2022
2022
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Record 193 of
Title:Efficient dispersion engineering for three-octave-spanning supercontinuum generation in nanophotonic waveguides
Author(s):Liu, Mulong(1); Gu, Chengwei(2); Fan, Xuening(1); Li, Zhiheng(1); Huang, Huimin(3); Lu, Zhizhou(4); Zhao, Wei(5)Source: Optics and Laser Technology Volume: 150 Issue: DOI: 10.1016/j.optlastec.2022.107923 Published: June 2022Abstract:We propose a dispersion-flattened technology for producing broadband and low anomalous dispersion with minimal zero-dispersion wavelengths (ZDWs). This structure can be formed by nanophotonic waveguides using different material combinations. Flat dispersion varying between 0 and 27 ps/nm/km and spanning a range of wavelengths between 1290 and 4570 nm can be achieved. Without applying dispersion hybridization and using complex material combinations, dispersion demonstrates good tolerance to pump wavelength selection and is easier to introduce. Furthermore, the designed structures are applied to generate a supercontinuum over three octaves considering wavelength dependent loss from cladding, which exhibits an excellent bandwidth of ? 40 dB even with increasing losses from the waveguide material or structure generation. These findings are useful for supercontinuum generation over multiple octaves in different platforms, which is promising for self-referenced f-2f systems and spectroscopy applications. ? 2022 Elsevier LtdAccession Number: 20220711631533 -
Record 194 of
Title:Mutual Attention Inception Network for Remote Sensing Visual Question Answering
Author(s):Zheng, Xiangtao(1); Wang, Binqiang(1); Du, Xingqian(1); Lu, Xiaoqiang(1)Source: IEEE Transactions on Geoscience and Remote Sensing Volume: 60 Issue: DOI: 10.1109/TGRS.2021.3079918 Published: 2022Abstract:Remote sensing images (RSIs) containing various ground objects have been applied in many fields. To make semantic understanding of RSIs objective and interactive, the task remote sensing visual question answering (VQA) has appeared. Given an RSI, the goal of remote sensing VQA is to make an intelligent agent answer a question about the remote sensing scene. Existing remote sensing VQA methods utilized a nonspatial fusion strategy to fuse the image features and question features, which ignores the spatial information of images and word-level information of questions. A novel method is proposed to complete the task considering these two aspects. First, convolutional features of the image are included to represent spatial information, and the word vectors of questions are adopted to present semantic word information. Second, attention mechanism and bilinear technique are introduced to enhance the feature considering the alignments between spatial positions and words. Finally, a fully connected layer with softmax is utilized to output an answer from the perspective of the multiclass classification task. To benchmark this task, a RSIVQA dataset is introduced in this article. For each of more than 37 000 RSIs, the proposed dataset contains at least one or more questions, plus corresponding answers. Experimental results demonstrate that the proposed method can capture the alignments between images and questions. The code and dataset are available at https://github.com/spectralpublic/RSIVQA. ? 1980-2012 IEEE.Accession Number: 20212310473040 -
Record 195 of
Title:Sea-Urchin-MnO2 for Broadband Optical Modulator
Author(s):Han, Yueheng(1); Li, Xiaohui(1); Chen, Enci(2); An, Mingqi(1); Song, Zhuoying(3); Huang, Xiangzhen(1); Liu, Xinfeng(4); Wang, Yishan(5); Zhao, Wei(5)Source: Advanced Optical Materials Volume: 10 Issue: 22 DOI: 10.1002/adom.202201034 Published: November 18, 2022Abstract:Manganese dioxide (MnO2) is considered to be one of the nanomaterials with enormous value in research and application because of its high theoretical specific capacitance, large specific surface area and porosity, excellent electron transfer ability, and excellent light absorption ability. However, exploring superior nonlinear absorption of MnO2 in the broadband spectrum is still the key challenge to harvesting their greatest potential. In this paper, the optical modulator based on MnO2 is fabricated, and its nonlinear optical performance is measured. The results indicate that the modulation depth is 4.4% and the saturable intensity is 32.8 MW?cm?2 at 1.5?μm region. What's more fascinating is that the modulator based on MnO2 is integrated into Er-doped and Tm-doped fiber resonators to successfully demonstrate its broadband mode-locking operations. The coexistence of harmonic bound state pulse and conventional soliton pulse, as well as dual-wavelength solitons, have been obtained in a communication window and conventional soliton in a 2?μm-band can be also achieved. This demonstrates that MnO2 serves as a broadband optical modulator, which makes MnO2 more competitive in the future ultrafast photonics and helps to expand the frontier of photonic technology. ? 2022 Wiley-VCH GmbH.Accession Number: 20223612684671 -
