Sea surface temperature (SST) is a key parameter for monitoring the ocean environment and understanding various ocean phenomena, and is a key indicator of climate change. Satellite remote sensing data is an important technical tool for SST research, but the availability of data is reduced due to the influence of clouds and aerosols, which generate a large amount of missing data. The data interpolation empirical orthogonal function (DINEOF) method has usability and accuracy in reconstructing missing grid points of remote sensing datasets. In this study, we use a convolutional self-encoder neural network, modified for model skip connection and fully connected layers, and introduce an attention mechanism to extract spatio-temporal features of SST data, called attention data interpolation convolutional autoencoder (A-DINCAE), to achieve the reconstruction of infrared radiometer SST data and compare A-DINCAE with DINCAE and DINEOF Reconstruction accuracy. The accuracy of the reconstruction results is quantitatively evaluated using cross-validation datasets and actual measurement data, and the study area is selected as the South China Sea with the boundaries of 103-121°E and 0-23°N. The validation results show that the reconstruction effect of the A-DINCAE model on the SST missing data is better than that of DINCAE, the accuracy of the reconstruction results is much higher than that of DINEOF, and the reconstruction results restore the main SST of the sea area physical features of the sea area. This paper confirms that the attention mechanism can improve the DINCAE spatio-temporal feature extraction ability, and the small-scale features of the missing data are restored under the same data reconstruction conditions, and the A-DINCAE is more efficient than DINEOF, and The accuracy of the improved model has been improved.
{"title":"Reconstruction of sea surface temperature data from sea satellite observation based on convolutional automatic encoder","authors":"Yuheng Li, Kaixiang Cao, Yuxi Li, Weifu Sun","doi":"10.1117/12.2664741","DOIUrl":"https://doi.org/10.1117/12.2664741","url":null,"abstract":"Sea surface temperature (SST) is a key parameter for monitoring the ocean environment and understanding various ocean phenomena, and is a key indicator of climate change. Satellite remote sensing data is an important technical tool for SST research, but the availability of data is reduced due to the influence of clouds and aerosols, which generate a large amount of missing data. The data interpolation empirical orthogonal function (DINEOF) method has usability and accuracy in reconstructing missing grid points of remote sensing datasets. In this study, we use a convolutional self-encoder neural network, modified for model skip connection and fully connected layers, and introduce an attention mechanism to extract spatio-temporal features of SST data, called attention data interpolation convolutional autoencoder (A-DINCAE), to achieve the reconstruction of infrared radiometer SST data and compare A-DINCAE with DINCAE and DINEOF Reconstruction accuracy. The accuracy of the reconstruction results is quantitatively evaluated using cross-validation datasets and actual measurement data, and the study area is selected as the South China Sea with the boundaries of 103-121°E and 0-23°N. The validation results show that the reconstruction effect of the A-DINCAE model on the SST missing data is better than that of DINCAE, the accuracy of the reconstruction results is much higher than that of DINEOF, and the reconstruction results restore the main SST of the sea area physical features of the sea area. This paper confirms that the attention mechanism can improve the DINCAE spatio-temporal feature extraction ability, and the small-scale features of the missing data are restored under the same data reconstruction conditions, and the A-DINCAE is more efficient than DINEOF, and The accuracy of the improved model has been improved.","PeriodicalId":258680,"journal":{"name":"Earth and Space From Infrared to Terahertz (ESIT 2022)","volume":"8 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2023-01-31","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"125520105","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}
The successive launches of hyperspectral satellites have provided a rich data source for soil quality monitoring. Soil Organic Matter (SOM) is an essential soil quality indicator. How to use multi-source hyperspectral data for cooperative monitoring to obtain SOM content is an important issue in black soil surveys. In this paper, a spectral index of SOM applicable to collaborative monitoring with multi-source hyperspectral data is developed for the black soil region. First, a series of spectral indices were constructed by combining spectral transformations (such as reciprocal and square root) and dual-band index formulas (such as ratio and difference), respectively. Then, the Pearson’s correlation coefficient (ρ) of SOM and all the spectral indices were calculated for each dataset. Finally, the optimal spectral index of SOM was determined based on the ρ of different datasets. The results show that the optimal spectral index of SOM is DIOR (560,600). The R2 of the exponential fit reaches 0.54, indicating that DIOR (560,600) can effectively characterize the soil organic matter content. Also, DIOR (560,600) is stable and simple to calculate, showing great potential in SOM estimation of black soil using multi-source satellite hyperspectral data.
