hyperspectral and RGB image processing approaches from different angles. This work is based on a fundamental hyperspectral survey system for obtaining data on scanned biological objects in many spectral ranges and with several possible variants of assembling a system with different types of surface illumination with point light and diffuse illumination. The implementation of the technology through the use of a diffused light source provides the diffuse illumination of a biological object with pronounced symptoms of rarefaction on the surface of a biological object—in this case, potato tubers, due to the presence of signs of disease on the potato peel, as well as their deformation. Using broadband lamps, a short-pass filter is located between the source and the object (λ ≤ 400 nm, λ may vary depending on the excitation length), and a long-pass filter (λ ≥ 400 nm) between the root or onion and the chamber. The use of a vision system with a created database containing models of real defects in potato tubers showed a high sorting efficiency, providing an accuracy of sorting by size of 95.4%, and an accuracy by the presence of defects of 93.1%. [ABSTRACT FROM AUTHOR]

Due to the geographical location and natural climatic conditions, solar energy has a priority in Kazakhstan among all renewable energy sources. Some regions of Kazakhstan experience more than 270–300 sunny days per year, making it possible to utilize solar energy almost all year round. In this regard, there is a need for the development and implementation of large-scale solar technology. In this study, a comprehensive review and analysis of modern solar technology structures were conducted. The primary focus of this research lies in the following tasks: developing operational modes through computer simulation, modeling the structure of the focal spot in the optical system, and exploring the potential of employing contemporary digital and computer technologies. The optimization issues and computer simulation of the operating modes of the optical system in a tower-type solar power plant are considered in more detail. A calculation scheme and a mathematical model have been developed to estimate the local values of the efficiency coefficient (η) for the use of a mirror surface of the heliostat field. The results are visually presented in the form of a map for local values of the efficiency coefficient (η) of using the mirror surface of the heliostat field in tower-type solar power plants. [ABSTRACT FROM AUTHOR]

We report on an optical setup to generate multi-Bessel beam profiles combining a refractive axicon and a spatial light modulator. Based on their particular beam profile, Bessel beams offer advantageous properties for micro drilling processes and internal volume processing, especially for transparent materials. In addition, the laser power of industrial, ultrashort pulsed lasers has increased significantly over the last few years, offering the possibility for highly efficient processes using multi-spot profiles. Our optical concept combines the dynamic possibilities of beam splitting using a spatial light modulator with the benefits of Bessel beams, which facilitates multi-Bessel beam processing. Beside the simulation and experimental evaluation of the generated multi-Bessel beams, we exemplify the applicability of the developed module for the perforation of thin metal foils by micro drilling. [ABSTRACT FROM AUTHOR]

To build a long-wave infrared catadioptric optical system for deep space low-temperature target detection with a lightweight and wide field of view, this work conducted a study that encompasses a local cooling optical system, topology optimization-based metal mirror design, and additive manufacturing. First, a compact catadioptric optical system with local cooling was designed. This system features a 55 mm aperture, a 110 mm focal length, and a 4-degree by 4-degree field of view. Secondly, we applied the principles of topology optimization to design the primary mirror assembly, the secondary mirror assembly, and the connecting baffle. The third and fourth modes achieved a resonance frequency of 1213.7 Hz. Then, we manufactured the mirror assemblies using additive manufacturing and single-point diamond turning, followed by the centering assembly method to complete the optical assembly. Lastly, we conducted performance testing on the system, with the test results revealing that the modulation transfer function (MTF) curves of the optical system reached the diffraction limit across the entire field of view. Remarkably, the system’s weight was reduced to a mere 96.04 g. The use of additive manufacturing proves to be an effective means of enhancing optical system performance.

We propose a new scheme for optical quantum simulation of topological systems: by using optical systems to simulate the variation of eigenstates of topological systems in momentum space, we can obtain the information of topological numbers. In this paper the scheme is applied to the one-dimensional (1D) Su–Schrieffer–Heeger (SSH) model and the two-dimensional (2D) Bernevig–Hughes–Zhang (BHZ) model. In addition, in order to apply our scheme to 2D topological systems, we design a method of calculating topological numbers by line integral. Furthermore, we propose a more effective optical simulation scheme for the 2D topological system: we do the optical simulation around discontinuity points to obtain the vorticity of every discontinuity points and the topological number is just the sum of the vorticity of all discontinuity points.