Record 196 of
Title:Unsupervised Change Detection by Cross-Resolution Difference Learning
Author(s):Zheng, Xiangtao(1); Chen, Xiumei(1); Lu, Xiaoqiang(1); Sun, Bangyong(1)Source: IEEE Transactions on Geoscience and Remote Sensing Volume: 60 Issue: DOI: 10.1109/TGRS.2021.3079907 Published: 2022Abstract:Change detection (CD) aims to identify the differences between multitemporal images acquired over the same geographical area at different times. With the advantages of requiring no cumbersome labeled change information, unsupervised CD has attracted extensive attention of researchers. Multitemporal images tend to have different resolutions as they are usually captured at different times with different sensor properties. It is difficult to directly obtain one pixelwise change map for two images with different resolutions, so current methods usually resize multitemporal images to a unified size. However, resizing operations change the original information of pixels, which limits the final CD performance. This article aims to detect changes from multitemporal images in the originally different resolutions without resizing operations. To achieve this, a cross-resolution difference learning method is proposed. Specifically, two cross-resolution pixelwise difference maps are generated for the two different resolution images and fused to produce the final change map. First, the two input images are segmented into individual homogeneous regions separately due to different resolutions. Second, each pixelwise difference map is produced according to two measure distances, the mutual information distance and the deep feature distance, between image regions in which the pixel lies. Third, the final binary change map is generated by fusing and binarizing the two cross-resolution difference maps. Extensive experiments on four datasets demonstrate the effectiveness of the proposed method for detecting changes from different resolution images. ? 1980-2012 IEEE.Accession Number: 20212310473922 -
Record 197 of
Title:Optical Design of Optical Passive Half-Athermalization Zoom Lens with High Zoom Ratio
Author(s):Yan, Aqi(1); Cui, Wen(1,2); Dong, Sen(1)Source: Guangxue Xuebao/Acta Optica Sinica Volume: 42 Issue: 4 DOI: 10.3788/AOS202242.0422001 Published: February 25, 2022Abstract:In view of traditional zoom lens cannot consistently and clearly image during the whole zoom process when the ambient temperature is changed, which needs to focus frequently at middle focal length position. This paper proposes a new design method which is named optical passive half-athermalization zoom lens design, and an optical passive half-athermalization zoom lens is designed by this novel method. The focal length of zoom lens is 301000 mm, spectrum wavelength is 486656 nm, and F-number is F4.4F8. Most importantly, the shortest focal length position of zoom lens is optical passive athermalization. The optical system has compact structure and excellent imaging quality, and based on method of passive half-athermalization design, optical system at any temperature between -40 ℃ and +60 ℃, which only need to focus once at the longest focal length position of zoom lens, that can ensure consistently and clearly image during the whole zoom process. There is no need to focus frequently in any middle zoom position, and the temperature adjustment of zoom lens is only -0.56+0.82 mm, which have verified method of optical passive half-athermalization zoom lens design correctly. According to this method, zoom lens not only overcomes trouble of frequently focusing in traditional zoom lens, but also greatly reduces amount of temperature focusing and benefits on fast focusing. ? 2022, Chinese Lasers Press. All right reserved.Accession Number: 20221211831521 -
Record 198 of
Title:Development of a large-field streak tube for underwater imaging lidar
Author(s):Fang, Mengyan(1,2); Xue, Yanhua(1); Ji, Chao(1,2); Yang, Bingqing(1); Xu, Guoquan(3); Chen, Fubin(3); Li, Guangying(1,2); Han, Wenjie(4); Xu, Ke(3); Cheng, Guanghua(5); Li, Shaohui(1); Wang, Junfeng(1); Liu, Baiyu(1); Zhao, Wei(1,2,6); Tian, Jinshou(1,2,6); Wang, Xing(1,2)Source: Applied Optics Volume: 61 Issue: 25 DOI: 10.1364/AO.464643 Published: September 1, 2022Abstract:Streak tube imaging lidar (STIL) can obtain 4-D images of a target, and its performance is mainly determined by the streak tube sensor. To obtain a large field of view, we developed a streak tube with a photocathode length as large as 35.3mm, which is larger than the commonly used ST-HDR(30 mm). At the same time, the temporal resolution and dynamic spatial resolution are 60 ps and 12 lp/mm, which are very suitable to obtain accurate target coordinates for 4-D imaging. In addition, the streak tube has a high detection sensitivity of 46 mA/W at 500 nm and, hence, prospects in remote imaging. To test the performance of the streak tube, an underwater STIL experiment was conducted. Echo signal processing was performed by means of a bandpass filter and a matched filter, and then the peak detection algorithm was used to reconstruct the image. The results indicate that a spatial resolution better than 9 mm is achieved in the limpid water with a depth of 20 m, and a range accuracy of 1 cm is achieved in the turbid water with a depth of 10 m. Such a performance suggests that the large-field streak tube is of great potential for underwater target imaging and other remote imaging applications. ?2022 Optica Publishing Group.Accession Number: 20223612686016 -