{"title":"Research on spectral index of soil organic matter in black soil for collaborative monitoring of multi-source hyperspectral data","authors":"K. Shang, He Gu, Ailing Qin, C. Xiao, Qiang Shen","doi":"10.1117/12.2666006","DOIUrl":"https://doi.org/10.1117/12.2666006","url":null,"abstract":"The successive launches of hyperspectral satellites have provided a rich data source for soil quality monitoring. Soil Organic Matter (SOM) is an essential soil quality indicator. How to use multi-source hyperspectral data for cooperative monitoring to obtain SOM content is an important issue in black soil surveys. In this paper, a spectral index of SOM applicable to collaborative monitoring with multi-source hyperspectral data is developed for the black soil region. First, a series of spectral indices were constructed by combining spectral transformations (such as reciprocal and square root) and dual-band index formulas (such as ratio and difference), respectively. Then, the Pearson’s correlation coefficient (ρ) of SOM and all the spectral indices were calculated for each dataset. Finally, the optimal spectral index of SOM was determined based on the ρ of different datasets. The results show that the optimal spectral index of SOM is DIOR (560,600). The R2 of the exponential fit reaches 0.54, indicating that DIOR (560,600) can effectively characterize the soil organic matter content. Also, DIOR (560,600) is stable and simple to calculate, showing great potential in SOM estimation of black soil using multi-source satellite hyperspectral data.","PeriodicalId":258680,"journal":{"name":"Earth and Space From Infrared to Terahertz (ESIT 2022)","volume":"45 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2023-01-31","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"121207731","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}
Fengyun-4A (FY-4A) is the second-generation geostationary orbit meteorological satellite series with higher observation frequency and resolution compared with the first-generation in China. While, the spatial resolution (4km) of the infrared channel and water vapor channel is lower than that of the visible light channel (1km), which limits the application of FY- 4A in extreme weather monitoring. At the same time, in order to adapt to the characteristics of the rapid time change of small and medium-scale meteorological disasters, this study based on the deep learning method to downscale the FY-4A satellite data in space and time. The approach consists of two main steps: first, FY-4A data is downscaled using a ESRGAN model transfer learning, which can extract spatially relevant information and reconstruct image resolutions such as infrared channels from 4km to 1km; second, based on the Super SloMo model, the time-related information can be extracted to effectively downscale the FY-4A data, and the temporal resolution of the FY-4A is reconstructed from 15min to 6min , making it comparable to the time resolution of weather radar. The spatial resolution evaluation based on the visible light channel shows that the method used in this study is superior to the spatial downscaling method of bicubic interpolation and Papoulis-Gerchberg in Peak Signal to Noise Ratio (PSNR), Structural Similarity (SSIM), Root Mean Square Error (RMSE), and Correlation Coefficient (CC), and can more effectively convert low-resolution FY-4A satellite data to the corresponding high-resolution satellite data. At the same time, the time-related information can be extracted based on the time downscaling model, the time resolution is converted from 15min to 6min, and the movement direction of the cloud remains the same. Compared with traditional methods, this downscaling approach is a postprocessing method of satellite data with higher precision, which can improve the application value of FY-4A in disaster weather warning.
