Optical-mechanical system design of SAR real-time imaging optical processor

Zhao Hongqiang; Zhang Xingxiang; Wang Duo; Bi Guoling; Fu Tianjiao

doi:10.12086/oee.2022.210421

Article navigation > Opto-Electronic Engineering > 2022 Vol. 49 > No. 9 > 210421

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Zhao H Q, Zhang X X, Wang D, et al. Optical-mechanical system design of SAR real-time imaging optical processor[J]. Opto-Electron Eng, 2022, 49(9): 210421. doi: 10.12086/oee.2022.210421

Citation:

Zhao H Q, Zhang X X, Wang D, et al. Optical-mechanical system design of SAR real-time imaging optical processor[J]. Opto-Electron Eng, 2022, 49(9): 210421. doi: 10.12086/oee.2022.210421

Optical-mechanical system design of SAR real-time imaging optical processor

1.
Changchun Institute of Optics, Fine Mechanics and Physics, Chinese Academy of Sciences, Changchun, Jilin 130033, China
2.
University of Chinese Academy of Sciences, Beijing 100049, China

Fund Project: National Natural Science Foundation of China (61801455)

More Information

^*Corresponding author: jan_zxx@163.com

Received Date 04 January 2022

Revised Date 14 April 2022

Published Date 25 September 2022

Abstract

Abstract

In order to further improve the real-time imaging processing ability of synthetic aperture radar (SAR) in the face of massive echo data, the optical and mechanical system of SAR real-time imaging optical processor is designed and analyzed based on 4f optical structure. Firstly, a Fourier transform lens with an entrance pupil diameter of 21 mm, a field angle of 7°, and a focal length of 172 mm is designed for the filtering algorithm, and a compact design is adopted for the 4f optical system. Then, the flexible mirror base in 4f optical mechanical structure is optimized by using the integrated optimization method, and the overall structure is modularized designed and analyzed. The results show that the imaging quality of 4f optical system tends to the diffraction limit, and the MTF of Fourier transform lens is better than 0.57 at 55 lp/mm. The RMS value of lens surface shape of 4f optical mechanical system under normal temperature 1g gravity condition is less than λ/50. The fundamental frequency of the overall structure is greater than 100 Hz. The overall size of 4f optical processor is 405 mm×145 mm×92 mm, the mass is about 2.94 kg, and its volume and mass are only 30% and 48% of those of oblique plane optical processors with the same SAR data processing level. Through data simulation, it shows that the system design meets the needs of real-time imaging on satellite or airborne.
- synthetic aperture radar /
- real-time imaging processing /
- compact design /
- modular design