Record 199 of
Title:Research on Automatic Cutting Method of Oil Cone Sleeve Sample
Author(s):Xiaolei, Liu(1); Jie, Zhang(1); Wenhui, Fan(2)Source: Proceedings - 2022 37th Youth Academic Annual Conference of Chinese Association of Automation, YAC 2022 Volume: Issue: DOI: 10.1109/YAC57282.2022.10023888 Published: 2022Abstract:Modern aerial refueling aircraft and its aerial refueling technology have become an important measure to enhance the mobility and strike capability of aviation forces, and are highly valued by countries all over the world. With the continuous development of computer image and machine learning, it is possible to locate and identify the refueling cone sleeve in real time in the process of aerial refueling docking. At present, the mainstream method is target recognition based on deep learning, but the premise of deep learning is to cut a large number of data samples. Aiming at the problem that deep learning requires a lot of manpower and energy to cut training samples, this paper proposes an automatic cutting method of cone sleeve training samples based on the combination of color features and circular features to realize the automatic pre-processing of massive sample data Cutting, greatly improve work efficiency, lay the foundation for UAV autonomous refueling. ? 2022 IEEE.Accession Number: 20230713591844 -
Record 200 of
Title:Design of MWIR Hadamard coded imaging spectrometer
Author(s):Yang, Ying(1); Hu, Bingliang(1); Li, Libo(1); Wang, Shuang(1); Yan, Qiangqiang(1)Source: Guangxue Jingmi Gongcheng/Optics and Precision Engineering Volume: 30 Issue: 6 DOI: 10.37188/OPE.20223006.0641 Published: March 25, 2022Abstract:In a space Hadamard transform spectral imager (SHTSI) system, encoding the template using digital mirror devices (DMDs) can ensure that the system is miniaturized and lightweight, and has high resolution and high frame rate. However, modulation using DMD causes the focus plane of SHTSI to tilt; consequently, the resultant image obtained from the spectrometer does not match the cooled shield of the detector. This causes image degradation and field of view loss. In this paper, a novel SHTSI system design is proposed to improve the quality of the final image. The design also addresses the issues of cold stop aperture mismatch and field of view accuracy. In this scheme, the design of the front lens contains a tilted and off-center lens, which tilts the image of the object by 24° with respect to the primary focus plane. Based on this method, a SHTSI optical system is designed, and the spot diagram RMS of the full field of the system was calculated to be less than 5 μm. This ensures that the system generates an even image. According to this design scheme, a SHTSI principle model machine is developed. The experiment results show that the evaluation of the restored spectral angular distance of the SHTSI system is better than 0.052. ? 2022, Science Press. All right reserved.Accession Number: 20221411925241 -
Record 201 of
Title:Angiodynamic and optical coupling analysis of skin tissue model under finite pressure
Author(s):Zhao, Hetong(1,2); Zhou, Liang(1); Liu, Zhaohui(1); Qiao, Wenlong(1); Sun, Xiaoxiao(1); Jiang, Le(1); Lyu, Yuanyuan(1)Source: Shengwu Yixue Gongchengxue Zazhi/Journal of Biomedical Engineering Volume: 39 Issue: 3 DOI: 10.7507/1001-5515.202106039 Published: June 25, 2022Abstract:The pulse amplitude of fingertip volume could be improved by selecting the vascular dense area and applying appropriate pressure above it. In view of this phenomenon, this paper used Comsol Multiphysics 5.6 (Comsol, Sweden), the finite element analysis software of multi-physical field coupling simulation, to establish the vascular tissue model of a single small artery in fingertips for simulation. Three dimensional Navier-Stokes equations were solved by finite element method, the velocity field and pressure distribution of blood were calculated, and the deformation of blood vessels and surrounding tissues was analyzed. Based on Lambert Beer's Law, the influence of the longitudinal compression displacement of the lateral light surface region and the tissue model on the light intensity signal is investigated. The results show that the light intensity signal amplitude could be increased and its peak value could be reduced by selecting the area with dense blood vessels. Applying deep pressure to the tissue increased the amplitude and peak of the signal. It is expected that the simulation results combined with the previous experimental experience could provide a feasible scheme for improving the quality of finger volume pulse signal. Copyright ?2022 Journal of Biomedical Engineering. All rights reserved.Accession Number: 20222612298163 -