{"title":"A space-time downscaling approach of Fengyun-4A satellite based on deep learning","authors":"Chunlei Yang, Mengzhen Xie, Mingjian Gu, Lili Liu","doi":"10.1117/12.2664546","DOIUrl":"https://doi.org/10.1117/12.2664546","url":null,"abstract":"Fengyun-4A (FY-4A) is the second-generation geostationary orbit meteorological satellite series with higher observation frequency and resolution compared with the first-generation in China. While, the spatial resolution (4km) of the infrared channel and water vapor channel is lower than that of the visible light channel (1km), which limits the application of FY- 4A in extreme weather monitoring. At the same time, in order to adapt to the characteristics of the rapid time change of small and medium-scale meteorological disasters, this study based on the deep learning method to downscale the FY-4A satellite data in space and time. The approach consists of two main steps: first, FY-4A data is downscaled using a ESRGAN model transfer learning, which can extract spatially relevant information and reconstruct image resolutions such as infrared channels from 4km to 1km; second, based on the Super SloMo model, the time-related information can be extracted to effectively downscale the FY-4A data, and the temporal resolution of the FY-4A is reconstructed from 15min to 6min , making it comparable to the time resolution of weather radar. The spatial resolution evaluation based on the visible light channel shows that the method used in this study is superior to the spatial downscaling method of bicubic interpolation and Papoulis-Gerchberg in Peak Signal to Noise Ratio (PSNR), Structural Similarity (SSIM), Root Mean Square Error (RMSE), and Correlation Coefficient (CC), and can more effectively convert low-resolution FY-4A satellite data to the corresponding high-resolution satellite data. At the same time, the time-related information can be extracted based on the time downscaling model, the time resolution is converted from 15min to 6min, and the movement direction of the cloud remains the same. Compared with traditional methods, this downscaling approach is a postprocessing method of satellite data with higher precision, which can improve the application value of FY-4A in disaster weather warning.","PeriodicalId":258680,"journal":{"name":"Earth and Space From Infrared to Terahertz (ESIT 2022)","volume":"21 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2023-01-31","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"115321059","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}
L. Liu, Lanbo Liu, Yuanyuan Li, Shiqi Zhu, Yanhong Chai, Chao Lu
The assembly and measurement of quasi-optical feed network has the characteristics of small size, too many components, compact and complex structure. The measurement and assembly process of quasi-optical feed network has the requirements of high accuracy and high reliability. In this paper, focalizing on problems such as great error in the terahertz quasi ellipsoid lens optical feed networks, slow speed and poor reliability in the traditional assembly accuracy. Putting forward a kind of least-squares surface fitting method with parameter constrains, getting the ellipsoidal mirror, long half shaft and other characteristic parameters, the relative error of fitting characteristic parameters is within 0.03%. We adjust the position of the terahertz quasi ellipsoid from lens optical feed networks based on these characteristic parameters. The experimental results show that, by adjusting the proposed surface fitting algorithm, the assembly efficiency of the terahertz quasi-optical feed network is significantly improved compared with the traditional manual adjustment method, and the assembly error of the terahertz quasi-optical network can be effectively reduced. By the end, the high precision assembly of the ellipsoidal mirror of the quasi-optical feed network can be realized.
{"title":"Study of terahertz ellipsoidal lens assembly method based on surface fitting","authors":"L. Liu, Lanbo Liu, Yuanyuan Li, Shiqi Zhu, Yanhong Chai, Chao Lu","doi":"10.1117/12.2664939","DOIUrl":"https://doi.org/10.1117/12.2664939","url":null,"abstract":"The assembly and measurement of quasi-optical feed network has the characteristics of small size, too many components, compact and complex structure. The measurement and assembly process of quasi-optical feed network has the requirements of high accuracy and high reliability. In this paper, focalizing on problems such as great error in the terahertz quasi ellipsoid lens optical feed networks, slow speed and poor reliability in the traditional assembly accuracy. Putting forward a kind of least-squares surface fitting method with parameter constrains, getting the ellipsoidal mirror, long half shaft and other characteristic parameters, the relative error of fitting characteristic parameters is within 0.03%. We adjust the position of the terahertz quasi ellipsoid from lens optical feed networks based on these characteristic parameters. The experimental results show that, by adjusting the proposed surface fitting algorithm, the assembly efficiency of the terahertz quasi-optical feed network is significantly improved compared with the traditional manual adjustment method, and the assembly error of the terahertz quasi-optical network can be effectively reduced. By the end, the high precision assembly of the ellipsoidal mirror of the quasi-optical feed network can be realized.","PeriodicalId":258680,"journal":{"name":"Earth and Space From Infrared to Terahertz (ESIT 2022)","volume":"5 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2023-01-31","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"126374196","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}
Z. Cui, Xingguang Qian, HaoQi Shi, Zongqi Ye, Xue Wang, C. Xing, Ruihong Gao, Jianjun Jia, Yikun Wang, Jianyu Wang
In the Taiji mission, since the transmission distance of the inter-satellite laser link reaches three million kilometers, the wavefront of its laser transmission will be distorted. Therefore, laser interferometric relative distance measurements can be significantly affected by laser-pointing jitter noise. We built a ground verification system based on the Michelson interferometer to verify critical technologies. At the same time, we analyzed the control characteristics of the system from the perspectives of frequency and time domains. In the end, we successfully built the system in the atmospheric environment of the laboratory and carried out related technical verifications. The experimental results show that in the case of 4µrad/√ Hz@10mHz disturbance, the system can suppress the laser pointing jitter noise to 31.2nrad/√ Hz@10mHz (inner ring data) and 385.7nrad/√ Hz@10mHz (outer ring data), and the effect has reached below the noise floor. The experiment promotes the development of pointing system technology based on the Michelson interferometer and provides relevant technical verification for the follow-up Taiji mission.
