2023

• Record 373 of
  
  Title:Development and performance evaluation of a far-ultraviolet sealed tube MCP photon counting imaging detector
  
  Author(s):Yang, Kai(1,2); Bai, Yonglin(1); Cao, Weiwei(1); Wang, Bo(1); Qiao, Zhu(1,2); Sun, Xin(1); Wang, Chao(1); Zhang, Shengdan(1,2); Bai, Xiaohong(1); Yang, Yang(1)
  Source: Proceedings of SPIE - The International Society for Optical Engineering  Volume: 12963  Issue: null  Article Number: 129631H  DOI: 10.1117/12.3007868  Published: 2023  
  Abstract:A photo-counting imaging sealed detector has been fabricated for far-ultraviolet (FUV) radiation detection, including an MgF2 input window, CsI photocathode, V-stack MCPs, circular arc terminated (CAT) resistive anode, and detector tube. The CsI photocathode was prepared by vacuum thermal evaporation. The CAT resistive anode was fabricated using thick-film technology. The detector body is mainly made of Kovar alloys and ceramics and was sealed in a cathode-transfer and indium-sealed vacuum system. The detector performance was evaluated using an FUV parallel light system consisting of a deuterium lamp, a reflective condenser, a filter wheel, a monochromator, a collimation system, and a vacuum chamber. The test results show that the imaging RMS nonlinearity is less than 3%, the spatial resolution is about 235um, and the dark. © 2023 SPIE. All rights reserved.
  Accession Number: 20240215330733
• Record 374 of
  
  Title:Optical System Design of MWIR Continuous Zoom Lens with High Zoom Ratio
  
  Author(s):Zhang, Hongbo(1); Yan, Aqi(2); He, Shuangliang(1); Zhang, Keyi(3); Wang, Hao(2)
  Source: Guangxue Xuebao/Acta Optica Sinica  Volume: 43  Issue: 12  Article Number: 1222002  DOI: 10.3788/AOS230537  Published: June 2023  
  Abstract:Objective Infrared (IR) imaging technology has become a research hotspot in different countries because of its advantages such as not being limited by day and night, being able to work all day, strong ability to penetrate smoke, and good detection concealment. In recent years, with the development of high-performance and high-resolution large-array IR detector technologies and the requirements of remote observation tasks such as border and coastal defense, various advanced IR imaging systems have emerged. The IR continuous zoom optical system is widely used in military and civilian fields. It can search for targets with a large field of view and observe distant targets with high resolution. In order to improve the IR system's ability to identify distant targets at long focal lengths while ensuring target search with a large field of view at short focal lengths, it is hoped that IR zoom optical system has a longer focal length and large zoom ratio. However, the longer focal length makes the diameter of the zoom optical system increase sharply. In addition to the inherent secondary spectrum, a large number of chromatic aberrations and advanced spherical aberrations in optical systems with long focal lengths will be introduced, which makes it difficult to design mid- wave infrared (MWIR) continuous zoom system with a large zoom ratio. Some scholars have also carried out relevant research and design work, but at present, the long focal length of the MWIR zoom system is less than 1000 mm; the detector resolution is mostly 640×512, and the optical path structure of the MWIR zoom optical system is complex and large. It is hard to meet the urgent demand of the new generation of photoelectric pods for high- definition MWIR zoom imaging systems with compact sizes. Methods In order to realize a compact design of IR zoom lens with a large zoom ratio, we