2022
2022
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Record 241 of
Title:Analysis of Influence of Doppler Asymmetric Spatial Heterodyne Interferogram Distortion on Phase Inversion Accuracy
Author(s):Zhou, Guan(1,2); Li, Libo(1); Fu, Di(1); Zhang, Yafei(1,2); Feng, Yutao(1); Liu, Changhai(3)Source: Guangzi Xuebao/Acta Photonica Sinica Volume: 51 Issue: 6 DOI: 10.3788/gzxb20225106.0601001 Published: June 1, 2022Abstract:The wind information of the middle and upper atmosphere is very important to study the coupling of the upper and lower atmosphere and energy， to ensure the smooth development of spacecraft space activities， and to carry out medium and long-term meteorological predictions. The doppler asymmetric spatial heterodyne wind measurement technology is a technique based on the Fourier transform of the interferogram to realize the detection of the doppler frequency shift of the wind. Doppler asymmetric spatial heterodyne is a new passive wind detection technology. For the interferometer， the processing and assembly errors of optical components and structural components， and the aberration of the optical system will distort the interference image. Introducing inversion error in the process of wind speed measurement. The current research on DASH interferogram distortion has not analyzed the influence of interferogram distortion on the accuracy of Doppler phase inversion and lacks the quantitative theoretical basis for the design， processing， and adjustment of Doppler asymmetric spatial heterodyne. In this paper， we analyzed the sources of different distortion in Doppler asymmetric spatial heterodyne. Then by adding different types and sizes of interferogram distortions to the interferograms of the red and green oxygen emission line， the simulation compares the difference between the distorted interferogram’s and the ideal interferogram’s Doppler phase. By adding optical distortion， local bending， slanted fringes and frequency changed these four different forms of interferogram distortion， we got the influence of distortion on the accuracy of Doppler phase inversion. The results show that the Doppler phase error will increase with the increase of the target wind field and interferogram distortion. The Doppler phase error of optical distortion is also will increase with the increase of the target wind field but will fluctuate increase with the increase of interferogram distortion. Among these four different forms of interferogram distortion， the local bending of fringes has the greatest influence on Doppler phase inversion. The phase error increases by 0.113‰ for each additional pixel of the local bending. But the maximum phase error is only 0.03‰ under the condition of 2% distortion. To further explore the influence of local bending sizes and location， we simulate various interferograms with local bending of different sizes and locations. The result shows that the Doppler phase error fluctuation decreases and gradually converges when the size increases. And the phase error fluctuates with the change of position. The fluctuation amount in the first half is small， and the fluctuation in the second half increases gradually. The phase error generated by the same bending at the sampling center is larger than that at the sampling edge. Therefore， attention should be paid to the small distortion in the sampling center area， and if necessary， interferogram correction should be performed to reduce the phase error. The simulation of errors caused by local bending on systems with different fringe frequencies shows that the same amount of bending will have a greater impact on systems with high fringe frequencies. In addition， interferogram with a low signal-to-noise ratio usually uses multiple rows of pixels of the interferogram to reduce uncertainty of phase. Local modulation is reduced when multiple rows of pixels of the distorted interferogram are merged. In order to find out the actual impact of the distorted interferogram in multiple rows of pixels of interferogram， we simulate different interferograms with local bending of different local bending max offset， in different signal-to-noise ratio and modulation. The result shows that even local modulation is reduced when multiple rows of pixels of the distorted interferogram are merged， but the phase uncertainty of the interferogram will not increase. Therefore， even if the interferogram has defects， multiple rows of pixels can be merged to increase the signal-to-noise ratio and reduce the phase uncertainty. This article may provide a quantitative theoretical reference for the design， processing， and adjustment of the Doppler asymmetric spatial heterodyne. ? 2022 Chinese Optical Society. All rights reserved.Accession Number: 20224413027475 -
Record 242 of
Title:Research on focal length calibration method of oblique installation collimator