Record 202 of
Title:Research on Near-infrared Spatial Heterodyne Raman Spectrometer
Author(s):Fan, Bozhao(1,2); Feng, Yutao(1); Wang, Quan(1); Gao, Chi(1,2); Wu, Yang(1,2); Han, Bin(1,2); Chang, Chenguang(1); Li, Juan(1); Li, Yiru(1,2); Zhao, Hengxiang(1); Fu, Di(1)Source: Guangzi Xuebao/Acta Photonica Sinica Volume: 51 Issue: 5 DOI: 10.3788/gzxb20225105.0530001 Published: May 25, 2022Abstract:Spatial Heterodyne Raman Spectroscopy (SHRS) is a new type of Raman spectroscopy detection technology, which has the advantage of high throughput, high spectral resolution, high sensitivity and no moving parts. SHRS can meet the high-sensitivity detection requirements of weak Raman scattered light, and can also obtain clear and sharp Raman spectra. For Raman spectrometers, fluorescence is an inevitable background signal. The fluorescence intensity and the Raman intensity are approximately inversely proportional to the fourth power of the wavelength, so the excitation wavelength of near-infrared light has lower fluorescence than visible light. The excitation wavelengths of near-infrared light are mostly 785 nm, 830 nm and 1 064 nm, of which the shorter 785 nm has larger fluorescence. Although the 1064 nm excitation light has a weaker fluorescence, it requires the near-infrared InGaAs focal plane. Compared with visible detectors, it has higher noise, lower sensitivity and resolution. Therefore, this article chooses the wavelength of 830 nm as the excitation light for Raman spectroscopy detection, and its fluorescence is lower than that of 785 nm. On the other hand, the visible detectors can be used for high-sensitivity detection. For the excitation wavelength of 830 nm, this paper designs, simulates, develops and tests SHRS. The Littrow wavelength of the spectrometer is 842 nm, the theoretical spectral sampling interval is 2.96 cm-1, and the theoretically Raman shift range is 171.71~3 031.04 cm-1. The spatial heterodyne interferometer adopts integrated adhesive technology. To increase the throughput, the field-widened prisms are added to the interferometer. The field angle tolerance of the interferometer is selected to be ±2° to ensure the contrast of the interferogram in actual work, and the corresponding contrast of the ideal interferogram is better than 0.98. The fringe-imaging lens group selects a double telecentric lens group with a magnification of 1. The telecentric configuration guarantees the uniform illumination of the image surface, and the symmetrical structure can effectively balance aberrations and further enhance the stability of the system. A checkerboard target is used to test the processed fringe-imaging lens group. The measured average magnification is 1.001 9 and the relative distortion is 0.19%. The Kr lamp is used as the input light of the system to verify the design parameters of the SHRS prototype. According to the positions of the two spectral lines 877.675 nm and 892.869 nm of the Kr lamp and the corresponding Raman shift, the actual spectral sampling interval is 2.918 2 cm-1. The smaller value compared with the design value is mainly due to the dispersion of the field-widened prism. The actual Littrow wavelength is 841.95 nm, which is close to the theoretical value. The detector selected in this paper does not respond to light with a wavelength greater than 1 000 nm, so the actual Raman shift range is 171.01~2 048.19 cm-1. The design parameter and the simulation of the system are verified. In the Fourier transform of the interferogram to the spectrogram, apodization is needed to suppress the side lobes, and different apodization functions have different degrees of spectral line broadening, resulting in different actual spectral resolution. In rectangular function apodization, the spectral resolution is about 1.207 times the theoretical spectral sampling interval. The effective spectral resolution of the SHRS prototype is 3.35 cm-1. An important parameter to measure the performance of Raman spectrometer is the Signal-to-Noise Ratio (SNR) of the Raman spectrum. We choose the peak intensity of the Raman spectrum after removing the baseline as the signal intensity, and the standard deviation after removing the baseline from the Raman spectrum peak area as the noise, and use the ratio of the two as SNR of the measured Raman spectrum. In the experiment, the excitation light power is 500 mW, and the integration time is 10 