{"title":"Research on noise suppression of inter-satellite laser pointing jitter","authors":"Z. Cui, Xingguang Qian, HaoQi Shi, Zongqi Ye, Xue Wang, C. Xing, Ruihong Gao, Jianjun Jia, Yikun Wang, Jianyu Wang","doi":"10.1117/12.2664551","DOIUrl":"https://doi.org/10.1117/12.2664551","url":null,"abstract":"In the Taiji mission, since the transmission distance of the inter-satellite laser link reaches three million kilometers, the wavefront of its laser transmission will be distorted. Therefore, laser interferometric relative distance measurements can be significantly affected by laser-pointing jitter noise. We built a ground verification system based on the Michelson interferometer to verify critical technologies. At the same time, we analyzed the control characteristics of the system from the perspectives of frequency and time domains. In the end, we successfully built the system in the atmospheric environment of the laboratory and carried out related technical verifications. The experimental results show that in the case of 4µrad/√ Hz@10mHz disturbance, the system can suppress the laser pointing jitter noise to 31.2nrad/√ Hz@10mHz (inner ring data) and 385.7nrad/√ Hz@10mHz (outer ring data), and the effect has reached below the noise floor. The experiment promotes the development of pointing system technology based on the Michelson interferometer and provides relevant technical verification for the follow-up Taiji mission.","PeriodicalId":258680,"journal":{"name":"Earth and Space From Infrared to Terahertz (ESIT 2022)","volume":"10 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2023-01-31","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"114873327","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}
Shuoying Yu, Y. Cai, Sheng Liu, Yizhen Zhu, Xuehui Lu, C. Jing, Junhao Chu
Hollow optical fiber is an important means for transmitting mid-infrared laser radiations (e.g. 10.6 μm CO2 laser) in medical surgery applications. Presently it’s still a challenge to establish a flexible, low-cost hollow fiber that can transmit the invisible mid-infrared light and the visible indicator light simultaneously. In this work, we selected flexible acrylonitrile butadiene styrene (ABS) plastic tubing and polymethylmethacrylate (PMMA) plastic optical fiber to fabricate a PMMA/ABS plastic tube-based hollow optical fiber. The ABS plastic tube with Ag/AgI plating on the inner surface was used to transmit CO2 laser. The PMMA plastic optical fibers integrated around the output end of the ABS tube-based Ag/AgI hollow fiber was used to deliver visible light. The results show that the CO2 laser transmission loss of this hollow fiber goes up from 0.74 to 1.22 dB/m as the bending angle increases from 0° to 120°. The 5-watt CO2 laser can be transmitted continuously for at least 6 minutes. The illumination of visible light transmitted through the PMMA plastic optical fibers can reach 1171 lux. Compared with conventional silica glass tube-based dual- core hollow fiber, the PMMA/ABS plastic tube-based hollow fiber is more robust, flexible and easy to couple. The PMMA/ABS plastic tube-based hollow optical fiber provides new ideas for transmitting invisible mid-infrared light and the visible indicator light simultaneously, which is expected to build a new laser surgery medical equipment.
