Ningning Shi, Shengtong Wang, Gaopeng Xue, Mengfang Liu, Yaodong Han, Junhao Zhu, K. Ni, Qian Zhou, Xiaohao Wang, Xinghui Li
Six-degree-of-freedom (6-DOF) grating encoders have a wide prospect of application. Aiming at the requirement of realtime detection of 6-DOF grating encoders, this study designs and builds a real-time calculation system platform based on field-programmable gate array (FPGA). We realized a real-time parallel calculation of 16-path displacement signal and 24path angular displacement signal, respectively. Specifically, the optical interference signals, generated by the translation and rotation of the motion stages, are firstly shaped by the front-end analog circuit. We further sampled the front-end analog circuit into an FPGA through an analog-to-digital convertor (ADC) for the realization of the digital filtering, amplitude normalization, phase correction, and phase-information calculation. Thus, the calculated signals on the 6-DOF motions can be displayed in real time. The established system was evaluated with the experimental parameters in terms of the translation with a 50 μm/s moving speed and an 18 mm stroke and the rotation with a frequency of 0.5 Hz, a step length of 100 micro-rad, and within a reciprocating rotation of 24 s. Finally, a linear-displacement error of <1 nm and an angle displacement error of <0.9 micro-rad were achieved, respectively. Furthermore, the system delay of <15 ms is obtained, exhibiting a high performance for the real-time measurement and high integration in the practical application.
{"title":"A real-time processing system for dual-channel six-degree-of-freedom grating ruler based on FPGA","authors":"Ningning Shi, Shengtong Wang, Gaopeng Xue, Mengfang Liu, Yaodong Han, Junhao Zhu, K. Ni, Qian Zhou, Xiaohao Wang, Xinghui Li","doi":"10.1117/12.2602239","DOIUrl":"https://doi.org/10.1117/12.2602239","url":null,"abstract":"Six-degree-of-freedom (6-DOF) grating encoders have a wide prospect of application. Aiming at the requirement of realtime detection of 6-DOF grating encoders, this study designs and builds a real-time calculation system platform based on field-programmable gate array (FPGA). We realized a real-time parallel calculation of 16-path displacement signal and 24path angular displacement signal, respectively. Specifically, the optical interference signals, generated by the translation and rotation of the motion stages, are firstly shaped by the front-end analog circuit. We further sampled the front-end analog circuit into an FPGA through an analog-to-digital convertor (ADC) for the realization of the digital filtering, amplitude normalization, phase correction, and phase-information calculation. Thus, the calculated signals on the 6-DOF motions can be displayed in real time. The established system was evaluated with the experimental parameters in terms of the translation with a 50 μm/s moving speed and an 18 mm stroke and the rotation with a frequency of 0.5 Hz, a step length of 100 micro-rad, and within a reciprocating rotation of 24 s. Finally, a linear-displacement error of <1 nm and an angle displacement error of <0.9 micro-rad were achieved, respectively. Furthermore, the system delay of <15 ms is obtained, exhibiting a high performance for the real-time measurement and high integration in the practical application.","PeriodicalId":308574,"journal":{"name":"Optical Design and Testing XI","volume":"28 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2021-10-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"131476416","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Nowadays, large aperture space-borne optical camera is one important payload used to capture optical images of space targets based on satellite platform, but many factors could prevent space-borne camera from obtaining satisfactory images. Firstly, vibration during launch, moisture absorption, deflation and violent temperature variation and so on could make the focal plane of space-borne camera deviate from its ideal position. Secondly, space targets are usually distant, moving quite fast and especially noncooperative targets may even appear in unknown distances. In this case, frequent, rapid and precise on-orbit focusing mechanism are indispensable to traditional imaging system, but wave-front coded imaging provides another choice. In wave-front coded imaging system, by introducing a suitably designed phase mask, the optical transfer function will become insensitive to defocus and the clear images similar to diffraction limited ones could be obtained through digital restoration. Therefore in this manuscript, the experimental research is carried out to investigate the effectiveness of wave-front coding technique in realizing high-resolution imaging without introducing any focusing mechanisms. By only adding a cubic phase mask to the exit pupil with diameter of approximately 80mm and keeping other optical-mechanical structures of a prototype large aperture camera with focal length of 6000mm and aperture of 600mm unchanged, the extension of depth of focus could be obtained. In the collimator based testing, the depth of focus of that prototype space-borne camera could be extended 8.5x approximately, which provides another way to realize high-resolution imaging of space targets while designing space-borne optical camera in future.
