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Record 349 of
Title:Design and Test of Thermo Electric Cooling System for Space Based Telescope Detector Assembly
Author(s):Yang, Wen-Gang(1,2); Fan, Xue-Wu(1); Wang, Chen-Jie(1); Qin, De-Jin(1); Li, Bao-Peng(1,2); Du, Yun-Fei(1); Feng, Liang-Jie(1); Zhao, Hui(1); Gao, Wei(1)
Source: Guangzi Xuebao/Acta Photonica Sinica Volume: 49 Issue: 8 DOI: 10.3788/gzxb20204908.0822001 Published: August 1, 2020
Abstract:Active cooling must be utilized to meet the need for the space-based telescope which need very low detector noise level. The precise thermal control measures based on thermo-electric cooling technique are utilized and especially the package system and heat rejection system of thermo-electric coolers and its cotroller system are designed respectively. The parasitic heat load to the detector and the heat path resistances are optimized to reduce the input power and the radiator size. Based on the Peltier effect and Joule effect and Frourie effect, the relations between the enviroments parameters and working parameters are analyzed. The enviroments parameters include the heat pumped requirements, the thermal resistance between the hot side and the sink and the hot side sink temperature, while the working parameters include the current, voltage and input power of coolers. The sensitivity between the heat loads, thermal resistance and the input power are especially researched. The qualification model of the telescope is developed and the thermal vaccum and balance test are accomplished. The test results show that the system design are appropriate and effective, the detector temperature is controlled at -75±0.2℃. Based on the test environments conditions and the cooler's working parameters, the thermal analysis model are discussed and corrected.These lessons can provide some reference for the development of thermo-electric cooling system of the similar space based telescope. ? 2020, Science Press. All right reserved.
Accession Number: 20203709159457
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Record 350 of
Title:Dependence of interferogram phase on incident wavenumber and phase stability of Doppler asymmetric spatial heterodyne spectroscopy
Author(s):Zhang, Ya-Fei(1,2); Feng, Yu-Tao(1); Fu, Di(1); Wang, Peng-Chong(1); Sun, Jian(1); Bai, Qing-Lan(1)
Source: Chinese Physics B Volume: 29 Issue: 10 DOI: 10.1088/1674-1056/ab9de8 Published: September 2020
Abstract:Instrument drifts introduce additional phase errors into atmospheric wind measurement of Doppler asymmetric spatial heterodyne spectroscopy (DASH). Aiming at the phase sensitivity of DASH to instrument drifts, in this paper we calculate the optical path difference (OPD) and present an accurate formula of DASH interferogram. By controlling variables in computational ray-tracing simulations and laboratory experiments, it is indicated that initial phase is directly determined by incident wavenumber, OPD offset and field of view (FOV). Accordingly, it is indicated that retrieved phase of DASH is sensitive to slight structural change caused by instrument drift, which provides the proof of necessary-to-track and -correct phase errors from instrument drifts. ? 2020 Chinese Physical Society and IOP Publishing Ltd.
Accession Number: 20204409426823
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Record 351 of
Title:Development of Laser Beam Expanding Collimator for Cold Atom Preparation
Author(s):Hao, An-Qing(1,2); Jia, Sen(1); Xie, Lai-Yun(1); Cai, Yong(1); Wang, Xian-Hua(1)
Source: Guangzi Xuebao/Acta Photonica Sinica Volume: 49 Issue: 3 DOI: 10.3788/gzxb20204903.0314002 Published: March 1, 2020
Abstract:Aiming at the defect that most polarization-maintaining fiber input beam expander collimators used in cold atom experiments can not accurately adjust the polarization of the input laser beam, a compact polarization-adjustable laser beam expanding collimator with a full length of 135 mm and an effective diameter of 20 mm for the output circular spot is proposed. The polarization axes of the polarization prism and the wave plate in the beam expander collimator can be independently adjusted, and the polarization state of the input beam of the single-mode polarization maintaining fiber can be accurately adjusted and maintained. The developed laser beam expanding collimator has prepared cold atomic groups that meet the requirements of cold atom interference experiment in the cold atom experiment of three-dimensional magneto-optical trap. The atomic number of cold atomic groups was 5×108, the temperature was about 10 μK, and the flight time signal of atomic fountain with the maximum throw-up height of 1.156 m was obtained. ? 2020, Science Press. All right reserved.