s. First, the standard Raman sample cyclohexane is tested. SNR of the main Raman peak at 795.5 cm-1 is 913, and SNR of the weakest Raman peak at 1 341 cm-1 is 15. It can be verified that the SHRS prototype has good Raman spectrum measurement capabilities, as well as high sensitivity and SNR. Secondly, the solid samples calcium carbonate, calcium sulfate and potassium sulfate are tested. These samples are all strong Raman active substances, and the Raman spectrum peaks of various substances can be accurately identified, and SNR of the main Raman spectrum peaks is greater than 300. Finally, experiments are carried out on 75% alcohol solution, glycerin and glucose powder. The Raman activity of these samples is relatively weak, and there are obvious baselines in the measured Raman spectra, indicating that there is a certain fluorescent background in the spectra. However, a clear and accurate Raman spectrum is still obtained, and the main Raman spectrum peaks of various substances can be accurately obtained, and SNR of each spectrum peak is greater than 20. In general, SHRS has higher detection sensitivity and better stability and can meet the analytical requirements of Raman spectroscopy detection. It has certain advantages in the Raman detection of high-fluorescence background substances and has certain development potential in biomedicine, food safety, geological prospecting, planetary exploration, etc. ? 2022, Science Press. All right reserved.Accession Number: 20222412233235 -
Record 203 of
Title:An Optical Path Automatic Alignment Method Based on Dual-target Recognition and Improved Alignment Mathematical Model
Author(s):Guo, Jiafu(1,2); Wang, Zhengzhou(1); Duan, Yaxuan(1); Wang, Li(1); Xie, Zhengmao(1)Source: Guangzi Xuebao/Acta Photonica Sinica Volume: 51 Issue: 11 DOI: 10.3788/gzxb20225111.1114006 Published: November 2022Abstract:The high-power laser device needs to complete optical path self-alignment， analog optical alignment and optical docking alignment before physical experiment starting. With the deepening of physical experiments， the optical docking alignment process of high-power laser device encounters some new problems. First of all， the number of optical targets has changed. In the previous optical docking alignment process， alignment task was performed with the analog laser source turned off. There was only one main laser target in the docking alignment image. Now， in order to reduce the influence of the drift alignment accuracy of the main laser target， the analog laser source is no longer turned off in the alignment process， which means an optical path alignment image contains both an analog laser target and a main laser target. Moreover， optical docking alignment mathematical model has changed， too. In the original high-power laser device， the automatic alignment of 8-path beams adopted the same unit alignment model. The original mathematical model has only one optical target in alignment image instead of multiple optical targets. And the original mathematical model is only for a single-path beam， and the parameter information of multi-path beams is not reflected in the mathematical model. Finally， the docking alignment process of high-power laser was executed in serial in the past， which greatly affected the alignment efficiency. In order to solve the above problems， this paper makes improvements from the following three aspects. For the first problem， according to the characteristics of different optical targets in optical docking alignment images， a dual-optical target recognition algorithm based on circle fitting algorithm is proposed. This algorithm uses the edge pixels of optical objects to perform circle fitting， then calculates their circle fitting ratio. Different optical targets can be recognized by comparing their circle fitting ratio. However， in some special situations， the difference between the circle fitting ratio of the analog laser target and the main laser target is very slight. It is not effective to recognize the dual targets only by the circle fitting ratio. Therefore， a new parameter， based on the circle fitting coefficient， BLOB region number is added as a supplement to the circle fitting coefficient to jointly determine the final target recognition result. For the second problem， this paper build a new automatic alignment mathematical model based on multi-optical path and dual-target. The new mathematical model embodies the characteristics of optical targets well， and improves convergence condition， which could judge whether the distance between the main laser center and target position is less than the given error threshold. For the last problem， this paper improves the efficiency of optical docking alignment by parallel alignment multiple optical paths. The experimental results show that the dual-optical target recognition algorithm proposed in this paper based on circle fitting can recognize analog laser target and main laser target well. Besides， the recognition error accuracy is less than 3 pixels， and the processing time is less than 1 second， which meets the accuracy and efficiency requirements of optical docking alignment of the high-power laser device. Simultaneously， the automatic alignment mathematical model constructed in this paper based on multiple optical paths and dual targets has great significance for the success of optical docking alignment. ? 2022 Chinese Optical Society. All rights reserved.Accession Number: 20224513074585 -