propose a design idea and method which adopt secondary imaging, positive group mechanical compensation of zoom lens, and smooth root replacement and introduce a warm shield by switching the rear group of the zoom lens to change F- Number of the optical system at long focal length. The optical path of the MWIR zoom lens is ingeniously folded by two mirrors. First, the IR zoom optical system adopts a kind of optical path structure form with intermediate image planes and uses the zoom differential equation to solve the initial structure of the zoom lens to meet the required zoom ratio (Fig. 1); second, pupil aberration, especially pupil coma, is controlled in the optimization of the optical system to minimize the diameter of the front group; third, the optical system adopts positive group compensation zoom lens. It has a negative zoom group and a positive compensation group. The magnification of the zoom group and compensation group at a certain focal length position during optimization is controlled to keep zoom group magnification and compensation group magnification at − 1, so as to reduce zoom travel length and overall length of the MWIR zoom optical system as much as possible. Finally, two mirrors are cleverly used to fold the optical path, and by switching the rear group of the zoom lens, a warm shield is introduced to change F- number at a long focal length, which further reduces the diameter of the front group and keep IR zoom lens more compact. Results and Discussions Based on the proposed design method of a compact MRIR zoom lens, this paper uses a high-resolution MWIR- cooled detector with a resolution of 1280×1024. The pixel size is 15 μm, and an MWIR continuous zoom optical system with a zoom ratio of 48 times and focal length from 25 mm to 1200 mm has been designed (Figs. 2 and 3). While ensuring 100% efficiency of cold shield, the compact IR zoom lens is realized. The optical system has good imaging quality within the operating temperature range of − 40-60 ℃ (Fig. 6), and the maximum optical diameter of the front group is 230 mm. The total optical length after folding is only 350 mm. This compact MWIR zoom optical system has many advantages, such as a compact structure, large zoom ratio, long focal length, high resolution, and good imaging quality, which can meet the requirements of the new generation of IR imaging systems (Fig. 9). Conclusions In this paper, an MWIR continuous zoom optical system with a large zoom ratio and long focal length is designed. The secondary imaging, positive group mechanical compensation, and smooth root replacement are used, and a warm shield by switching the rear group of the zoom lens is introduced to change F- Number of the optical system at a long focal length. The optical path is ingeniously folded by two mirrors, which realizes the compact and miniaturization design of the MWIR continuous zoom system with a focal length from 25 mm to 1200 mm. The MWIR continuous zoom lens has excellent imaging quality within the operating temperature range of − 40-60 ℃. The optical diameter of the front group is 230 mm, and the overall length after folding is only 350 mm. The overall size of the zoom thermal imager based on this optical system is less than 360 mm (L)×238 mm (W)×290 mm (H). This compact MWIR zoom optical system has many advantages, such as a compact structure, large zoom ratio, long focal length, high resolution, and good imaging quality, which can be used in the new generation of high- performance photoelectric pods. © 2023 Chinese Optical Society. All rights reserved.
  Accession Number: 20232914413238
• Record 375 of
  