Accession Number: 20201508406566
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Record 352 of
Title:Research on adaptive pulse signal extraction algorithm based on fingertip video image
Author(s):Yu, Jiangjun(1,2); Zhou, Liang(1); Liu, Zhaohui(1); Li, Zhiguo(1); Shan, Qiusha(1)
Source: Shengwu Yixue Gongchengxue Zazhi/Journal of Biomedical Engineering Volume: 37 Issue: 1 DOI: 10.7507/1001-5515.201901038 Published: February 25, 2020
Abstract:In order to solve the saturation distortion phenomenon of R component in fingertip video image, this paper proposes an iterative threshold segmentation algorithm, which adaptively generates the region to be detected for the R component, and extracts the human pulse signal by calculating the gray mean value of the region to be detected. The original pulse signal has baseline drift and high frequency noise. Combining with the characteristics of pulse signal, a zero phase digital filter is designed to filter out noise interference. Fingertip video images are collected on different smartphones, and the region to be detected is extracted by the algorithm proposed in this paper. Considering that the fingertip's pressure will be different during each measurement, this paper makes a comparative analysis of pulse signals extracted under different pressures. In order to verify the accuracy of the algorithm proposed in this paper in heart rate detection, a comparative experiment of heart rate detection was conducted. The results show that the algorithm proposed in this paper can accurately extract human heart rate information and has certain portability, which provides certain theoretical help for further development of physiological monitoring application on smartphone platform. Copyright ? 2020 by Editorial Office of Journal of Biomedical Engineering.
Accession Number: 20201208317960
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Record 353 of
Title:High-speed focusing and scanning light through multimode fiber
Author(s):Geng, Yi(1,2); Zhang, Zaikun(1,2); He, Zhengquan(1); Chen, Hui(1,2); Wang, Ruiduo(1,2); Kong, Depeng(1); Guo, Haitao(1)
Source: Proceedings of SPIE - The International Society for Optical Engineering Volume: 11717 Issue: DOI: 10.1117/12.2586318 Published: 2020
Abstract:The image distortions caused by the inherent mode dispersion and coupling of the multimode fiber (MMF) lead its output light field to be scattered and prevent it from applicating in endoscopy. Although various wavefront shaping methods have been proposed to overcome these image distortions and form the focused spots through the MMF, they a re usually time-consuming due to the multiple iterations and tedious calculation. In this paper, we present a binary amplitude-only modulation parallel coordinate algorithm for focusing and scanning light through a multimode fiber (MMF) based on the digital micro-mirror device (DMD) in a reference-free multimode fiber imaging system. In principle, our algorithm is capable of efficiently calculating the masks to be added to DMD for yielding a series of tightly focused spots; and for the same number of modulation sub-regions, our method is more than M (the number of focused spots) times faster than the amplitude iterative optimization algorithm. In the experiment, efficient light focusing and scanning at the distal end of the MMF without the iteration process are demonstrated. Furthermore, we demonstrate that the proposed method can also be extended to focus and scan light at multiple planes along the axial direction by just modifying the input wavefront accordingly. We predict the high-speed focusing method through the MMF might have the potential application for fast spot-scanning imaging. ? 2020 SPIE.
Accession Number: 20210109714275
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Record 354 of
Title:Research on compact design and reduced structure analysis of a small camera for ocean remote sensing
Author(s):Song, Yang(1); Hu, Bin(1,2); Chai, Wenyi(1); Zou, Gangyi(1,2); Hu, Yongming(1)
Source: Proceedings of SPIE - The International Society for Optical Engineering Volume: 11571 Issue: DOI: 10.1117/12.2576285 Published: 2020
Abstract:The status of ocean remote sensing is becoming more and more important. There are all kinds of resources in ocean and many ships on the sea. It is necessary for people to detect or observe these objects to know more about the natural resources and to ensure safety of ships. The paper concentrated on a compact design of a small space camera. An oscillating mirror was designed in the camera for a small volume. After that, structure analysis was done by traditional method and reduced method. The key step of reduced method was to get the reduced model. The analysis result showed that the reduced method could not only cut down the cost of computing, but also give a result with good accuracy. Besides, the analysis result indicated that the small space camera could undergo the strict load cases smoothly. The design in this paper may give some guidance to other designers and engineers when they are going to make a small space camera for ocean remote sensing. ? COPYRIGHT SPIE. Downloading of the abstract is permitted for personal use only.
