2021
2021
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Record 121 of
Title:Adjustment of optical axis consistency of spatial rotation in laser coupling
Author(s):Cao, Ming Qiang(1); Li, Xiao Yan(1); Hou, Xiao Hua(1); Zhang, Ge(1); Lei, Yu(1); Fu, Xi Hong(1)Source: Proceedings of SPIE - The International Society for Optical Engineering Volume: 12060 Issue: DOI: 10.1117/12.2607091 Published: 2021Abstract:The laser transceiver contains a lot of complex optical refractors. The laser signal is emitted from the laser, transmitted through the optical fiber and the transceiver, and entered into the air after multiple splitting, reflection and expansion, so as to exchange information with the outside world. The direction of the laser axis changes with the motion of the two-dimensional turntable. In the process of coupling between the laser fiber and the transceiver, the parallel light generated by the receiving and transmitting collimator should be meet the requirements of consistent divergence angel, parallelism and coincidence at the light outlet of the device. In this paper, the method optical axis consistency detection and adjustment in the process of laser coupling and turntable integration is studied, the device for determining the optical axis reference is designed. By means of precise adjustment, the optical axis and the reference device coincide precisely, and the detection and debugging of optical axis paralleling and coincidence are realized. ? 2021 SPIE.Accession Number: 20220211446994 -
Record 122 of
Title:Design of deployment systems for high-resolution deployable telescope based on CubeSat
Author(s):Dai, Haobin(1,2); Li, Chuang(1); Li, Liangliang(1,2); Hu, Bin(1,2); Yao, Pei(1,2)Source: Proceedings of SPIE - The International Society for Optical Engineering Volume: 12069 Issue: DOI: 10.1117/12.2606896 Published: 2021Abstract:In this paper, the deployment systems of a deployable space telescope for CubeSat are proposed. This telescope can achieve a ground resolution less than 1 meter at an orbital altitude of 400 km. Both the primary and secondary mirrors of it can be stowed in 3U volume 1/4 100mm×100mm×300mm during launching period. The functions of the deployment systems include the locking of the primary and secondary mirrors when stowed, the deployment on-orbit, and the active adjustment of the primary mirror segments after deployment. In this paper, firstly, the optical system of deployable telescope is described, then the deployment systems of the telescope are designed. Finally, the modal analysis is carried out using finite element method. ? COPYRIGHT SPIE. Downloading of the abstract is permitted for personal use only.Accession Number: 20220211444611 -
Record 123 of
Title:A pupil location algorithm based on cascaded Haar feature and OTSU dynamic threshold segmentation
Author(s):Qian, Fanxing(1,2); Lei, Hao(1,2)Source: Proceedings of SPIE - The International Society for Optical Engineering Volume: 12065 Issue: DOI: 10.1117/12.2607002 Published: 2021Abstract:With the development of visual human-computer interaction, non-invasive eye-tracking technology has been applied in medical diagnosis, psychological research, augmented reality and other fields. As a key step of video-based eye tracking technology, pupil detection requires strong robustness, real-time performance and high precision. Although many pupil detection algorithms have been developed, pupil detection is still a challenge when there are so many interference factors such as bright light, reflection, eyelid or eyelash occlusion, or low image resolution. Aim to address the above difficult problems of pupil detection, this paper uses cascaded Haar features and Otsu dynamic threshold segmentation to improve the performance of the existing pupil detection algorithm. The performance of the improved algorithm is verified with the public human eye image dataset from Swirski with high off-axis and severe eyelash occlusion. The results show that the accuracy of the improved algorithm is 86.3% and 89.7% in the error range of 5 pixels and 10 pixels, respectively. The detection algorithm in this paper can provide accurate pupil center coordinates for eye tracking, which lays a foundation for the high-precision calibration and measurement of the following eye tracker. ? 2021 SPIE.Accession Number: 20220211437976 -
Record 124 of
Title:Research on passive ranging technology based on wave front coding
Author(s):Mi, Jiao(1,2); Zhao, Hui(2)Source: Proceedings of SPIE - The International Society for Optical Engineering Volume: 12065 Issue: DOI: 10.1117/12.2606772 Published: 2021Abstract:Optical passive ranging is based on the light signal radiated by the object itself. The application of wave front coding technology to passive ranging systems simplifies the system structure and improves the ranging accuracy to a large extent. In this paper, the orthogonal coding passive ranging system with the cosine form of the mask function is investigated, and the optical transfer function and the light intensity distribution at the distances of 1m-4m and 1km-5km are simulated by numerical simulation to verify the rationality of the orthogonal coding ranging system, and the measurement error is about. ±0.1m. ? 2021 SPIE.Accession Number: 20220211437956 -
Record 125 of
Title:Fully Unsupervised Person Re-Identification by Enhancing Cluster Samples