  Title:Design of optical system for wide-spectrum visible-short wave infrared imaging
  
  Author(s):Xuan, Bin(1); Zhao, Zeyu(2); Luo, Yaowei(3); Wei, Qun(3); Zhu, Yixian(1); Wang, Yajun(4)
  Source: Hongwai yu Jiguang Gongcheng/Infrared and Laser Engineering  Volume: 52  Issue: 4  Article Number: 20220638  DOI: 10.3788/IRLA20220638  Published: April 2023  
  Abstract:Objective The industrial lens for machine vision inspection needs not only to meet the design requirements of lightweight and large field of view, but also have high luminous flux. In this paper, based on the needs of machine vision engineering applications, an optical system for wide-spectrum visible-short wave infrared imaging is designed using the optical design software ZEMAX. The Wide spectrum visible-short wave infrared imaging system can operate in the band of 0.4-1.7 μm. The system is composed of 7 groups of 10 lenses. The MTF value is greater than 0.4 at the Nyquist frequency of 100 lp/mm. The F number of the system is 2.8, and the distortion is less than 1.4%. All kinds of aberrations have been well corrected and balanced. And the system has good imaging performance. It has certain reference value for the design of similar optical systems. Methods The optical system structures are usually divided into refractive system, reflective system and hybrid system. Different optical system structures have their own advantages and disadvantages. According to the imaging performance of the system and the cost-performance ratio in industrial applications, the refractive system can meet the requirements of large field of view, low distortion and compact structure. The refractive system is used to observe through refraction of transmitted light, so it is widely used in optical structure selection. At the time, by using the conventional processing and adjustment methods, it can meet the accuracy requirements. It has the characteristics of stable image quality, small stray light and high element transmittance. Results and Discussions According to the actual needs of industrial testing, the main parameters to be considered in the structural design of the wide-spectrum visible-short wave infrared imaging optical system are lens material, working band, focal length, F number, field angle, total length of the system, etc. Based on the analysis of the parameters of the wide-band infrared imaging system, the resolution CMOS area array detector is 2 448×2 048. The pixel size is 3.45 μm. The target size is 2/3 inch (1 inch=2.54 cm), and the lens has stable optical performance and good imaging quality in the operating temperature range of 0-50 ℃. After the initial structure of the system is determined, the design structure is further optimized using subsequent repeated aberration correction. The optimized wide-spectrum visible-short wave infrared imaging optical system is composed of 7 groups of lenses, and the number of the lenses is 10. The diaphragm is located on the rear surface of the fourth lens, and the front surface of the tenth lens is aspheric. The total length of the system is 79.6 mm, the diameter of the entrance pupil is 9.9 mm, and the F-number is 2.8. It can image in the visible light and short-wave infrared bands. After testing, the point array of the system's field of view is very close to the Airy spot, which is close to the diffraction limit, and meets the imaging requirements. The maximum astigmatism and field curvature of the system is 0.1 mm, and the maximum distortion is 1.4%, which meets the requirements of the system design for field curvature and distortion. The systematic tolerance is analysed based on diffraction MTF average. According to the experience and actual technological level, firstly, relatively loose tolerance preset value of each parameter is given, and then the tolerance analysis is carried out based on the design results, finally the particularly sensitive tolerance is found out and the tolerance is reallocated. Through Monte Carlo analysis of MTF, the results show that at 100 lp/mm, the nominal value of MTF is 0.559, the best value is 0.554, the worst value is 0.333, the average value is 0.481, and the standard deviation is 0.052, the MTF of 90% of the lens≥ 0.410, the MTF of 50% of the lens ≥ 0.427, and the MTF of 10% of the lens≥ 0.540. Based on the results, the MTF can meet the technical index requirements under the given tolerance. In order to better prove the performance of the optical system, the bruises in the interior of agricultural products are taken with a visible light band camera and a short-wave infrared camera respectively, which proved that the bruises can be clearly seen in the object image of this wavelength by SWIR imaging. The ability of SWIR to penetrate plastic was proved by shooting through plastic bottles. The experiment proves that the system has good detection effect in industrial detection. Conclusions With the increasing demand of machine vision for composite image information, the modern optical imaging technology will expand beyond the visible and near-infrared bands. Short-wave infrared will be more widely used in the future because of its resolution comparable to visible light and unique optical performance. © 2023 Chinese Society of Astronautics. All rights reserved.
  Accession Number: 20232614325902
• Record 376 of
  
  Title:Free-form surface reconstruction of off-axis three mirror optical system based on Rhino
  
  Author(s):Chang, Lingying(1); Chen, Kui(1); Zhao, Yuhang(1); Qiu, Yuehong(2); Wang, Guanru(1); Wang, Xinyou(1)
  Source: Proceedings of SPIE - The International Society for Optical Engineering  Volume: 12565  Issue: null  Article Number: 125653S  DOI: 10.1117/12.2663242  Published: 2023  
  Abstract:With the development of modern space optical system, off-axis reflective system with wide spectrum, high resolution and large field of view has become the main direction of optical design. However, the off-axis property of off-axis reflective structure brings asymmetric aberration, which makes designers use free-form surface frequently to correct the aberration of optical system and improve the imaging quality. When the Trace Pro optical mechanical simulation software cannot accurately convert the optical system with free-form surface in CODE V, it is difficult to simulation stray light and analysis environmental in the subsequent studies. The reconstruction of free-form surface of off-axis three mirror optical systems are realized by Rhino in this paper. For the free-form surface in the off-axis three mirror optical systems designed by CODE V, a uniform circular dot ring array sampling method based on polar coordinates is proposed to obtain the free-form surface point cloud data. The point deviation of 5mm-80mm was analyzed, and the optimal sampling interval for the point cloud data of XY polynomial free-form surface with an aperture of 150mm was determined to be 10mm; The NURBS method is used to reconstruct the free-form surface model in Rhino, and the free-form surface reconstruction of the off-axis three mirror optical system is modeled in Trace Pro. Through the simulation of imaging optical path and the analysis of image point dispersion spot radius, it is verified that the free-form surface model of off-axis three mirror optical system can be reconstructed based on rhino. This research provides an effective method reference for optical mechanical joint simulation analysis. © 2023 SPIE.
  Accession Number: 20232114127038
• Record 377 of
  
