2022
2022
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Record 301 of
Title:SAR Object Detection Encounters Deformed Complex Scenes and Aliased Scattered Power Distribution
Author(s):Zhang, Yawei(1); Cao, Yu(2,3,4); Feng, Xubin(5); Xie, Meilin(5); Li, Xin(1); Xue, Yao(1); Qian, Xueming(6)Source: IEEE Journal of Selected Topics in Applied Earth Observations and Remote Sensing Volume: 15 Issue: DOI: 10.1109/JSTARS.2022.3157749 Published: 2022Abstract:Synthetic aperture radar (SAR) is widely used in terrain classification, object detection, and other fields. Compared with anchor-based detectors, anchor-free detectors remove the anchor mechanism and implement detection box encoding in a more elegant form. However, anchor-free detectors are limited by complex scenes caused by geometric transformations, such as overlaying, shadow, vertex displacement during SAR imaging. And the scattered power distribution of noise is similar to the edge of the object, making it difficult for the detector to locate the edge of the SAR object accurately. In order to alleviate these problems, we propose a high-speed and high-performance SAR image anchor-free detector. First, we propose a shallow feature refinement (SFR) module to effectively extract and retain the detailed information of objects, while coping with deformed complex scenes. Second, we analyze the optimization focus of the detector at different training iterations and propose iteration-aware loss to guide the detector, making the detector more accurately locate the edge of the object disturbed by the noise scattered power distribution. Third, number estimation helps to detect objects with more flexible criteria in box selection without manual labor. Compared with mainstream optical object detectors and SAR dedicated detectors, our method achieves the best speed-accuracy tradeoff on the SAR-ship dataset, with 96.4% average precision when the value of intersection over union is 50% (AP_{50}) at 64.9 frames per second. The experimental results prove the effectiveness of our method. ? 2008-2012 IEEE.Accession Number: 20221111799465 -
Record 302 of
Title:Phase retrieval algorithms: principles, developments and applications (invited)
Author(s):Wang, Aiye(1,2,3); Pan, An(1,2); Ma, Caiwen(1,2,3); Yao, Baoli(1,2)Source: Hongwai yu Jiguang Gongcheng/Infrared and Laser Engineering Volume: 51 Issue: 11 DOI: 10.3788/IRLA20220402 Published: November 2022Abstract:Because the phase contains more information about the field in contrast to the amplitude, phase measurement has always been a hot topic in many branches of modern science and engineering. Within the visible range of electromagnetic wave, it is quite difficult to directly obtain phase information by the existing photodetectors. Phase retrieval provides an effective method to "figure out" the phase information from the captured intensity information, and has achieved successful applications in several scientific fields including astronomical observation, biomedical imaging and digital signal restoration. Algorithm is not only the core of phase retrieval, but is also the key to its development and applications. This paper demonstrates the basic principles of phase retrieval algorithms in combination with physical principles and signal processing methods, summarizes the development of various kinds of algorithms as well as their advantages and disadvantages, and briefly lists some typical applications in the field of optics. Finally, the challenges are pointed out, and the future development directions are described as: better convergence performance and noise robustness, phase-retrieval ability for more complex objects, compatibility for integration of multiple objectives and tasks. ? 2022 Chinese Society of Astronautics. All rights reserved.Accession Number: 20225113262617 -
Record 303 of
Title:Experimental Study on the Spatial Performance of Photorefractive X-ray Semiconductor Ultrafast Response Chip
Author(s):Tan, Xiaobo(1); Yan, Xin(2); Yi, Tao(3); He, Kai(2); Shao, Zhengzheng(1); Zhou, Kaikai(1); Gao, Guilong(2); Wang, Tao(2); Zhang, Jun(1); Zhuang, Zhaowen(1)Source: Guangzi Xuebao/Acta Photonica Sinica Volume: 51 Issue: 2 DOI: 10.3788/gzxb20225102.0251215 Published: February 25, 2022Abstract:The traditional ultrafast electric vacuum devices are usually based on the mechanism of photoelectric conversion, and their performance is restricted by factors such as material response and space-charge effect. It is difficult for the devices like microchannel plate framing cameras, DIlation X-ray Imager (DIXI), streak cameras to achieve high temporal resolution (100 fs~1 ps) and spatial resolution (~μm) two-dimensional