{"title":"Structural design and fabrication of hollow optical fiber for transmitting mid-infrared and visible light","authors":"Shuoying Yu, Y. Cai, Sheng Liu, Yizhen Zhu, Xuehui Lu, C. Jing, Junhao Chu","doi":"10.1117/12.2665479","DOIUrl":"https://doi.org/10.1117/12.2665479","url":null,"abstract":"Hollow optical fiber is an important means for transmitting mid-infrared laser radiations (e.g. 10.6 μm CO2 laser) in medical surgery applications. Presently it’s still a challenge to establish a flexible, low-cost hollow fiber that can transmit the invisible mid-infrared light and the visible indicator light simultaneously. In this work, we selected flexible acrylonitrile butadiene styrene (ABS) plastic tubing and polymethylmethacrylate (PMMA) plastic optical fiber to fabricate a PMMA/ABS plastic tube-based hollow optical fiber. The ABS plastic tube with Ag/AgI plating on the inner surface was used to transmit CO2 laser. The PMMA plastic optical fibers integrated around the output end of the ABS tube-based Ag/AgI hollow fiber was used to deliver visible light. The results show that the CO2 laser transmission loss of this hollow fiber goes up from 0.74 to 1.22 dB/m as the bending angle increases from 0° to 120°. The 5-watt CO2 laser can be transmitted continuously for at least 6 minutes. The illumination of visible light transmitted through the PMMA plastic optical fibers can reach 1171 lux. Compared with conventional silica glass tube-based dual- core hollow fiber, the PMMA/ABS plastic tube-based hollow fiber is more robust, flexible and easy to couple. The PMMA/ABS plastic tube-based hollow optical fiber provides new ideas for transmitting invisible mid-infrared light and the visible indicator light simultaneously, which is expected to build a new laser surgery medical equipment.","PeriodicalId":258680,"journal":{"name":"Earth and Space From Infrared to Terahertz (ESIT 2022)","volume":"43 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2023-01-31","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"122176436","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}
Experiments for coherent, wide-tunable frequency and high intensity terahertz (THz) free-electron laser (FEL) generation is under preparation at the Shanghai Soft X-ray FEL facility. In this paper, the effect of high order dispersion on a beat frequency-based THz FEL is presented. Theoretical and simulated analysis are carried out, and the results show that the third order dispersion will produce a cubic modulation on the phase of the seed laser, resulting in a degradation of the FEL performance. During the modulation processes, the nonlinear frequency chirp in the seed laser can lead to heterogeneous bunching structure in the electron beam, which will broaden the spectral bandwidth and reduce the pulse energy of THz radiation. To preserve the properties of the THz radiation, limitations on the phase errors of the seed laser are given.
{"title":"Analysis of high order dispersion effects on a beat frequency-based THz free-electron laser","authors":"Y. Kang, Kaiqing Zhang, C. Feng","doi":"10.1117/12.2664554","DOIUrl":"https://doi.org/10.1117/12.2664554","url":null,"abstract":"Experiments for coherent, wide-tunable frequency and high intensity terahertz (THz) free-electron laser (FEL) generation is under preparation at the Shanghai Soft X-ray FEL facility. In this paper, the effect of high order dispersion on a beat frequency-based THz FEL is presented. Theoretical and simulated analysis are carried out, and the results show that the third order dispersion will produce a cubic modulation on the phase of the seed laser, resulting in a degradation of the FEL performance. During the modulation processes, the nonlinear frequency chirp in the seed laser can lead to heterogeneous bunching structure in the electron beam, which will broaden the spectral bandwidth and reduce the pulse energy of THz radiation. To preserve the properties of the THz radiation, limitations on the phase errors of the seed laser are given.","PeriodicalId":258680,"journal":{"name":"Earth and Space From Infrared to Terahertz (ESIT 2022)","volume":"12505 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2023-01-31","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"129862534","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}
Long-life mechanical refrigeration technology is an important technology which provides support for space scientific researches and exploration. The cryocooler can reduce the background noise and improve the signal-to-noise ratio, sensitivity, and resolution of the optical detector. The cryocoolers play an important role in infrared detection that provide an essential low temperature working environment for infrared detectors and equipment. Nowadays, the sensitivity requirements of infrared detectors have increased, and it is gradually necessary to provide a cooling temperature region below 20 K. It is also necessary to provide cooling in the liquid helium temperature region for the very long waves and microwaves infrared detection. Stirling type pulse tube cryocooler (SPTC) has become one of the most popular mechanical refrigerators due to its advantages of no moving parts at the cold end, low vibration, high stability, and simple structure. In the form of multi-stage coupling, the SPTC can realize the space application in the temperature range of 4-20 K, and a series of multi-stage cryocoolers have been developed in Shanghai Institution of Technical Physics of Chinese Academy of Sciences (SITP, CAS). A two-stage SPTC operating in 20 K (PT2C-20) has been developed for cooling infrared detectors and per-cooling helium JT cryocooler. For easy adjustment and high efficiency, the driven compressor of the SPTC is designed as two independent linear compressors. The