Author(s):Wang, Tao(1); Tian, Liude(1); Zhao, Jianke(1); Zhou, Yan(1); Kewei, E.(1); Liu, Kai(1); Liu, Shangkuo(1); Liu, Fei(2); Yang, Lihong(3); Liu, Yining(1); Xue, Xun(1); Zhao, Huaixue(1)Source: Hongwai yu Jiguang Gongcheng/Infrared and Laser Engineering Volume: 51 Issue: 11 DOI: 10.3788/IRLA20220124 Published: November 2022Abstract:When the collimator is placed horizontally and installed obliquely, its optical parameters will be greatly different due to different stress states. In order to accurately evaluate the focal length of collimator, according to the mapping relationship between the point on the focal plane of the collimator and the angle of the total station, an accurate mathematical model of the relationship between the focal length and the angle of the total station under the condition of oblique installation is established, the principle projection error caused by the rotation of the vertical axis of the total station is corrected. Several groups of data are collected by total station and experimental verification is carried out. After correcting the distortion, the focal length calculated by each testing point when the line segment is parallel to the vertical wire are 1 980.03 mm, 1 983.45 mm, 1 982.79 mm, the average focal length, i.e. the true value, is 1 982.09 mm. When the distortion is corrected but the projection error is not corrected, the focal length calculated from each testing point when the line segment is parallel to the horizontal wire of the reticle is 996.42 mm, 995.23 mm, 995.22 mm, the relative error of the average focal length is 50.2%. The range of focal length calculated by each testing point when the line segment is located in different quadrants and parallel to the horizontal wire of the reticle is 4.74 mm after correcting the projection error and distortion, the average focal length of all testing points is 1982.69 mm, the difference between the average value and the true value is 0.6 mm. The maximum relative error between the extended uncertainty of the focal length calculated by different testing point and the true value of the focal length is 0.36%. This value is far less than the stipulation in GB/T 9917.1-2002 that the relative error between the measured focal length and the nominal focal length in the photographic lens does not exceed ±5%. The experimental results show that the model has universality and high accuracy, the phase of the target slit in the reticle is allowed to be a random value, there is no need to adjust the slit to be strictly parallel to the vertical wire of the total station, the model has great engineering application value for the in-situ detection of the focal length of the collimator under the condition of oblique installation. ? 2022 Chinese Society of Astronautics. All rights reserved.Accession Number: 20225113257776 -
Record 243 of
Title:Mapping distortion correction in off-axis aspheric mirror testing with a null compensator
Author(s):Hao, Sanfeng(1,2); Zhang, Jian(1,3); Yang, Jianfeng(1); An, Fei(1)Source: Applied Optics Volume: 61 Issue: 14 DOI: 10.1364/AO.452951 Published: May 10, 2022Abstract:Mapping distortion can be introduced in null testing for off-axis aspheric surfaces, from which the testing results with coordinate deviation cannot be used to guide deterministic optical manufacturing. We propose a correction method for mapping distortion in this study based on the imaging distortion analysis of a null lens and iteration algorithm. We use imaging distortion data to fit the distortion polynomial function by the least-squares method, and we design an iteration algorithm to determine the rotation angle and the position of the null distortion point of the testing results. Finally, the mapping distortion can be accomplished without any markers on the mirror under test. The 280 mm × 180 mm primary mirror and 234 mm × 176 mm tertiary mirror of the hyperspectral camera were tested with a null compensator, and the distortion correction results were obtained using the proposed method. After magnetorheological finishing based on the correction results, the rms of the primary mirror and tertiary mirror reduced from 0.263 λ to 0.013 λ and 0.059 λ to 0.018 λ (λ = 632.8 nm), respectively. ? 2022 Optica Publishing Group.Accession Number: 20221912090588 -
Record 244 of
Title:Doppler Asymmetric Spatial Heterodyne Interferometry for Wind Measurement in Middle and Upper Atmosphere （Invited）