imaging. Ultrafast imaging technology based on photorefractive effect is a new ultrafast diagnostic technology, which has the advantages of high spatiotemporal resolution, all-optical, all-solid-state, and anti-radiation. The nonequilibrium carrier lifetime of low-temperature grown AlGaAs (LT-AlGaAs) can reach ps-level. The Ultrafast Response Chip (URC) made of LT-AlGaAs has the characteristics of high temporal resolution, meanwhile, good spatial performance is the other key factor for its application. In this paper, the spatial performance of LT-AlGaAs URC is experimentally studied using X-ray, generated by high-energy nanosecond pulsed laser-produced plasma, as the signal. The results show that the URC has the ability of high spatial resolution and large-scale imaging in the X-ray energy dynamic range of 120:1. The optimal spatial resolution is ≥ 35 lp/mm @ MTF = 0.1, and the imaging frame can reach 6.7 mm × 6.7 mm. The results further verify the feasibility of ultrafast diagnostic technology based on photorefractive materials. In the future, LT-AlGaAs URC will be combined with ultrafast framing technologies such as dispersion framing and polarization chirp framing to realize multi-frames and high spatiotemporal resolution two-dimensional imaging. ? 2022, Science Press. All right reserved.Accession Number: 20221311863500 -
Record 304 of
Title:Enhancement of the radiation resistance of cerium-containing fluorophosphate glasses through codoping with Sb2O3 and Bi2O3
Author(s):Zhang, Faqiang(1,2); Cao, Xin(1,2); Ma, Yuan(1,2); Zhang, Zhijun(1); Huo, Weirong(3); Wan, Rui(1,2); Yang, Liqing(1); Gao, Fei(1); Wang, Pengfei(1,2)Source: Ceramics International Volume: 48 Issue: 14 DOI: 10.1016/j.ceramint.2022.03.280 Published: July 15, 2022Abstract:The growing demand for radiation-resistant optical glasses for space and nuclear radiation applications has attracted significant research interest. However, radiation-resistant fluorophosphate glasses have been poorly studied. In this work, we report on the tailoring and performance of radiation-resistant fluorophosphate glasses that contained cerium through codoping with Sb2O3 and Bi2O3. The physical properties, optical properties, microstructure, and defects of fluorophosphate glasses were investigated using transmittance measurements, absorption measurements, as well as Raman spectroscopy, X-ray photoelectron spectroscopy (XPS), and electron paramagnetic resonance (EPR) spectroscopy. The results showed that the radiation resistance of all codoped fluorophosphate glasses was better than the undoped cerium-containing fluorophosphate glasses after 10–250 krad(Si) irradiation. Especially in glasses doped with Bi2O3, the optical density increment at 385 nm was only 0.1482 after 250 krad(Si) irradiation. The CeO2 prevented the development of phosphate-related oxygen hole center (POHC) defects, whereas further codoping with Bi2O3 suppressed the formation of oxygen hole center (OHC) and POEC defects, reducing the breaking of phosphate chains caused by CeO2. Bi3+ is more likely than Sb3+ to change the valence, affecting the transition equilibrium of intrinsic defects and reducing the concentration of defects produced by irradiation. When codoping with Sb2O3 and Bi2O3, Bi2O3 does not enhance radiation resistance owing to the scission effect of Sb2O3 on the phosphate chain, which is not conducive to the radiation resistance of glasses. This indicates that the cerium-containing fluorophosphate glasses doped with Bi2O3 can effectively suppress the defects caused by irradiation and improve the radiation resistance of the glasses. ? 2022 Elsevier Ltd and Techna Group S.r.l.Accession Number: 20221511947080 -
Record 305 of
Title:Performance evaluation of silicon-chip-based mid-infrared Kerr optical frequency combs with ridge cross section
Author(s):Wen, Jin(1,2,3,4); Qin, Weijun(2); Sun, Wei(2); He, Chenyao(2); Xiong, Keyu(2); Liang, Bozhi(2)Source: Optik Volume: 266 Issue: DOI: 10.1016/j.ijleo.2022.169575 Published: September 2022Abstract:We present a complementary metal-oxide-semiconductor (CMOS) compatible platform for on-chip frequency comb generation in the mid-infrared region based on a silicon-on-insulator (SOI) microring resonator with ridge cross section. Flat dispersion tailoring is performed with dispersion variation of 4.04 × 10?6 ps/nm/km by adjusting the geometry parameter and the low-loss SOI microring resonator with total quality factor (Q) up to 106 can be realized at wavelengths from 3.3 to 3.6 μm. Furthermore, the thresholdless frequency combs consisting of 50 comb lines spanning from 3.1 to 4.0 μm (over 900 nm) can be realized using SOI microring resonator with 50 mW pump power. Besides, the study shows that the frequency interval of the comb is related to the selection of the dual-pumped wavelength. The influences of the coupling coefficient and the radius of microring on the bandwidth of mid-infrared OFC are also investigated numerically which shows that remarkable enhancement of mid-infrared OFC bandwidth can reach 449 nm when the coupling coefficient varies from 0.012 to 0.05. This research work is instructive for realizing highly integrated photonics and achieving the experimental generation of mid-infrared optical frequency combs, which could enable substantial progress in spectroscopy applications. ? 