  Title:Study on the influence of spectral overflow and its correction method of push broom static hadamard transform spectral imager
  
  Author(s):Zhou, Yingshu(1,2); Gao, Xiaohui(1); Liu, Jie(1); Liu, Xuebin(1)
  Source: Proceedings of SPIE - The International Society for Optical Engineering  Volume: 12558  Issue: null  Article Number: 1255807  DOI: 10.1117/12.2647236  Published: 2023  
  Abstract:Hadamard transform spectral imaging technology has high signal-To-noise ratio and the advantage in energy distribution. In recent decades, related works focus on dynamic coding Hadamard spectral imager instead of static coding ones. The latter has great potential value in spaceborne and airborne applications, but the accuracy of its restored spectral image data is poor at present. Therefore, it is necessary to further study the formation mechanism and correction method of errors in static coding Hadamard spectral imager. In this paper, the influencing mechanism and correction method of spectral overflow are studied. Firstly, the imaging and restoration process of the Hadamard coding spectral imager with spectral overflow is mathematically deduced, and the conclusion is compared with the simulated restoration results. Secondly, the simulated results are compared with the experimental data, verifying that spectral overflow is an important source of the error in experimental results. Finally, a correction method for eliminating spectral overflow errors under certain conditions is proposed, and the effectiveness of the method is verified by simulation. This paper can provide reference for the design and data restoration of static coding Hadamard spectral imager. © COPYRIGHT SPIE. Downloading of the abstract is permitted for personal use only.
  Accession Number: 20230713574415
• Record 378 of
  
  Title:Push-broom compressive hyperspectral imaging method based on self-fusion refinement
  
  Author(s):Zhu, Mengjun(1); Yi, Wenjun(1); Du, Junyi(2); Zhu, Shuyue(1); Qi, Junli(1); Fu, Meicheng(1); Li, Libo(3); Li, Xiujian(1)
  Source: Optics Communications  Volume: 530  Issue: null  Article Number: 129198  DOI: 10.1016/j.optcom.2022.129198  Published: March 1, 2023  
  Abstract:Compressive hyperspectral imaging (CHI) with random encoding mask usually suffers from various noises and artifacts. Inspired by the dual-camera CHI techniques based on hyperspectral (HS) and multispectral (MS) image fusion, herein, we present a single-camera push-broom CHI method based on self-fusion refinement (SFR). In this work, the MS guidance image for data fusion is derived directly from the raw solved HS data cube itself rather than any additional data source, which turns cross-fusion into self-fusion; furthermore, a modified joint bilateral filtering (JBF) fusion algorithm is developed to adapt this self-fusion problem, and an adaptive range Gaussian radius is adopted to avoid the invalidation or over-smoothing effects so as to ensure spatial and spectral improvement. The visualized and quantitative assessment results both demonstrate that the proposed method achieves high-quality HS imaging in terms of noise and artifact removal and spatial–spectral fidelity. Furthermore, the proposed method has a great flexibility and extensibility, whose performances highly depend on the exact fusion algorithm adopted, and a more suitable fusion algorithm will lead to better reconstruction quality; herein, the SFR process by the modified JBF achieves better performances than SFR by guided filtering (GF) or Markov random field (MRF). © 2022 Elsevier B.V.
  Accession Number: 20225213290363
• Record 379 of
  