Author(s):Chen, Xiumei(1,2); Zheng, Xiangtao(1); Zhu, Kaijian(3); Lu, Xiaoqiang(1)Source: ACM International Conference Proceeding Series Volume: Issue: DOI: 10.1145/3507971.3507984 Published: December 16, 2021Abstract:Fully unsupervised person re-identification aims to train a discriminative model with unlabeled person images. Most existing methods first generate pseudo labels by clustering image features (convolutional features) and then fine-tune the convolutional neural network (CNN) with pseudo labels. However, these methods are greatly limited by the quality of the pseudo labels. In this paper, a cluster sample enhancement method is introduced to increase the reliability of pseudo-label samples to facilitate the CNN training. Specifically, when generating pseudo labels, only the samples with high-confidence pseudo-label predictions are selected. In addition, to enhance the selected samples for training, two different image transformations are adopted and coupled with specific-design loss functions to boost the model performance. Experiments demonstrate the effectiveness of the proposed method. Concretely, the proposed method achieves 87.1% rank-1 and 70.2% mAP accuracy on Market-1501. ? 2021 ACM.Accession Number: 20221311871695 -
Record 126 of
Title:Systematic Research on Measuring Acceleration of Gravity by Laser Interferometry
Author(s):Dang, Chun(1); Li, Jing(1); Tang, Jie(2)Source: Journal of Physics: Conference Series Volume: 1982 Issue: 1 DOI: 10.1088/1742-6596/1982/1/012146 Published: August 2, 2021Abstract:Gravity acceleration is an important physical quantity, and its precise measurement results have important applications in practice. According to the principle of measuring gravity acceleration in college physics experiment, a scheme of measuring gravity acceleration by laser interferometry is designed, and the main sources and sizes of experimental errors are analyzed and calculated. Compared with the common simple pendulum method and falling body method, the theoretical results show that our measurement method has higher precision and is feasible to accurately measure the acceleration of gravity. ? Published under licence by IOP Publishing Ltd.Accession Number: 20213410791987 -
Record 127 of
Title:Research on UAV target localization technology based on master INS information transfer alignment
Author(s):Chen, Ying(1); Kang, Zhen(1); Xue, Yuanyuan(1); Du, Juan(2)Source: Proceedings of SPIE - The International Society for Optical Engineering Volume: 12065 Issue: DOI: 10.1117/12.2602142 Published: 2021Abstract:In order to improve the target localization accuracy for unmanned aerial vehicle(UAV), a novel resolved case for target accurately localization is proposed using slave-INS which is fixed on electro-optical reconnaissance system. The work flow of this case is presented, the coordinate transformation relation in target localization process is deduced. According to requirement, a slave-INS alignment on moving base using master INS data is designed. Carry out experiment upon vehicular navigation system, the error convergence of azimuth accelerated obviously. The accuracy of azimuth reaches about 0.1°(1 s). Experiment results show that the localization accuracy for ground target can reach 6m when UAV flies at about 3500m above ground and slant distance is 3700m. the INS has convenience and flexible use which meet to requirement of target localization in electro-optical reconnaissance system on UAV. The accuracy of localization can be increased prominently when this INS is applied to target localization technology. With great practical value. ? 2021 SPIE.Accession Number: 20220211438057 -
Record 128 of
Title:Design of optical system for laser fusion shock velocity measurement
Author(s):Yan, Ya-Dong(1); Wei, Ming-Zhi(1); Li, Qi(1); Wang, Wei(1); Qi, Wen-Bo(1); He, Jun-Hua(1)Source: Guangxue Jingmi Gongcheng/Optics and Precision Engineering Volume: 29 Issue: 2 DOI: 10.37188/OPE.20212902.0259 Published: February 2021Abstract:To meet the demands of laser fusion shock velocity measurements, a composite system that integrates a passive scanning optical pyrometer with an active shock wave velocity interferometer was designed in this study. The common-path lens was achromatic and designed in the range of 400-700 nm by using several types of radiation resistance optical materials. The mirrors of a Mach-Zehnder interferometer were motorized and could be controlled remotely, thereby simplifying the operation of the system. In addition, the system magnification could be altered by using different focal lengths with a streak camera coupling lens. The field of view of the combined system is 2 mm, and the magnification settings for the active velocity measuring system are 10×, 20×, and 30×. The static interference fringes are straight, and their contrast is greater than 0.69. The system has a 4.72 μm spatial resolution. The system can be applied to dynamic measurement of shock velocity in a laser fusion device. ? 2021, Science Press. All right reserved.Accession Number: 20211410160113 -
Record 129 of
Title:The Research of Φ1400mm Sic Mirror for Fabrication, Test and Alignment