2022 Elsevier GmbHAccession Number: 20222712329921 -
Record 306 of
Title:Design of Large Depth Field Photon Doppler Velocimeter and Application in Ultra-high Speed Interior Ballistic Research
Author(s):Hao, Geyang(1,2); Luo, Qing(3); Yang, Yahan(4); Yan, Zhaochao(4); Wu, Guojun(1); Huang, Jie(3)Source: Guangzi Xuebao/Acta Photonica Sinica Volume: 51 Issue: 6 DOI: 10.3788/gzxb20225106.0628002 Published: June 1, 2022Abstract:The Photon Doppler Velocimeter （PDV） is a non-contact velocity measurement equipment with high accuracy and high-time resolution， which can obtain the continuous interior ballistic velocity of ultra-high-speed launchers. Continuous velocity data is very important for ultra-high-speed experiments. It can be used to understand the performance of ultra-high-speed launchers and the physical processes of ultra-high-speed， as well as to develop the theory of interior ballistics. Limited by the small size of the muzzle， the serious attenuation of laser energy and （the limitation of） the bandwidth of detector， it is difficult for ordinary PDV to obtain continuous ultra-high-speed interior ballistic velocity. In this paper， we have developed a large depth field PDV with an effective working distance greater than 7 m， which is constructed based on fiber Mach-Zehnder interferometer. The emission aperture of optical antenna is 25 mm， the beam waist of emission position is located at 3.3~3.4 m， and the diameter of beam waist is 1 245 mm. In order to verify the performance of the system， we first simulated the high-speed motion process by using a rotating turntable and a motor， and tested the measurement error of the PDV system. In the velocity range of 1~40 m/s， the measurement uncertainty of the PDV can be controlled at 2.48%. Then we carried out experiments on the ultra-high-speed ballistic target （FD-18A） of China Aerodynamics Research and Development Center （CARDC）， and repeatedly obtained the continuous ultra-high-speed inner ballistic velocity of the ultra-high-speed two-stage light gas guns. In the experiments， we placed a reflector directly behind the muzzle to change the direction of the laser signal and put the optical antenna on one side of the reflector. Finally， the PDV recorded the velocity changes of the launch model from static acceleration to about 2 km/s and 7 km/s， with the maximum velocity of 6.89 km/s. By comparing with the numerical simulation results， it is found that the measured velocity of experiment is lower than the simulation velocity in the test with a velocity of 2 km/s. While the measured velocity of experiment is higher than the simulation speed in the test with a velocity of 7 km/s， and the deviations are -20.11%， -23.7% and +9.15%， respectively. Through the analysis of velocity-acceleration data， it is found that the difference in friction between simulation and experiment may be the main reason for the difference of velocity. The actual friction force of the ultra-high-speed projectile in the ballistic target is greater than the theoretical friction force given in the simulation， so it may cause that the maximum speeds and accelerations are lower than the theoretical results in the test with an estimated launch velocity of 2 km/s. In the test with a velocity of 7 km/s， the mass of the projectile decreases rapidly due to severe friction， so the maximum velocity and acceleration in the second half of the movement are gradually larger than the simulation results. ? 2022 Chinese Optical Society. All rights reserved.Accession Number: 20224413027528 -
Record 307 of
Title:Tracking Performance Detection Technology of Optical Measuring Equipment Based on Moving Platform