  Title:Research on assembly method of non-coaxial transmissive optical system
  
  Author(s):LeiYu(1,2); Ma, Caiwen(1); Kang, Shifa(1); Yin, Yamei(1); Cao, Mingqiang(1)
  Source: Proceedings of SPIE - The International Society for Optical Engineering  Volume: 12507  Issue: null  Article Number: 125071C  DOI: 10.1117/12.2655612  Published: 2023  
  Abstract:Coaxial transmission optical systems can be assembled by optical centering processing and optical centering assembly to eliminate the eccentricity and tilt of each lens, thus ensuring the coaxiality of the lens. Non-coaxial transmission optical systems cannot be assembled by the traditional optical centering method, and this type of system poses a new challenge to the assembly method. Aiming at a non-coaxial transmissive optical system, this paper proposes a precise assembly method based on the spatial coordinate change and the principle of self-collimation imaging. Firstly, we calculate the spatial angle and eccentricity value of different axis mirror groups, and then use two self-collimating theodolites and optical reticle centering tools to construct the spatial angle reference and eccentricity reference for different axis mirror groups. Then, the spatial position of each lens group is determined by the adjustment method of auto-collimation. The article finally carried out the alignment experiment. The wavefront RMS of the optical system after alignment is 0.026λ@632.8nm which meets the design requirements and verifies the effectiveness of the proposed method. © 2023 SPIE.
  Accession Number: 20230613537948
• Record 380 of
  
  Title:Guide to the design of broadband full polarization imager based on dispersion-compensation Savart plates
  
  Author(s):Zhang, Ning(1); Zhao, Mingfan(1,2); Zhang, Yunyao(3); Li, Siyuan(1)
  Source: Applied Optics  Volume: 62  Issue: 19  Article Number: null  DOI: 10.1364/AO.488427  Published: July 2023  
  Abstract:We provide a broadband channeled, modulated full polarization imaging technology based on dispersioncompensation Savart plates in 2020. It has the advantages of being compact, using the snapshot method, and having a bandwidth of 0.132 _m. It is thus invaluable for applications in diverse fields, including remote sensing, biomedicine, and military science. However, there are a lot of angle restrictions in the system. In practice, these angles cannot achieve such high machining precision, and we use the tolerance or compensation method of errors to analyze the influence of the angle deviation. This analysis will help the system achieve better compactness and stability and provide analysis methods for systems that use crystals as its key elements. © 2023 Optica Publishing Group.
  Accession Number: 20232814388068
• Record 381 of
  
  Title:Computer-Aided alignment method for a four-mirror off-Axis reflective optical system
  
  Author(s):Lei, Yu(1,2); Ma, Caiwen(1); Shi, Yuanyuan(1); Hou, Xiaohua(1)
  Source: Proceedings of SPIE - The International Society for Optical Engineering  Volume: 12976  Issue: null  Article Number: 1297622  DOI: 10.1117/12.3009608  Published: 2023  
  Abstract:Off-Axis optical systems do not have rotational symmetry and cannot be optically centering turned by CNC machine to eliminate component tilt errors, so they are more difficult to be aligned than the coaxial optical systems. In this paper, the computer-Aided alignment technology is carried out for a four-mirror off-Axis reflective optical system. Firstly, aberration characteristic analysis is performed to obtain the relationship between the degrees of freedom for mirrors and the wavefront coefficients. Using the results of the above analysis, a segmental alignment method is proposed. Finally, the article has completed the experimental verification for the optical system alignment. The wavefront quality meets the requirement which verifies the validity of the theoretical analysis. The research results can provide effective solutions for the alignment of various off-Axis optical systems. © COPYRIGHT SPIE. Downloading of the abstract is permitted for personal use only.
  Accession Number: 20240315401971
• Record 382 of
  
  Title:Research on Rocket Engine Pose Measurement Technology Based on Monocular Vision
  