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References

[1]	Gini F. Grand challenges in radar signal processing[J]. Front Sign Process, 2021, 1: 664232. doi: 10.3389/frsip.2021.664232 CrossRef Google Scholar
[2]	Bhamidipati S R M, Srivatsa C, Gowda C K S, et al. Generation of SAR images using deep learning[J]. SN Comput Sci, 2020, 1(6): 355. doi: 10.1007/s42979-020-00364-z CrossRef Google Scholar
[3]	Liu F, Huang P P, Tan W X, et al. Portable Omni-directional micro deformation monitoring radar system[C]//2020 IEEE MTT-S International Microwave Workshop Series on Advanced Materials and Processes for RF and THz Applications (IMWS-AMP). Suzhou: IEEE, 2020: 1–3. Google Scholar
[4]	Kulkarni S C, Rege P P. Pixel level fusion techniques for SAR and optical images: a review[J]. Inf Fusion, 2020, 59: 13−29. doi: 10.1016/j.inffus.2020.01.003 CrossRef Google Scholar
[5]	Marchese L, Doucet M, Harnisch B, et al. A real-time high-resolution optical SAR processor[J]. Proc SPIE, 2010, 7669: 76690M. doi: 10.1117/12.850734 CrossRef Google Scholar
[6]	Marchese L, Bourqui P, Turgeon S, et al. Extended capability overview of real-time optronic SAR processing[J]. IET Int Conf Radar Syst, 2012, 8(11): 5052−5067. doi: 10.1049/CP.2012.1608 CrossRef Google Scholar
[7]	Jin Y R, Guo R, Gao Y S, et al. A tiling of multi-SLM is used in full resolution optical SAR data processor[C]//2014 IEEE Geoscience and Remote Sensing Symposium. Quebec City, QC, Canada: IEEE, 2014: 588–591. Google Scholar
[8]	Zhang J, Gao Y S, Wang K Z, et al. An optical SAR data processor based on DMD[C]//2016 Progress in Electromagnetic Research Symposium (PIERS). Shanghai: IEEE, 2016: 2893–2897. Google Scholar
[9]	蔡志鹏, 张星祥, 陈哲, 等. 新型SAR实时成像光学系统设计[J]. 液晶与显示, 2020, 35(11): 1185−1194. doi: 10.37188/YJYXS20203511.1185 CrossRef Google Scholar Cai Z P, Zhang X X, Chen Z, et al. New SAR real-time imaging optical system design[J]. Chin J Liquid Cryst Displays, 2020, 35(11): 1185−1194. doi: 10.37188/YJYXS20203511.1185 CrossRef Google Scholar
[10]	Wang D, Ouyang R, Wang K Z, et al. Optical SAR data processing configuration with simultaneous azimuth and range matching filtering[J]. Appl Opt, 2020, 59(33): 10441−10450. doi: 10.1364/AO.409825 CrossRef Google Scholar
[11]	游明俊. 傅里叶光学[M]. 2版. 北京: 兵器工业出版社, 2000. Google Scholar You M J. Fourier Optics[M]. 2nd ed. Beijing: Ordnance Industry Press, 2000. Google Scholar
[12]	刘洪顺, 王喆, 胡琪, 等. 基于空间光调制器的层析成像技术[J]. 中国光学, 2019, 12(6): 1338−1347. doi: 10.3788/co.20191206.1338 CrossRef Google Scholar Liu H S, Wang Z, Hu Q, et al. Tomography technology based on spatial light modulator[J]. Chin Opt, 2019, 12(6): 1338−1347. doi: 10.3788/co.20191206.1338 CrossRef Google Scholar
[13]	魏加立, 曲慧东, 王永宪, 等. 空间TOF相机大视场光学镜头结构优化设计[J]. 仪器仪表学报, 2020, 41(10): 121−128. doi: 10.19650/j.cnki.cjsi.J2006719 CrossRef Google Scholar Wei J L, Qu H D, Wang Y X, et al. Structure optimization design of large field of view optical lens for the space TOF camera[J]. Chin J Sci Instr, 2020, 41(10): 121−128. doi: 10.19650/j.cnki.cjsi.J2006719 CrossRef Google Scholar
[14]	杨云良. 低温红外镜头柔性卸载结构设计与测试[D]. 廊坊: 北华航天工业学院, 2021. Google Scholar Yang Y L. Design and test of low-temperature infrared lens flexible unloading structure[D]. Langfang: North China Institute of Aerospace Technology, 2021. Google Scholar
[15]	张刘, 郑潇逸, 张帆, 等. 大容差多柔性透镜组结构优化设计[J]. 吉林大学学报(工学版), 2021, 51(2): 478−485. doi: 10.13229/j.cnki.jdxbgxb20200053 CrossRef Google Scholar Zhang L, Zheng X Y, Zhang F, et al. Structural optimization design of large tolerance and multi-flexibility lens subassembly[J]. J Jilin Univ (Eng Technol Ed), 2021, 51(2): 478−485. doi: 10.13229/j.cnki.jdxbgxb20200053 CrossRef Google Scholar
[16]	李路, 邢昆明, 赵明. 星载激光雷达望远镜主镜超轻量化结构设计[J]. 洛阳理工学院学报(自然科学版), 2021, 31(3): 73−79. doi: 10.3969/j.issn.1674-5043.2021.03.001 CrossRef Google Scholar Li L, Xing K M, Zhao M. Ultra-lightweight structure design of primary mirror of receiving telescope of space-borne Lidar[J]. J Luoyang Inst Sci Technol (Nat Sci Ed), 2021, 31(3): 73−79. doi: 10.3969/j.issn.1674-5043.2021.03.001 CrossRef Google Scholar

Overview

Overview

This paper is devoted to the research of synthetic aperture radar (SAR) real-time imaging processor. As the number of SAR imaging channels increases, the number of SAR imaging channels also presents new challenges. The optical processor not only has strong parallel processing ability, but also has the advantages of low power consumption, small volume, fast processing speed and programmability. Therefore, this paper designs and analyzes the SAR real-time imaging optical processor from the perspective of optical mechanical system design. Firstly, the system scheme principle of optical processor based on 4f optical structure is proposed, and the filtering algorithm is described in detail according to the principle. Secondly, according to the algorithm requirements, the relevant Fourier transform lens design is completed, and the compactness of 4f optical system is further strengthened. Then, the flexible design of the lens base is carried out, and the optimal parameter model is found by using the integrated optimization method. At the same time, it meets the modular design idea, completes the corresponding optical mechanical structure design, and obtains the optical mechanical system model of the overall scheme. The specific design results obtained based on the above research methods are as follows: in the optical design process, a Fourier transform lens with an entry pupil diameter of 21 mm, a field angle of 7°, and a focal length of 172 mm is obtained, and its MTF is better than 0.57 at 55 lp/mm. And the 4f optical system whose imaging quality tends to the diffraction limit meets the Rayleigh criterion. In the process of optical mechanical structure design, the overall size of 4f optical mechanical system is 405 mm×145 mm× 92 mm, with a mass of about 2.94 kg, and its volume and mass are only 30% and 48% of that of the inclined plane optical processor with the same SAR data processing level; At the same time, the RMS value of lens surface under normal temperature 1g gravity condition is less than λ/50(λ= 532 nm), the fundamental frequency of the overall structure is greater than 100 Hz, which can fully meet the expected design goal of the processor optical mechanical system. Finally, the simulation processing of SAR data is carried out on the optical platform. According to the simulation results, it shows that the system can be suitable for airborne or spaceborne real-time processing scenes. To sum up, the 4f optical processor designed in this paper can provide a certain reference value for improving the real-time imaging processing ability of SAR.