{"title":"Experimental research on wave-front coded imaging technique applied to large aperture space-borne optical camera","authors":"Hui Zhao, J. Mi, Chuang Li, Gangyi Zou, XueWu Fan, Jingxuan Wei","doi":"10.1117/12.2601224","DOIUrl":"https://doi.org/10.1117/12.2601224","url":null,"abstract":"Nowadays, large aperture space-borne optical camera is one important payload used to capture optical images of space targets based on satellite platform, but many factors could prevent space-borne camera from obtaining satisfactory images. Firstly, vibration during launch, moisture absorption, deflation and violent temperature variation and so on could make the focal plane of space-borne camera deviate from its ideal position. Secondly, space targets are usually distant, moving quite fast and especially noncooperative targets may even appear in unknown distances. In this case, frequent, rapid and precise on-orbit focusing mechanism are indispensable to traditional imaging system, but wave-front coded imaging provides another choice. In wave-front coded imaging system, by introducing a suitably designed phase mask, the optical transfer function will become insensitive to defocus and the clear images similar to diffraction limited ones could be obtained through digital restoration. Therefore in this manuscript, the experimental research is carried out to investigate the effectiveness of wave-front coding technique in realizing high-resolution imaging without introducing any focusing mechanisms. By only adding a cubic phase mask to the exit pupil with diameter of approximately 80mm and keeping other optical-mechanical structures of a prototype large aperture camera with focal length of 6000mm and aperture of 600mm unchanged, the extension of depth of focus could be obtained. In the collimator based testing, the depth of focus of that prototype space-borne camera could be extended 8.5x approximately, which provides another way to realize high-resolution imaging of space targets while designing space-borne optical camera in future.","PeriodicalId":308574,"journal":{"name":"Optical Design and Testing XI","volume":"86 2 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2021-10-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"130887129","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
When the spatial visible light camera images the detection target, non-imaged light in the space also reaches the imaging surface through the lens, forming an image on the detector. Some of the light is imaged on the image surface after multiple reflections inside the lens. These non-target images affect the image quality of the camera. In severe cases, the camera may not work properly. In order to reduce the influence of stray light on the imaging system and improve the imaging performance of the camera, firstly, the generation mechanism of stray light in the visible light system is analyzed, and the stray light suppression measures are proposed. Secondly, the system is then analyzed using ZEMAX software. The optical system design of the camera with the previous stray light problem was improved, and the stray light modeling analysis was performed on the improved result, and finally the space reconnaissance camera that satisfies the use requirements was obtained.
{"title":"Stray light analysis and optical design improvement of visible light detection camera on space platform","authors":"Yu Zhang, Huiping Zhang, Fang Han, Haiyang Ding, Jiyang Shang","doi":"10.1117/12.2602735","DOIUrl":"https://doi.org/10.1117/12.2602735","url":null,"abstract":"When the spatial visible light camera images the detection target, non-imaged light in the space also reaches the imaging surface through the lens, forming an image on the detector. Some of the light is imaged on the image surface after multiple reflections inside the lens. These non-target images affect the image quality of the camera. In severe cases, the camera may not work properly. In order to reduce the influence of stray light on the imaging system and improve the imaging performance of the camera, firstly, the generation mechanism of stray light in the visible light system is analyzed, and the stray light suppression measures are proposed. Secondly, the system is then analyzed using ZEMAX software. The optical system design of the camera with the previous stray light problem was improved, and the stray light modeling analysis was performed on the improved result, and finally the space reconnaissance camera that satisfies the use requirements was obtained.","PeriodicalId":308574,"journal":{"name":"Optical Design and Testing XI","volume":"14 4","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2021-10-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"132192994","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
V. Korolkov, R. K. Nasyrov, V. Khomutov, D. A. Belousov, R. Kuts
Conformal correctors for high-power solid-state YAG: Nd3 + lasers are used for compensation of density variations inside active media. These correctors decrease laser beam aberrations and allows better focusing of laser light. Fabrication was done by direct laser writing on photoresist. Method of specular spectrometric reflectometry to control the shape of correctors at the stage of relief in a photoresist is considered. The combination of the methods used significantly increases the productivity of the production of correctors, combined with a reduction in the cost of the process.
{"title":"Development of methods for the formation and control of a given distribution of the photoresist thickness for conformal correctors fabrication","authors":"V. Korolkov, R. K. Nasyrov, V. Khomutov, D. A. Belousov, R. Kuts","doi":"10.1117/12.2604808","DOIUrl":"https://doi.org/10.1117/12.2604808","url":null,"abstract":"Conformal correctors for high-power solid-state YAG: Nd3 + lasers are used for compensation of density variations inside active media. These correctors decrease laser beam aberrations and allows better focusing of laser light. Fabrication was done by direct laser writing on photoresist. Method of specular spectrometric reflectometry to control the shape of correctors at the stage of relief in a photoresist is considered. The combination of the methods used significantly increases the productivity of the production of correctors, combined with a reduction in the cost of the process.","PeriodicalId":308574,"journal":{"name":"Optical Design and Testing XI","volume":"71 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2021-10-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"124850320","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
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