  Author(s):Zhang, Haifeng(1,2,3); Wu, Jiaxin(2,4); Liu, Delian(1); Duan, Jiaxin(2,5); Guo, Gao(1,2); Zhang, Gaopeng(2,3); Ren, Long(2,3); Cao, Jianzhong(2,3); Mei, Chao(2,3)
  Source: Proceedings of SPIE - The International Society for Optical Engineering  Volume: 12934  Issue: null  Article Number: 129340I  DOI: 10.1117/12.3008182  Published: 2023  
  Abstract:In recent years, in the aerospace field, higher requirements have been put forward for the position and pose measurement tasks such as engines. Computer vision technology is the key technology to achieve the target measurement tasks. Rocket engine pose measurement provides technical support for engine pose control strategy optimization. Based on the principle of monocular vision, this article designs a measurement system with strong stability and high accuracy for launch vehicle engines, and verifies the effectiveness of the measurement system through two sets of simulation experiments. In terms of image preprocessing, the noise reduction effects of spatial filtering and wavelet transform were compared, and a preprocessing method combining wavelet transform and image enhancement was designed; In terms of feature extraction, improvements have been made to the traditional Accelerated Feature Segmentation Test (FAST) algorithm to reduce the impact of lighting on feature point extraction under different postures, while retaining the advantage of high-precision measurement algorithms under point features; In terms of pose measurement, the centroid and translation vector pre pose iterative optimization algorithm is adopted, which greatly reduces the computational complexity in the pose calculation iteration process and improves the speed of spatial target pose calculation. © 2023 SPIE.
  Accession Number: 20234815136208
• Record 383 of
  
  Title:Proportional fairness secrecy beamforming for massive MIMO-SWIPT systems with low-resolution ADCs
  
  Author(s):Li, Hao(1); Cao, Jiawei(1); Li, Qi(1); Zhang, Shengyi(1); Zhao, Yijiu(1); Wang, Zhigang(1); Meng, Jiacheng(2,3); Wang, Houjun(1)
  Source: Digital Signal Processing: A Review Journal  Volume: 136  Issue: null  Article Number: 103943  DOI: 10.1016/j.dsp.2023.103943  Published: May 2023  
  Abstract:Simultaneous wireless information and power transfer (SWIPT) technology is one of the solutions to the energy shortage problem in Massive multiple-input and multiple-output (MIMO) systems, while the low-resolution analog-to-digital convertor (ADC) is a potential way to significantly reduce the power consumption of radio frequency circuits in Massive MIMO enabled SWIPT systems. In this paper, we focus on the secrecy transmission maximization problem for Massive MIMO-SWIPT systems over Nakagami-m fading channels, where a low-resolution ADC quantization model and a non-linear energy harvester are exploited. By considering proportional fairness, a joint beamforming design and power allocation problem are proposed to achieve the sum logarithmic secrecy rates. To tackle the non-convex maximization problem, the suboptimal solutions of the beamforming design and power allocation are respectively obtained based on a successive convex approximation and a semidefinite relaxation. Numerical results demonstrate the effectiveness of the proposed joint optimization scheme. © 2023
  Accession Number: 20231013667052
• Record 384 of
  
  Title:Multifunctional all-fiber polarization-maintaining nonlinear pulse amplifier
  
  Author(s):Nie, Liang(1); Shi, Zhaojiang(2); Chen, Zeyou(3); Wang, Wei(1); Gao, Ge(1); Xu, Yusheng(1); Li, Xiaohui(1,2); Fan, Wenhui(3)
  Source: Optik  Volume: 281  Issue: null  Article Number: 170796  DOI: 10.1016/j.ijleo.2023.170796  Published: June 2023  
  Abstract:A multifunctional all-fiber polarization-maintaining nonlinear amplifier system is proposed and investigated. Two Erbium-doped polarization-preserving gain fibers are used to amplify the seed laser and split into four output points with different transmission fibers to obtain four stable ultra-short pulses with different durations, which vary from tens of fs to ps level. And the output powers are tens of mW and can be changed with different output point. The seed laser in this process has a repetition rate of 113 MHz, a pulse duration of about 450fs, and different absorption coefficients for the two gain fibers. It is demonstrated that the proposed fiber laser with varied pulse duration can be potentially applied in laser detection, terahertz generation, and even different types of material processing. © 2023
  Accession Number: 20231413853673