Author(s):Li, Xiyu(1); Gao, Xin(1); Sun, Liangliang(1); Lei, Chengqiang(1); Shi, Heng(1,2,3,4); Hu, Lei(1); Zong, Yonghong(1); Zheng, Donghao(1)Source: Guangzi Xuebao/Acta Photonica Sinica Volume: 51 Issue: 12 DOI: 10.3788/gzxb20225112.1212002 Published: 2022Abstract:The optical measurement equipment has gradually expanded from ground-based to ship-borne，vehicle-mounted，and airborne platforms. At this stage，the traditional ground-based single axis dynamic detection device is used to detect the tracking performance of the optical measurement equipment with the moving platform，and its motion trajectory is relatively single. The motion equation components of the simulated target in the azimuth and pitch directions have high-order derivatives. Although the axis number for the detection target has been increased to three，there are still position blind spots in the workspace. It is impossible to truly simulate the 6-DOF（Degree of Freedom）motion characteristics of moving platform and typical maneuvering target.In order to test and evaluate the tracking performance of optical measuring equipment with a moving platform under ground conditions，a 6-DOF detection target and detection method are proposed. In view of the fact that the traditional kinematics modeling and trajectory planning methods of multi-DOF serial mechanisms need to establish six coordinate systems，the calculation process is cumbersome，and there are problems such as poor real-time performance and easy to appear motion singular solutions. A continuous and singularity free kinematic model of the detection target is established in a global way by using the screw exponential product method. The method only needs to establish the head and tail coordinate systems of the detection target，which can completely express the transformation relationship between joints，and it is convenient to solve the inverse kinematics. The fusion motion trajectory in real time and high precision is simulated and the operation efficiency is improved. Shipborne optical measuring equipment is a typical ship moving platform equipment. The XX-1109 shipborne optical measuring equipment is studied and its tracking performance is tested.According to the performance of the detection target and optical measurement equipment，the azimuth and pitch axes tracking random errors of the XX-1109 shipborne optical measurement equipment are calculated and analyzed to be 23.88″and 23.86″，respectively. The simulated optical target is installed at the end of the 6-DOF manipulator，and then a new 6-DOF detection system is constructed. The detection system is mainly composed of the simulated optical target， 6-DOF manipulator， operation control subsystem， data communication subsystem，time measurement terminal and data processing subsystem. The detection target adopts ABB 6-DOF manipulator IRB 6700-205，and its repeated positioning accuracy is 0.1 mm. The XX-1109 shipborne optical measurement equipment is deployed at a distance of about 5 meters from the detection target. The detection target simulates the movement track in real time. The XX-1109 tracks the simulated target in real time to achieve the detection and identification of tracking performance. By formulating a reasonable and feasible detection method，the tracking performance of XX-1109 optical measurement equipment is tested and evaluated. The test results show that the kinematics model of the detection target established by the screw exponential product method realizes the real-time high-precision trajectory planning of the ship moving platform and typical maneuvering targets，which improves the calculation efficiency and avoids the problem of motion singularity in traditional modeling methods. Considering the size of angular velocity and the randomness of error，the tracking random error of the XX-1109 optical measuring equipment is consistent with the theoretical analysis，which verifies the effectiveness and superiority of the new detection system and method. The tracking performance test of the optical measuring equipment with moving platform under the ground conditions is realized. The new detection system and method have successfully completed the detection and identification of the optical measurement equipment on shipborne，vehicle-mounted and airborne moving platforms. It can not only quickly find tracking performance problems in the development stage，but also reduce the development cycle and the cost，which has important engineering application value. ? 2022 Chinese Optical Society. All rights reserved.Accession Number: 20230813622792 -
Record 308 of
Title:Frequency Control of Laser Cavity Solitons for Metrological Applications
Author(s):Cutrona, Antonio(1); Rowley, Maxwell(1); Bendahmane, Abdelkrim(1); Hanzard, Pierre-Henry(1); Peters, Luke(1); Cecconi, Vittorio(1); Olivieri, Luana(1); Little, Brent E.(2); Chu, Sai T.(3); Morandotti, Roberto(4); Moss, David J.(5); Totero-Gongora, Juan Sebastian(1); Peccianti, Marco(1); Pasquazi, Alessia(1)Source: Optics InfoBase Conference Papers Volume: Issue: DOI: Published: 2022Abstract:We show the free-running frequency stability and the frequency control of a micro-comb system comprising a micro-ring nested into an amplifying fibre cavity. ? Optica Publishing Group 2022.Accession Number: 20230413452163 -