Record 204 of
Title:Holographic Imaging through Scattering Medium Based on Statistical Average Method
Author(s):Zhang, Hui(1,2); Zhang, Zaikun(1,2); Kong, Depeng(1); He, Zhengquan(1)Source: Guangzi Xuebao/Acta Photonica Sinica Volume: 51 Issue: 6 DOI: 10.3788/gzxb20225106.0609001 Published: June 1, 2022Abstract:Light is an important vehicle for observing and obtaining image information about objects and is an important way of perceiving the environment. However， in the natural environment， there are often small particles or obstacles between the observer and the observed object that prevent direct imaging of the observed object. When there is a scattering medium in the imaging optical path， photons are scattered with the scattering medium and the incident wavefront of the light is destroyed， resulting in a change in the direction of light propagation， and the photoelectric imaging system does not work properly under these conditions. To solve the problem of not being able to image the observed object clearly in the presence of the scattering medium， in this paper， statistical averaging and lensless Fourier transform digital holography are used to achieve imaging through the scattering medium. The speckle is averaged through the rotating scattering medium， and the exposure time of the camera is increased so that the time average of the scattering field replaces the collective average， thus eliminating the effect of the random phase introduced by the scattering medium on the imaging process. This method of digital holography using statistical averaging and lensless Fourier transform has the advantages of simple and compact optical path structure， fast reconstruction speed， and low cost. Compared to wavefront shaping technology， transmission matrix technology， adaptive optics technology， and other methods of imaging through scattering media， this method does not require phase correction and complex image processing， target scanning， wavefront shaping， and other complicated operations.The experiments firstly investigate the effects of ground glass rotation speed and CCD exposure time on the peak signal-to-noise ratio of reconstructed images. The experiments show that different rotation speeds require different exposure times to achieve the highest peak signal-to-noise ratio， and the faster the rotation speed， the shorter the time required to reach the highest peak signal-to-noise ratio. The highest peak signal-to-noise ratio of 21.44 dB was obtained for the four sets of data at a rotation speed of 1.5 r/min and an exposure time of 800 ms. After obtaining the optimal experimental conditions， the imaging experiment through a single scattering medium was carried out. The laser light is divided into two beams by the beam splitter， one beam of light irradiates the object for transmission or reflection and then passes through the rotating ground glass as the object light， and the other beam is reflected by the mirror. After the incident on the convex lens， the convex lens converts the light beam from a plane wave to a spherical wave emitted by a point light source， to meet the conditions of lensless Fourier transform digital holographic recording. Then the reference light and the object light interfere after being combined by the beam combiner， and finally， the interference speckle image is recorded by the CCD. The experiments show that the method can reconstruct the object information for both transmissive resolution plates and reflective dolls and coins. On this basis， to solve the problem that actual imaging scenes rarely have a scattering medium with rotation or small displacement， we extend the application scenario of the method by introducing a stationary scattering medium. Experiments are carried out by loading a random speckle image on a spatial light modulator to simulate a stationary scattering medium. The experiments show that although the imaging quality is reduced compared to that through a single rotating scattering medium， the method is still able to image the target object clearly and achieve imaging through a double scattering medium. Finally， the reconstructed image is subjected to Butterworth high-pass filtering， and the contrast of the reconstructed image is effectively improved after the filtering. ? 2022 Chinese Optical Society. All rights reserved.Accession Number: 20224413027433