The long-term sustainability of the Additive Manufacturing (AM) industry not only depends on the ability to produce parts with reproducible quality and properties to a large extent but also on the standardization of the production processes. In that regard, online process monitoring and detection of defective parts during production become inevitable. Optical-based process monitoring techniques are popular; however, most work has been mainly focused on capturing images of print abnormalities without taking other influencing factors, such as camera and part position, chamber illumination, and print geometry on the resolution of the captured images, into account. In this work, we present a scenario to evaluate and quantify the performance of an optical-based monitoring system in a Laser Powder Bed Fusion (LPBF) machine using the F1 score, considering factors such as scan vector orientation, part geometry (size) and position in a built chamber with a fixed camera position. The quantified results confirm that the F1 score can be used as a reliable means of evaluating the performance of optical-based monitoring systems in the LPBF process for the purposes of standardization. The biggest line width of the test artifact (1000 µm) had the highest F1 score range of 0.714–0.876 compared to the smallest (200 µm) with a 0.158–0.649 F1 score. [ABSTRACT FROM AUTHOR]

With the emerging development of hyperspectral single-pixel imaging (SPI) systems, the trade-off between the simplicity of optical structure and the correction of chromatic aberration is now an essential factor to be considered. To address both issues simultaneously, we propose a chromatic-aberration-corrected hyperspectral single-pixel imaging scheme, which is based on spectral measurement and dispersion correction. Its achromatism feature is evaluated by optical simulations and proof-of-concept experiments. Moreover, to overcome the shortcomings of traditional algorithms, a new adaptive iterative algorithm is employed, which can further optimize image quality. The results demonstrate that both dispersion and noise in our system are significantly reduced. Taking the position coordinate variance as a figure of merit, we have realized an order of magnitude improvement in the lateral chromatic aberration over the spectral range of 400–780 nm compared to that in conventional hyperspectral SPI. Meanwhile, the contrast-to-noise ratio in our system is enhanced on average by 3 dB. To the best of our knowledge, this is the first such demonstration, and the technique presents possibilities for future integrated applications of high spatial/spectral resolution over the entire visible range, and the system has the potential to be scaled down for future integrated applications. [ABSTRACT FROM AUTHOR]

The steering mirrors and the focusing mechanisms are the key components of the optical system. Traditional steering mirrors driven by voice coil actuator or piezoelectric stack actuator have the disadvantages of short stroke, self-locking difficulty and poor structural reliability. These defects limit the performance of the steering mirrors and make it difficult to be compatible with the focusing mechanism. As a result, additional focusing devices are required in the optical system, which significantly increases the complexity of the system. To simplify the optical system, a large stroke three-degree-of-freedom (3-DOF) piezoelectric steering mirror (PSM) which can realize both light path adjustment and focus adjustment is proposed in this study. Two rotational degrees of freedom of the PSM are used to adjust the light path, and a translational degree of freedom is used to adjust the focus. The screwed-typed piezoelectric actuators (STPAs) are designed to drive the PSM by exciting the travelling wave. The feasibility of the operating principle and reliability of the proposed PSM have been verified by finite element simulation. A prototype of the PSM is fabricated and tested. The experimental results show that the PSM achieves rotational degrees of freedom around the x -axis, y -axis and translational degree of freedom along the z -axis with maximum ranges of ±0.17 rad, ±0.17 rad, and ±10 mm, respectively, meeting the application requirements of the optical systems. The resolutions of the two rotary motions of the PSM are 28 μrad, and 21 μrad, respectively, and that of the translational motion is 0.5 μm. Finally, the position adjustment and focusing operations of the image are demonstrated to validate the potential application of PSM in optical systems. [Display omitted] • A large-stroke high-precision fast-response screwed-typed piezoelectric actuator (STPA) is designed in this study. • A novel 3-DOF piezoelectric steering mirror is proposed to realize the light path adjustment and focusing functions. • The proposed PSM is verified to adjust the image position adjustment and focus adjustment. [ABSTRACT FROM AUTHOR]