Accession Number: 20204709520722
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Record 355 of
Title:3D Imaging Restoration of Spinning-Disk Confocal Microscopy Via Deep Learning
Author(s):Bai, Chen(1); Yu, Xianghua(1); Peng, Tong(1); Liu, Chao(1); Min, Junwei(1); Dan, Dan(1); Yao, Baoli(1)
Source: IEEE Photonics Technology Letters Volume: 32 Issue: 18 DOI: 10.1109/LPT.2020.3014317 Published: September 15, 2020
Abstract:Due to the multipoint excitation and simultaneous detection strategy applied, spinning-disk confocal microscopy (SDCM) results in an increased imaging speed compared to conventional confocal microscopy. Additionally, the super-resolution radial fluctuations (SRRF) approach can further improve the imaging resolution of SDCM in 3D imaging at the cost of imaging time due to the large amounts of data acquisition and the increased risk of photo-bleaching and photo-toxicity due to the multiple excitations. Here, we propose a deep learning-based method for 3D SDCM, where the neighboring pixels in $z$ -scanning slices are taken into account for 3D reconstruction. Consequently, high-quality imaging slices can be reconstructed directly from the SDCM stacks with a single scan. The image quality achievable with this SRRF-Deep method is comparable with the SRRF method, whereas it achieves image reconstruction about 30 times faster using 100 times fewer images. Thus, practicality of the SDCM system can be significantly improved in 3D imaging. ? 1989-2012 IEEE.
Accession Number: 20203609137731
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Record 356 of
Title:Large diameter optics support optimization based on finite element method and optical surface fitting with zernike method
Author(s):Liang-Xiao, Zhao(1,2); Jian, Zhang(1,3); San-Feng, Hao(1,2); Li-Min, Gao(1)
Source: Proceedings of SPIE - The International Society for Optical Engineering Volume: 11568 Issue: DOI: 10.1117/12.2574631 Published: 2020
Abstract:Large aperture optical element deformed by its own weight is caused is one of the important considerations when we design the optical system, designing a mirror support solution that reduces the effects of gravity is critical.Traditional methods cannot effectively and intuitively analyze mirror distortion.In this paper, the finite element method and the optical surface fitting with zernike polynomial are used to optimize the support scheme. These two methods are mutually verified and this method which use two parts is verified by the optimization scheme of the Φ900mm standard spherical mirror.With optimization, the steel belt loading and unloading weight hammer support scheme is finally adopted, and the best solution with Φ705mmin the circumference and each aperture is 55mm on the back of the mirror is obtained. The theoretical mirror surface's PV and RMS value equal to7.36nm (1/86λ) and 1.64nm (1/386λ), which is a good basis for guiding production. ? 2020 SPIE. All rights reserved.
Accession Number: 20204909580440
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Record 357 of
Title:Point-ahead analysis and pre-pointing link stability study of intersatellite laser communication
Author(s):Zhang, Fu-Rui(1,2); Han, Jun-Feng(1); Ruan, Ping(1)
Source: Optica Applicata Volume: 50 Issue: 1 DOI: 10.37190/OA200109 Published: 2020
Abstract:The static bias error angle obviously affects pre-pointing links' stability in the presence of vibration in intersatellite laser communication. The 2nd order point-ahead angle is a source of misalignment which was ignored in most solutions, and this is the concern of our paper. In this study, we present a further analytical investigation into the point-ahead angle in complex satellite maneuvering environment. Static bias error angle induced by the 2nd order point-ahead angle has been studied under different intersatellite links. The probability density function of the pre-pointing links' outage has been derived in the presence of pointing jitter taking consideration of the static bias angle, and the link budget has also been analyzed. Simulation model of link stability has been established to verify the numerical results by the Monte Carlo method in Matlab-Simulink environment. The results have shown that the 2nd order point-ahead angle has a significant detrimental impact on link stability in long distance links. It is a neglectable factor. This work is dedicated to intersatellite laser communication system design. ? 2020 Wroc??aw University of Science and Technology. All rights reserved.