Author(s):Xiao, Yang(1,2); Feng, Yutao(1); Wen, Zhenqing(1,2); Fu, Di(1,2)Source: Guangzi Xuebao/Acta Photonica Sinica Volume: 51 Issue: 8 DOI: 10.3788/gzxb20225108.0851516 Published: August 2022Abstract:Atmospheric wind field is an important parameter to understand the dynamics and thermodynamic characteristics of the Earth's atmospheric system， and it is the basic data for weather forecasting， space environment monitoring， and climatology research. Passive optical remote sensing based on Optical interferometer is the main technical means of wind field measurement in the middle and upper atmosphere. In the 1960s， foreign research institutions began to use optical interferometers to detect upper atmospheric wind fields. and carried out the experimental research on interferometer payload technology simultaneously， and successively developed a series of representative scientific instruments and satellite payloads based on the Fabry-Pérot interferometer and the Wide Angle Michelson interferometer. In 2006， the ENGLERT C R research team of the U.S. Naval Research Laboratory proposed a new planetary atmospheric wind detection technology， called Doppler Asymmetric Spatial Heterodyne wind measurement technology， this technology detects the Doppler frequency shift of the atmospheric airglow spectrum by inverting the phase of the interferogram， thereby realizing the detection of the atmospheric wind field. Compared with the Fabry-Perot interferometer and the Wide-Angle Michelson interferometer， the Doppler Asymmetric Spatial Heterodyne interferometer has the following advantages： 1）Two-beam equivalent thickness spatial modulation interference， which relaxes the requirements for the optical index of the element； 2） Interferometer does not need Step-by-step scanning； 3） Wind speed inversion is based on the Fourier transform relationship between interferogram and spectrogram， so it does not need extremely narrow bandwidth （ ? 2022 Chinese Optical Society. All rights reserved.Accession Number: 20223912798032 -
Record 245 of
Title:Visual inspection system for battery screen print using joint method with multi-level block matching and K nearest neighbor algorithm
Author(s):Zhao, Zhuo(1); Li, Bing(1); Liu, Tongkun(1); Zhang, Shaojie(1); Lu, Jiasheng(1); Geng, Leqi(1); Cao, Jie(2)Source: Optik Volume: 250 Issue: DOI: 10.1016/j.ijleo.2021.168332 Published: January 2022Abstract:To overcome the drawbacks of manual quality inspection in battery industry, an online vision system is designed for battery screen print. Defect detection technique is based on the joint method of multi-level block matching and K nearest neighbor (KNN) algorithm. Firstly, execute preprocessing to origin images in segmentation, tilt correction and region cutting; Then create block templates on print area and train the corresponding models for active shape model (ASM) and KNN methods; Finally, coarse and accurate block matchings are applied to extract print defects in subsequent stages. In this period, KNN uses shape features of region components to recheck each target block. In addition, we adopt dynamic model updating mechanism to enhance system adaptability of condition changing. The joint method has two advantages: fault detection caused by print distortion is obviously reduced; accurate defect localization is also assured. Meanwhile, system hardware and software are also developed and calibrated to support detection method. Performance comparison, recognition rate and time efficiency are validated in experiment stage. It can be concluded that the proposed method has superior performances in both simulations and industrial application. ? 2021 Elsevier GmbHAccession Number: 20214811226199 -
Record 246 of
Title:Remote Sensing Cross-Modal Retrieval by Deep Image-Voice Hashing
Author(s):Zhang, Yichao(1,2); Zheng, Xiangtao(1); Lu, Xiaoqiang(1)Source: IEEE Journal of Selected Topics in Applied Earth Observations and Remote Sensing Volume: 15 Issue: DOI: 10.1109/JSTARS.2022.3216333 Published: 2022Abstract:Remote sensing image retrieval aims at searching remote sensing images of interest among immense volumes of remote sensing data, which is an enormous challenge. Direct use of voice for human-computer interaction is more convenient and intelligent. In this article, a deep image-voice hashing (DIVH) method is proposed for remote sensing image-voice retrieval. First, the whole framework is composed of the image and the voice feature learning subnetwork. Then, the hash code learning procedure will be leveraged in remote sensing image-voice retrieval to further improve the retrieval efficiency and reduce memory footprint. Hash code learning maps the deep features of images and voices into a common Hamming space. Finally, image-voice pairwise loss is proposed, which considers the similarity preservation and balance of hash codes. The similarity preserving and the balance controlling term of the loss function improve the similarity preservation from original data space to the Hamming space and the discrimination of binary code, respectively. This unified cross-modal feature and hash code learning framework significantly reduce the semantic gap between the two modal data. Experiments demonstrate that the proposed DIVH method can achieve a superior retrieval performance than other state-of-the-art remote sensing image-voice retrieval methods. ? 2008-2012 IEEE.Accession Number: 20224513093520 -