second stage cold finger uses an active warm displacer as phase shifter to maximize the cooling performance. By optimizing the operating parameters of the active warm displacer piston and the pre-cooling temperature, the cryocooler can obtain a maximum cooling capacity of 1.31 W at 20 K with the total input electrical power of 470 W and the pre-cooling temperature of 80 K. For the multi-stage pulse tube cryocoolers working at 20 K, the design of the regenerator in the low temperature section is the key to improving the cooling capacity and efficiency of the refrigerator. In order to further lower the no-load temperature and improve the efficiency of the cryocooler at 15 K, we studied the influence of the regenerator in the low temperature section of the second stage pulse tube refrigerator by simulation and experiments. The structural parameters of the regenerator and other key components were optimized and improved, and a new two-stage SPTC (PT2C-15) was designed for the 15 K temperature region. The cryocooler can obtain a cooling capacity of 0.91 W at 15 K with a total input electrical power of 386 W whose cooling capacity and efficiency are greatly improved. In order to realize the applications of liquid helium temperature region, we have developed the three-stage pulse tube cryocooler technology, especially for the large cooling capacities. A third-stage SPTC is thermally coupled with the developed two-stage SPTC (PT2C-20) and successfully obtained a three-stage SPTC (PT3C-7) which can
{"title":"Development of multi-stage Stirling type pulse tube cryocooler below 20 K in SITP, CAS","authors":"Wang Yin, Shaoshuai Liu, Zhenhua Jiang, Zhi Lu, Zheng Huang, Yinong Wu","doi":"10.1117/12.2664532","DOIUrl":"https://doi.org/10.1117/12.2664532","url":null,"abstract":"Long-life mechanical refrigeration technology is an important technology which provides support for space scientific researches and exploration. The cryocooler can reduce the background noise and improve the signal-to-noise ratio, sensitivity, and resolution of the optical detector. The cryocoolers play an important role in infrared detection that provide an essential low temperature working environment for infrared detectors and equipment. Nowadays, the sensitivity requirements of infrared detectors have increased, and it is gradually necessary to provide a cooling temperature region below 20 K. It is also necessary to provide cooling in the liquid helium temperature region for the very long waves and microwaves infrared detection. Stirling type pulse tube cryocooler (SPTC) has become one of the most popular mechanical refrigerators due to its advantages of no moving parts at the cold end, low vibration, high stability, and simple structure. In the form of multi-stage coupling, the SPTC can realize the space application in the temperature range of 4-20 K, and a series of multi-stage cryocoolers have been developed in Shanghai Institution of Technical Physics of Chinese Academy of Sciences (SITP, CAS). A two-stage SPTC operating in 20 K (PT2C-20) has been developed for cooling infrared detectors and per-cooling helium JT cryocooler. For easy adjustment and high efficiency, the driven compressor of the SPTC is designed as two independent linear compressors. The second stage cold finger uses an active warm displacer as phase shifter to maximize the cooling performance. By optimizing the operating parameters of the active warm displacer piston and the pre-cooling temperature, the cryocooler can obtain a maximum cooling capacity of 1.31 W at 20 K with the total input electrical power of 470 W and the pre-cooling temperature of 80 K. For the multi-stage pulse tube cryocoolers working at 20 K, the design of the regenerator in the low temperature section is the key to improving the cooling capacity and efficiency of the refrigerator. In order to further lower the no-load temperature and improve the efficiency of the cryocooler at 15 K, we studied the influence of the regenerator in the low temperature section of the second stage pulse tube refrigerator by simulation and experiments. The structural parameters of the regenerator and other key components were optimized and improved, and a new two-stage SPTC (PT2C-15) was designed for the 15 K temperature region. The cryocooler can obtain a cooling capacity of 0.91 W at 15 K with a total input electrical power of 386 W whose cooling capacity and efficiency are greatly improved. In order to realize the applications of liquid helium temperature region, we have developed the three-stage pulse tube cryocooler technology, especially for the large cooling capacities. A third-stage SPTC is thermally coupled with the developed two-stage SPTC (PT2C-20) and successfully obtained a three-stage SPTC (PT3C-7) which can ","PeriodicalId":258680,"journal":{"name":"Earth and Space From Infrared to Terahertz (ESIT 2022)","volume":"359 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2023-01-31","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"130076737","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}
Yifan Lu, Hongyi Wang, Wengang Tao, Songlei Huang, Xue Li
In order to adapt to the third generation of infrared focal plane readout circuit design, this paper designs a 640x512-5μm InGaAs short-wave infrared focal plane readout circuit design based on 0.18μm standard technology. Based on the analysis of each module, the design focuses on the pixel unit and the readout mode of the array. Noise reduction and gain amplification are realized by pseudo correlation double sampling technology. Finally, the design of four - channel output simulation circuit. According to the simulation results, the readout rate is 10MHz, the system default working frame frequency is 54Hz, the output swing is 1.7V, and the linearity is more than 99.9%.