Record 309 of
Title:Development and Prospect of Stray Light Suppression and Evaluation Technology（Invited）
Author(s):Wang, Hu(1,2,3); Chen, Qinfang(1); Ma, Zhanpeng(1,2); Yan, Haoyu(1,2); Lin, Shangmin(1,2); Xue, Yaoke(1,4,5)Source: Guangzi Xuebao/Acta Photonica Sinica Volume: 51 Issue: 7 DOI: 10.3788/gzxb20225107.0751406 Published: July 2022Abstract:With the rapid development of space optical technology and the continuous improvement of the performance of photoelectric detection devices， remote sensing systems with high resolution，multispectral，and low detection threshold are more and more widely used in aviation，aerospace and other fields. And the capabilities and evaluation indicators for the stray light suppression of electric-optic load are gradually becoming stricter. The stray light suppression technology and simulation analysis has become one of the indispensable links. Although the domestic stray light suppression and evaluation technology have developed earlier，a systematic method is still needed to lead the development of this technology to change the current research status of decentralization and fragmentation. Therefore，it is necessary to establish an integrated stray light suppression and evaluation method system，and conduct in-depth research in four key technical modules，including the formulation of stray light suppression scheme，suppression model surface characteristic measurement and modeling，stray light suppression effect simulation，and stray light test and evaluation and so on. Based on the theory of stray light radiation transfer，we give the corresponding suppression methods according to the stray light inside and outside the field of view，and the internal thermal radiation stray light. But the actual stray light sources are complex and in various forms，often requiring various suppression methods together，such as selecting the configuration of the optical system，setting the baffle and vanes，adding the stops，coating the optical surface，and blackening the surface of the structural parts. In addition，in some specific cases，filtering method，adjacent frame subtraction method，polarization method，numerical aperture method，and image correction method can also be used to suppress stray light. Opto-mechanical systems are generally composed of various surfaces with different materials and properties and they have different characteristics such as reflection，scattering，and absorption. Therefore，studying the surface characteristics of the system is the basis for stray light analysis. The measurement of surface properties can be used as a preliminary method to obtain the surface information of the material. On this basis，modeling calculations can be performed to make up for the deficiency that the experimental measurement cannot obtain any direction of incidence and observation. It can be widely promoted and applied in engineering. Computer simulation is an important means of stray light analysis，which can solve the problems of too cumbersome and high testing costs for stray light experiments in optical systems with high suppression ratios，and improve the efficiency of stray light analysis. The Monte Carlo method has been widely used in a variety of commercial software due to its high accuracy and computational simplicity.With the rapid development of computer technology and the emergence of new algorithms，the number，speed，and accuracy of ray tracing will be improved. It can more accurately simulate the influence of stray light on the whole system. Stray light measurement is the key to the final determination and verification of the system’s true stray light suppression capability. The measurement methods of stray light have formed two evaluation methods. The veiling glare index is suitable for general optical systems with low precision and small aperture，and the point source transmittance method is suitable for optical systems with large aperture and high stray light suppression ratio requirements. Xi’an Institute of Optics and Precision Mechanism of the Chinese Academy of Sciences has developed the first domestic point source transmittance stray light test device with the strongest capability of testing. It has been successfully applied to the stray light measurement of space equipped with high accuracy and served many scientific institutes and universities. This paper gives a set of the overall technical route and provides the idea for better promoting the development and application of stray light suppression and evaluation technology. ? 2022 Chinese Optical Society. All rights reserved.Accession Number: 20223612692465 -