Record 247 of
Title:High-Precision Volume Measurement of Potholes in Pavement Maintenance
Author(s):Huang, Huimin(1); Zhou, Zuofeng(2); Liu, Mulong(3); Wu, Qingquan(2); Hu, Guoliang(1); Cao, Jianzhong(2)Source: Mathematical Problems in Engineering Volume: 2022 Issue: DOI: 10.1155/2022/9157849 Published: 2022Abstract:Accurate three-dimensional measurement of potholes is a significant concern in road maintenance. However, the assessment of road potholes still relies heavily on human inspectors to make maintenance suggestions. To realize full-field measurement of pavement pothole automatically, a high-precision volume measurement method based on second-order Taylor expansion is proposed, where the second-order Taylor estimation of each point is converted into a convolution operation. On the one hand, this method discards the second-order fitting of the surface, which greatly reduces the computational complexity. On the contrary, the second-order Taylor estimation is not restricted by the surface shape because it only depends on the distribution of the adjacent points. Experiments on synthesized and real point sets demonstrate that the proposed method outperforms the state-of-the-art methods under various point cloud shapes. ? 2022 Huimin Huang et al.Accession Number: 20222912363745 -
Record 248 of
Title:Reconstruction of Hadamard coded spectral data based on diffraction theory
Author(s):Liu, Wen-Long(1,2); Liu, Xue-Bin(1); Wang, Shuang(1); Yan, Qiang-Qiang(1)Source: Wuli Xuebao/Acta Physica Sinica Volume: 71 Issue: 9 DOI: 10.7498/aps.71.20211977 Published: May 5, 2022Abstract:Hardmard transfer imaging spectrometer (HTIS) is a novel computationally optical system. Its characteristic of multi-channel multiplexing increases the luminous flux of the optical system without sacrificing spatial resolution, thereby enabling the system's signal-to-noise ratio to be significantly higher than traditional spectrometer's. Encoding with digital mirror devices (DMD) in the system causes a serious diffraction effect that gives rise to the apparent degradation of the imaging formation. For improving the image quality and spectral accuracy of the reconstructed data cube, the Hadamard coded spectral imaging data degradation model is established based on the scalar diffraction theory. A data reconstruction algorithm is proposed based on the Lucy Richardson (L-R) algorithm. Through the simulation experiment, the process of image degradation is revealed. On the one hand, it proves that the degradation of system imaging diffraction is the main reason for the distortion of reconstructed data. On the other hand, it verifies the effectiveness of the correction method adopted in this paper. The evaluation result of the spectral angle distance of the restored data cube after L-R correction is 0.1296, and the image similarity evaluation factor is better than 0.85. Compared with the reconstructed data before being corrected, the corrected data is greatly improved in quality. The experimental results show that the algorithm has a good correction effect on the data cube reconstruction of HTIS. Copyright ? 2022 Acta Physica Sinica. All rights reserved.Accession Number: 20222112148946 -
Record 249 of
Title:Meta Self-Supervised Learning for Distribution Shifted Few-Shot Scene Classification
Author(s):Gong, Tengfei(1,2); Zheng, Xiangtao(1); Lu, Xiaoqiang(1)Source: IEEE Geoscience and Remote Sensing Letters Volume: 19 Issue: DOI: 10.1109/LGRS.2022.3174277 Published: 2022Abstract:Few-shot classification tries to recognize novel remote sensing image categories with a few shot samples. However, current methods assume that the test dataset shares the same domain with the labeled training dataset where prior knowledge is learned. It is infeasible to collect a training dataset for each domain, since remote sensing images may come from various domains. Exploiting the existing labeled dataset from another domain (source domain) to help the target dataset (target domain) classification would be efficient. In this letter, both meta-learning and self-supervised learning are jointly conducted for few-shot classification. Specifically, meta-learning is executed over a pretrained network for few-shot classification. Furthermore, self-supervised learning is exploited to fit the target domain distribution by training on unlabeled target domain images. Experiments are conducted on NWPU, EuroSAT and Merced datasets to validate the effectiveness. ? 2004-2012 IEEE.Accession Number: 20222012128358 -
Record 250 of
Title:A Novel Optical Frequency-Hopping Scheme Using Dual Drive Mach-Zehnder Modulator