{"title":"Research on 640x512-5μm InGaAs short-wave infrared focal plane readout circuit","authors":"Yifan Lu, Hongyi Wang, Wengang Tao, Songlei Huang, Xue Li","doi":"10.1117/12.2665816","DOIUrl":"https://doi.org/10.1117/12.2665816","url":null,"abstract":"In order to adapt to the third generation of infrared focal plane readout circuit design, this paper designs a 640x512-5μm InGaAs short-wave infrared focal plane readout circuit design based on 0.18μm standard technology. Based on the analysis of each module, the design focuses on the pixel unit and the readout mode of the array. Noise reduction and gain amplification are realized by pseudo correlation double sampling technology. Finally, the design of four - channel output simulation circuit. According to the simulation results, the readout rate is 10MHz, the system default working frame frequency is 54Hz, the output swing is 1.7V, and the linearity is more than 99.9%.","PeriodicalId":258680,"journal":{"name":"Earth and Space From Infrared to Terahertz (ESIT 2022)","volume":"7 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2023-01-31","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"130258184","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}
Yanhua Zhao, F. Shi, Xiuqian Zhang, Bicen Li, Yan Li
Thermal infrared remote sensing plays an important role in the field of optical remote sensing because it can obtain the radiant brightness temperature of ground objects day and night and provide basic data for quantitative applications such as surface temperature and evapotranspiration. In order to improve the observation efficiency of long-wave infrared remote sensing, after years of pre-research and model engineering development and test verification, a 360° unidirectional uniform rotation scanning mirror is set in front of the optical lens, a small F-number optical lens is configured, and a high-sensitivity quadrangular integrated long-line TDI long-wave detector is set. The on-orbit application of a wide thermal infrared imager with a spatial resolution of 100m, NEΔT better than 0.1K and width better than 1500km in four long wave infrared spectrum segments of 8μm～12.5 μm has been realized, which makes the comprehensive index of thermal infrared optical load in China reach the international advanced level. The stability of the high and low temperature blackbody of the large surface source can reach 20mK/25min, and the temperature difference can reach 21℃, which provides a guarantee for the high-precision radiometric calibration and quantitative application in orbit. The payload can cover most of the regions in China in one day and the whole world in two days, which will greatly improve the application efficiency of thermal infrared remote sensing data, and provide powerful data support for thermal pollution emission monitoring, environmental assessment of nuclear power plants, water temperature monitoring of key rivers and lakes/coastal areas, drought monitoring, fire monitoring, etc.
{"title":"Technical characteristics and application analysis of wide-swath thermal infrared imager","authors":"Yanhua Zhao, F. Shi, Xiuqian Zhang, Bicen Li, Yan Li","doi":"10.1117/12.2666098","DOIUrl":"https://doi.org/10.1117/12.2666098","url":null,"abstract":"Thermal infrared remote sensing plays an important role in the field of optical remote sensing because it can obtain the radiant brightness temperature of ground objects day and night and provide basic data for quantitative applications such as surface temperature and evapotranspiration. In order to improve the observation efficiency of long-wave infrared remote sensing, after years of pre-research and model engineering development and test verification, a 360° unidirectional uniform rotation scanning mirror is set in front of the optical lens, a small F-number optical lens is configured, and a high-sensitivity quadrangular integrated long-line TDI long-wave detector is set. The on-orbit application of a wide thermal infrared imager with a spatial resolution of 100m, NEΔT better than 0.1K and width better than 1500km in four long wave infrared spectrum segments of 8μm～12.5 μm has been realized, which makes the comprehensive index of thermal infrared optical load in China reach the international advanced level. The stability of the high and low temperature blackbody of the large surface source can reach 20mK/25min, and the temperature difference can reach 21℃, which provides a guarantee for the high-precision radiometric calibration and quantitative application in orbit. The payload can cover most of the regions in China in one day and the whole world in two days, which will greatly improve the application efficiency of thermal infrared remote sensing data, and provide powerful data support for thermal pollution emission monitoring, environmental assessment of nuclear power plants, water temperature monitoring of key rivers and lakes/coastal areas, drought monitoring, fire monitoring, etc.","PeriodicalId":258680,"journal":{"name":"Earth and Space From Infrared to Terahertz (ESIT 2022)","volume":"23 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2023-01-31","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"115769019","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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