Record 310 of
Title:Small Infrared Target Detection Based on Fast Adaptive Masking and Scaling with Iterative Segmentation
Author(s):Chen, Yaohong(1,4,5); Zhang, Gaopeng(1); Ma, Yingjun(1); Kang, Jin U.(2); Kwan, Chiman(3)Source: IEEE Geoscience and Remote Sensing Letters Volume: 19 Issue: DOI: 10.1109/LGRS.2020.3047524 Published: 2022Abstract:Fast and robust small infrared (IR) target detection is a challenging task and critical to the performance of IR searching and tracking (IRST) systems. However, the current algorithms generally have difficulty in striking a good balance between speed and performance. In this letter, we propose a new approach to small IR target detection that can significantly accelerate the detection process by first performing a fast adaptive masking and scaling algorithm. We then propose to enhance the target characteristics and suppress the background clutter using both contrast and gradient information. Finally, we propose to accurately extract the targets via iterative segmentation. The experimental results demonstrated that our proposed method yields the best and the most robust performance, with a speed of at least two times faster than the state-of-the-art methods. ? 2004-2012 IEEE.Accession Number: 20210409830531 -
Record 311 of
Title:Context and Difference Enhancement Network for Change Detection
Author(s):Song, Dawei(1,2); Dong, Yongsheng(3,4); Li, Xuelong(3,4)Source: IEEE Journal of Selected Topics in Applied Earth Observations and Remote Sensing Volume: 15 Issue: DOI: 10.1109/JSTARS.2022.3217082 Published: 2022Abstract:At present, convolution neural networks have achieved good performance in remote sensing image change detection. However, due to the locality of convolution, these methods are difficult to capture the global context relationships among different-level features. To alleviate this issue, we propose a context and difference enhancement network (CDENet) for change detection, which can strongly model global context relationships and enhance the change difference. Specifically, our backbone is the dual TransUNet, which is based on U-Net and equipped with transformer block in the encoder. The dual TransUNet is used to extract bitemporal features. Then, the features are encoded as the input sequence, which is conducive to modeling the global context. Moreover, we design the content difference enhancement module to process the dual features of each layer in the encoder. The designed module can increase the spatial attention of difference regions to enhance the change difference features. In the decoder, we adopt a simple cross-layer feature fusion to combine the upsampled features with the high-resolution features, which is used to generate more accurate results. Finally, we adopt a novel loss to supervise the accuracy of results in regions and pixels. The experiments on two public change detection datasets demonstrate that our CDENet has strong competitiveness and performs better than the state-of-the-art methods. ? 2008-2012 IEEE.Accession Number: 20224513093567 -
Record 312 of
Title:Tailoring high-performance illumination lenses for extended non-Lambertian sources
Author(s):Ding, Zhanghao(1); Shen, Fanqi(1); Liu, Yingli(1); Kuang, Cuifang(1); Zheng, Zhenrong(1); Jia, Shengnan(2); Cao, Liping(2); Mao, Xianglong(3); Wu, Rengmao(1)Source: Applied Optics Volume: 61 Issue: 20 DOI: 10.1364/AO.461962 Published: July 10, 2022Abstract:A key challenge in tailoring compact and high-performance illumination lenses for extended non-Lambertian sources is to take both the étendue and the radiance distribution of an extended non-Lambertian source into account when redirecting the light rays from the source. We develop a direct method to tailor high-performance illumination lenses with prescribed irradiance properties for extended non-Lambertian sources. A relationship between the irradiance distribution on a given observation plane and the radiance distribution of the non- Lambertian source is established. Both edge rays and internal rays emanating from the extended light source are considered in the numerical calculation of lens profiles. Three examples are given to illustrate the effectiveness and characteristics of the proposed method. The results show that the proposed method can yield compact and high-performance illumination systems in both the near field and far field. ?2022 Optica Publishing GroupAccession Number: 20222812339250