Accession Number: 20203008974485
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Record 358 of
Title:Simulation Study on Spectral Characteristics of Skin Tissue and Volume Pulse Wave in 400~1 000 nm Wavelength
Author(s):Zhou, Liang(1); Yu, Jiang-Jun(1,2); Liu, Zhao-Hui(1); Li, Zhi-Guo(1); Shan, Qiu-Sha(1)
Source: Guang Pu Xue Yu Guang Pu Fen Xi/Spectroscopy and Spectral Analysis Volume: 40 Issue: 4 DOI: 10.3964/j.issn.1000-0593(2020)04-1071-05 Published: April 1, 2020
Abstract:According to the anatomical structure of the skin tissue, we established a six-layer model, and the characteristic parameters of each layer of skin tissue were given. We considered the absorption characteristics of oxidized hemoglobin and reduced hemoglobin, and gave the spectral absorption coefficients of each layer of skin tissue according to the contents of water, blood, fat and oxygen saturation in each layer of skin tissue, as well as the size of blood vessels. The scattering coefficients at different wavelengths were simplified properly, and then the scattering coefficient spectra of each layer of skin tissue were obtained. In this paper, we used Monte Carlo method to simulate the transmission process of 400~1 000 nm wavelength light in the multi-layer model of skin tissue under the conditions of contraction and relaxation. The spectral reflectance of the skin tissue was obtained by counting the distribution characteristics of a large number of photons. The amplitude spectrum of volume pulse wave was obtained by calculating the reflection coefficient of the two states obtained from the simulation. The simulation results showed that the volume pulse wave amplitude of green light is better than that of red light and blue light when the incident light intensity is constant. The penetration depth spectrum of skin tissue was obtained by calculating the corresponding skin tissue depth when the light flux of different wavelengths decreased to 1/e along the direction of skin tissue depth. The results showed that the penetration depth of blue light and green light is small, the blue light can only reach the surface layer, the green light can reach the micro-circulation layer, and the penetration depth of red light is the largest, which can reach the dermis directly. Considering when the light travels through the skin, it involves a dynamic process from contraction to relaxation, so we define the depth of pulse signal generation based on penetration depth, and the spectral generation depth is calculated by using the penetration depth of vasodilation and contraction in two different states. The results showed that the depth of light generation at different wavelengths is greater than the penetration depth, the depth of blue light is shallowand the blood absorption modulation is small, so the pulse signal obtained is more easily interfered by noise. The volume pulse wave of red light is deeper than that of green light, but compared with green light, its absorption and modulation by blood is smaller, and the depth of green light generation is enough to reach the dermis vascular layer, so the amplitude of red light volume pulse wave is smaller than that of green light. Our simulation results confirm some spectral characteristics of skin tissue, which provides a theoretical basis for the accurate acquisition of multispectral volume pulse waves and other related studies. ? 2020, Peking University Press. All right reserved.
Accession Number: 20202208742411
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Record 359 of
Title:Tracing and implementation of IMM Kalman filtering feed-forward compensation technology based on neural network
Author(s):Lin, Di(1,2); Wu, Yi-ming(1)
Source: Optik Volume: 202 Issue: DOI: 10.1016/j.ijleo.2019.163574 Published: February 2020
Abstract:UAV has great varieties, large controllable velocity and angular velocity, which makes high requirements on automatically identifying capability and tracking accuracy of ground search and tracking system. It happens frequently that servo feed-forward compensation technology is added in the search and tracking system to improve the tracking accuracy. However, accurate estimations of target velocity and acceleration becomes the difficult point of controlling feed-forward compensation technology. This paper proposes to adopt IMM Kalman filter technology based on neural network to estimate velocity and acceleration of the moving targets, which served as input variable of the servo feed-forward compensation system to eliminate the error of the missing distance caused by velocity and acceleration. Neural network can identify target types and makes self-adaptive adjustment on IMM Kalman filter parameters, which is helpful to improve estimation accuracy. Experimental results show that IMM Kalman filter feed-forward compensation technology based on neural network in the search and tracking system can improve the tracking accuracy of the system by more than 3 times than the conventional Kalman filter compensation, and the model verification is effective. ? 2019 Elsevier GmbH
Accession Number: 20194507626522
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Record 360 of
Title:Design of flexure support for high-precision base plates on hard X-ray imager
Author(s):Feiyang, Zhang(1,2); Fu, Li(1)
Source: Proceedings of SPIE - The International Society for Optical Engineering Volume: 11570 Issue: DOI: 10.1117/12.2580082 Published: 2020
Abstract:An attempt has been made to propose a flexure-based support of the high-precision base plates on Hard X-ray Imager (HXI), which is designed to investigate the non-thermal high-energy electrons accelerated in solar flares. This flexure support is designed to compensate thermal strain, which can lead to an unacceptable reduction of surface accuracy under rigid constraint. The flexure support proposed in this article is made up of eight separated single-side filleted flexure leaves, which are small and easy to manufacture. The flexure leaf's compliance matrix is derived from Castigliano's second theorem. Then the matrix is used, along with Finite Element Analysis (FEA), to determine the critical dimension of the flexure leaves. According to the result of finite element simulation, under a temperature change of ±5K, the inplane torsion angle of the installation sites of grids are reduced to within 10 arcsec using flexure support. And the firstorder natural frequency of the base plate with flexure support is 184 Hz, which is higher than the natural frequency and external disturbance frequency of general satellite carriers. ? 2020 SPIE. All rights reserved.
Accession Number: 20204909580483