The infrared search and track system (IRST) is a type of special electrical optical (EO) system that can be used in various scenarios to fulfill situation awareness, reconnaissance, and tracking of targets. We proposed a homogeneous coordinate transformation method to analyze the residual image wandering induced by the rotation of the scanning platform and the compensation fast steering mirror and help with the commonly trivial selection of the telescope magnification and the objective focal length. The analysis and simulation are carried out with specified IRST optics, which adopt a 640 × 512 array and 15 μm pitch detector, in a focal range of 60 mm~360 mm, and a scan speed of 360°/s to 60 °/s at 50 fps, and optical specifications are determined further. The presented optical system, with only three kinds of common infrared materials, works at 3.7 μm~4.8 μm, demonstrates good image performance and tolerance characteristics, and shows potential in manufacturing. Also, the resulting image wandering of 8 μm, less than a 0.6-pixel size, at an integral time of 16 ms, proves the correctness of the method and makes the scheme of considerable interest for electrical optical systems.

Purpose of this work is to study the initial-boundary value problem for a parabolic functional-differential equation in an annular region, which describes the dynamics of phase modulation of a light wave passing through a thin layer of a nonlinear Kerr-type medium in an optical system with a feedback loop, with a rotation transformation (corresponds the involution operator) and the Neumann conditions on the boundary in the class of periodic functions. A more detailed study is made of spatially inhomogeneous stationary solutions bifurcating from a spatially homogeneous stationary solution as a result of a bifurcation of the “fork” type and time-periodic solutions of the “traveling wave” type. Methods. To represent the original equation in the form of nonlinear integral equations, the Green’s function is used. The method of central manifolds is used to prove the theorem on the existence of solutions of the indicated equation in a neighborhood of the bifurcation parameter and to study their asymptotic form. Numerical modeling of spatially inhomogeneous solutions and traveling waves was carried out using the Galerkin method. Results. Integral representations of the considered problem are obtained depending on the form of the linearized operator. Using the method of central manifolds, a theorem on the existence and asymptotic form of solutions of the initial-boundary value problem for a functional-differential equation of parabolic type with an involution operator on an annulus is proved. As a result of numerical modeling based on Galerkin approximations, in the problem under consideration, approximate spatially inhomogeneous stationary solutions and time-periodic solutions of the traveling wave type are constructed. Conclusion. The proposed scheme is applicable not only to involutive rotation operators and Neumann conditions on the boundary of the ring, but also to other boundary conditions and circular domains. The representation of the initial-boundary value problem in the form of nonlinear integral equations of the second kind allows one to more simply find the coefficients of asymptotic expansions, prove existence and uniqueness theorems, and also use a different number of expansion coefficients of the nonlinear component in the right-hand side of the original equation in the neighborhood of the selected solution (for example, stationary). Visualization of the numerical solution confirms the theoretical calculations and shows the possibility of forming complex phase structures.

Results of numerical and experimental studies on monitoring and control for optical elements of an electric discharge KrF laser by the method of density-based spatial clustering of applications with noises (DBSCAN) are presented. Different methods of processing digital signals obtained using a position-sensitive detector controlling the position of the optical axis of the laser system are considered. A numerical model of optical system stability is developed based on the DBSCAN method with an additional inclusion of digital signal processing with the use of the cumulative moving average. A technique for correction of controlled mirrors with an accuracy of 60 ± 10 µrad for their return to normal position is proposed and implemented; the alignment time does not exceed 5 min. [ABSTRACT FROM AUTHOR]