Author(s):Jin, Ya(1); Chen, Shaokang(2); Xie, Zhuang(3); Zhai, Kunpeng(1); Xu, Changda(1); Wang, Jian(1); Chen, Yinfang(4); Wen, Huashun(4); Liu, Yu(4); Chen, Wei(4); Zhu, Ninghua(4)Source: IEEE Photonics Journal Volume: 14 Issue: 1 DOI: 10.1109/JPHOT.2021.3136856 Published: February 1, 2022Abstract:A novel optical frequency-hopping (OFH) scheme using dual-drive Mach-Zehnder modulator (DD-MZM) is proposed and demonstrated for secure transmission in fiber-optic networks. In the proposed scheme, by adjusting the phase difference between the radio frequency (RF) signals loaded on the two arms of the DD-MZM, and filtering the center carrier by fiber Bragg grating (FBG), thus the upper and lower output spectra can be realized randomly hop between the positive and negative first-order sidebands and serve as carriers for data modulation. And the data of different users are divided into many data slices in the time domain and then modulated to these carriers. To verify the feasibility of the proposed OFH scheme, we demonstrate an error-free transmission through 40 km fiber with 10 Gbps hopping rate and 10 Gbps data rate by simulation tools. In addition, we also establish a theoretical model to evaluate the security performance quantitatively, and the results show that the computing power required by illegal third parties to crack through brute force reaches 1.07 × 1027 calculations per second under certain conditions, which is almost impossible. Our OFH scheme has provided a deeper insight into physical layer security. ? 2009-2012 IEEE.Accession Number: 20220111425683 -
Record 251 of
Title:Spectral Super-Resolution of Multispectral Images Using Spatial–Spectral Residual Attention Network
Author(s):Zheng, Xiangtao(1); Chen, Wenjing(2,3); Lu, Xiaoqiang(4)Source: IEEE Transactions on Geoscience and Remote Sensing Volume: 60 Issue: DOI: 10.1109/TGRS.2021.3104476 Published: 2022Abstract:The spectral super-resolution of multispectral image (MSI) refers to improving the spectral resolution of the MSI to obtain the hyperspectral image (HSI). Most recent works are based on the sparse representation to unfold the MSI into the 2-D matrix in advance for subsequent operations, which results in that the spatial information of MSI cannot be fully explored. In this article, a spatial–spectral residual attention network (SSRAN) is proposed to simultaneously explore the spatial and spectral information of MSI for reconstructing the HSI. The proposed SSRAN is composed of the feature extraction part, the nonlinear mapping part, and the reconstruction part. Firstly, the multispectral features of the input MSI are extracted in the feature extraction part. Second, in the nonlinear mapping part, the spatial–spectral residual blocks are proposed to explore spatial and spectral information of MSI for mapping the multispectral features to the hyperspectral features. Finally, in the reconstruction part, a 2-D convolution is used to reconstruct the HSI from the hyperspectral features. Also, a neighboring spectral attention module is specially designed to explicitly constrain the reconstructed HSI to maintain the correlation among neighboring spectral bands. The proposed SSRAN outperforms the state-of-the-art methods on both simulated and real databases. ? 2021 IEEE.Accession Number: 20213410817489 -
Record 252 of
Title:High power laser incoherent spatial beam combining with rectangular spot
Author(s):Wang, Yi(1,2); Lei, Guangzhi(3); Yu, Lidong(1,2); Zha, Rongwei(1,2); Zhou, Jingfeng(1,2); Bai, Yang(1,2)Source: Hongwai yu Jiguang Gongcheng/Infrared and Laser Engineering Volume: 51 Issue: 4 DOI: 10.3788/IRLA20210268 Published: April 25, 2022Abstract:This work lays a foundation for promoting the application of incoherent spatial combining laser in laser surface heat treatment with high speed and flexible processing. 18 semiconductor laser beams at 972 nm output by the fiber were arranged in parallel according to the "matrix". By implementing beam collimation and incoherent spatial beam combination, a 10 kW combined laser beam with rectangular spot characteristics was obtained. The radius of the collimated laser beam, the distance between adjacent laser beams and the overlapping rate of the combined laser were theoretically analyzed, respectively. The structural model of the beam combiner was built using Code V software, and the spot energy distribution of the combined laser was simulated using TracePro software. Based on the above work, a 10 kW 18×1 incoherent spatial laser combiner of outputting a rectangular spot was developed. Within the combined length of 200 mm, the combined laser beam had a single rectangular spot shape. A beam combining power of 10.249 kW was achieved with a focal spot diameter of 31 mm×11 mm, a center wavelength of 972.34 nm and a linewidth of 2.27 nm. Copyright ?2022 Infrared and Laser Engineering. All rights reserved.Accession Number: 20221912084165