Author(s):Liangjie, Feng(1); Gangyi, Zou(1); Pengfei, Cheng(1); Renguorui(1); Wei, Wang(1)Source: Proceedings of SPIE - The International Society for Optical Engineering Volume: 12070 Issue: DOI: 10.1117/12.2605024 Published: 2021Abstract:A Φ1400mm silicon carbide(SiC) mirror assembly was designed according to the requirement of the mass and the optical surface distortion. The parameters of the light-weighted open-back primary mirror were optimized by finite element analysis. Six flexure bipods were designed to support the mirror edge in 12 points evenly. 12 floating anti-gravity supports were used to Minimize the optical surface distortion caused by gravity effect to obtain the real optical surface during polishing. The mirror was precisely assembled with the bipods supports and the Carbon fiber reinforcement plastic (CFRP) chamber. The optical test with interferometer showed that the surface distortion was less than 0.03λ(λ=632nm) RMS with ±5℃ temperature variation and 1g gravity condition, and the mass was 145kg, which coincided with the FEA results. ? 2021 SPIEAccession Number: 20220811682268 -
Record 130 of
Title:Fusion method of multispectral and panchromatic images based on NSST and improved PCNN
Author(s):Song, Chong(1,2); Zeng, Litang(3); Jiang, Kai(1); Liu, Zhaohui(1); Zhou, Liang(1)Source: Proceedings of SPIE - The International Society for Optical Engineering Volume: 11915 Issue: DOI: 10.1117/12.2605896 Published: 2021Abstract:The dual-camera coded aperture snapshot spectral imager(DC-CASSI) includes the coded aperture snapshot spectral imager(CASSI) and panchromatic imager. CASSI can obtain the three-dimensional spectral image information of the target in a single coding within a single integral time, but it is difficult to achieve high-quality reconstruction of spectral image in a single coding. Therefore, the panchromatic image acquired by the panchromatic imager should be fused with it to obtain high-quality multispectral reconstruction images. Based on the imaging characteristics of DC-CASSI, a multispectral and panchromatic image fusion algorithm based on Non-subsampled Shearlets Transform (NSST) and improved Pulse Coupled Neural Network(PCNN) is proposed. The fusion experimental results show that compared with other traditional fusion algorithms, the proposed fusion algorithm can be well applied to DC-CASSI and maximum improving the spatial resolution of multispectral coded image while preserving spectral characteristics of the multispectral coded image. ? 2021 SPIE.Accession Number: 20214611146487 -
Record 131 of
Title:Stable and oscillating solitons of PT -symmetric couplers with gain and loss in fractional dimension
Author(s):Zeng, Liangwei(1,2); Shi, Jincheng(3); Lu, Xiaowei(1,2); Cai, Yi(1,2); Zhu, Qifan(1,2); Chen, Hongyi(1,2); Long, Hu(1,2); Li, Jingzhen(1,2)Source: arXiv Volume: Issue: DOI: null Published: April 14, 2021Abstract:Families of coupled solitons of PT -symmetric physical models with gain and loss in fractional dimension and in settings with and without cross-interactions modulation (CIM), are reported. Profiles, powers, stability areas, and propagation dynamics of the obtained PT -symmetric coupled solitons are investigated. By comparing the results of the models with and without CIM, we find that the stability area of the model with CIM is much broader than the one without CIM. Remarkably, oscillating PT -symmetric coupled solitons can also exist in the model of CIM with the same coefficients of the self- and cross-interactions modulations. In addition, the period of these oscillating coupled solitons can be controlled by the linear coupling coefficient. Copyright ? 2021, The Authors. All rights reserved.Accession Number: 20210104564 -
Record 132 of
Title:Numerical simulation study on gain nonlinearity of microchannel plate in photomultiplier tube
Author(s):Guo, Lehui(1); Chen, Ping(1); Li, Lili(1); Gou, Yongsheng(1); Liu, Hulin(1); Liu, Ziyu(1); Xin, Liwei(1); Tian, Jinshou(1)Source: IEEE Transactions on Nuclear Science Volume: 68 Issue: 12 DOI: 10.1109/TNS.2021.3121583 Published: December 1, 2021Abstract:Microchannel plate-photomultiplier tubes (MCP-PMTs) with high dynamic ranges and strong outputs are still challenges for the future inertial confinement fusion (ICF) studies, aiming at detecting the large-scale intensities of the radiation pulses. In this article, to investigate the influence factors of the gain nonlinearity causing high-linearity limits of the MCP-PMTs, 3-D microchannel plate (MCP) channel models were built in computer simulation technology (CST) Particle Studio. The Monte Carlo and particle-in-cell methods were carried out to simulate the electron cascade processes in the channels of the MCPs. The dependences of MCP gain nonlinearity on the number of incident electrons, operating voltage, and secondary electron emission (SEE) yield properties were studied. The gains obtained by the simulations for the conventional one-stage and two-stage MCPs are in good agreement with the available experimental data, which verifies the reliabilities of the 3-D MCP models. The simulation results show that the gain of the MCP single channel decreases as the number of incident electrons increases due to the space charge effects. The higher the operating voltage and SEE yield of the MCP, the faster the gain deteriorates. To mitigate the gain saturation effect of MCP single channels, a novel structural design of MCP-PMTs has been proposed by adjusting the design of the MCP chevron pair. A significant improvement in the output pulse peak can be obtained. 0018-9499 ? 2021 IEEE.Accession Number: 20214411103438