As a technology that combines spectral technology and imaging technology, hyperspectral imaging technology can obtain the spectral and spatial information about the targets effectively. Hence, the underwater hyperspectral imaging technology has a fast development since it was first used underwater. Many kinds of hyperspectral imagers used for underwater detection at different depths were developed. However, the underwater hyperspectral imagers used at deep sea were rarely reported while the required detection depth increased. To satisfy the deep-sea exploration requirements, an underwater hyperspectral imaging system was designed. An optical system with a low F-number and a compact structure was first designed. The F-number of the system is 2.5. The focal length of the objective lens is 25 mm, and the field of view of the objective lens is 35.2°.The wavelength range of the system is from 400 to 1000 nm, and the spectral resolution of the spectrometer is better than 3 nm. The instrument cabin and other structures for waterproofing were designed. A minicomputer used for control communication, data acquisition, and processing was equipped in the actual system. The isolation performance and imaging quality were tested in the laboratory environment. According to the test result, the system has a good imaging quality and spectral detection capability. Also, the system can be used at 6000 m underwater, which may provide a new feasible technical scheme for deep-sea exploration.

The projection stellar target simulator is a stellar target simulator in which star points are projected to be imaged on a fixed plane at a fixed distance. Compared with conventional stellar target simulators, the projection stellar target simulator makes star points visible and provides the necessary condition for a semi-physical simulation test of the star camera. In this paper, the projection stellar target simulator optical system with high-quality imaging is designed by combining the projection technology, which breaks the collimated imaging of the conventional stellar target simulator optical system, and offers a new thought to solve the problem of decreasing the calibration accuracy caused by the influence of the coaxiality and other factors in the stellar target simulator calibrating the star camera. Based on the imaging behavior of the star map, this paper proposes a method to realize the automatic detection of a projection stellar target simulator by using CCD and introduces the composition and working principle of the detection system in detail. According to the imaging characteristics of star points, denoising and threshold segmentation of the star map are carried out, and an improved centroid algorithm is proposed to achieve high-precision positioning of the centroid coordinates of the star points. The measurement model and measuring formulas for the angular distance between stars are established. The error sources of the detection system are analyzed and obtain the theoretical error of 9.22″ for this detection system. The result of an actual test experiment shows that the position error of single star is less than 11″, in line with the theoretical analysis of the error, indicating the detection system has high detection precision and meets the requirement for the detection accuracy of the projection stellar target simulator.

In this study, by using motion capture technology in sports performances, it is aimed to develop mechanisms to detect physical condition, determine sports performance and prevent injuries by monitoring and recording the movements of athletes in real time. In this sense, sports biomechanics analysis is used to try to understand the relationship among kinetic and physical performance by looking at the physical aspects of performance. Biomechanical analysis enables to have a major impact on performance by creating models for optimum motion and load analysis. Therefore, this analysis can be used to determine the safest and most effective way to perform a skill, to study how the body moves or responds to a different environment. In this study, motion capture technologies used in sports biomechanics are classified in terms of hardware and software; The advantages and disadvantages of the studies on motion capture systems used in individual and team sports are revealed as regards sensors, the number of subjects, and the type of sport. In addition, matters such as image processing applications used in sports biomechanics, optical or non-optical systems, and data collection processes with or without markers has been handled. It is salient points that the effective and correct use of sports biomechanics plays an important role in athlete performance and athlete health, and makes significant contributions to the development of athlete-specific systems. We hope that this study can significantly guide studies in the field of biomechanics, especially sports biomechanics. [ABSTRACT FROM AUTHOR]

This method is a variant of non-destructive multiparametric surface analysis and includes the implementation of hyperspectral and RGB image processing approaches from different angles. This work is based on a fundamental hyperspectral survey system for obtaining data on scanned biological objects in many spectral ranges and with several possible variants of assembling a system with different types of surface illumination with point light and diffuse illumination. The implementation of the technology through the use of a diffused light source provides the diffuse illumination of a biological object with pronounced symptoms of rarefaction on the surface of a biological object—in this case, potato tubers, due to the presence of signs of disease on the potato peel, as well as their deformation. Using broadband lamps, a short-pass filter is located between the source and the object (λ ≤ 400 nm, λ may vary depending on the excitation length), and a long-pass filter (λ ≥ 400 nm) between the root or onion and the chamber. The use of a vision system with a created database containing models of real defects in potato tubers showed a high sorting efficiency, providing an accuracy of sorting by size of 95.4%, and an accuracy by the presence of defects of 93.1%.