2024

• Record 145 of
  
  Title:Single-photon ranging lidar based on multi-repetition-rate pulse train correlation and accumulation
  
  Author(s):Kang, Yan(1); Wang, Xiaofang(1,2); Zhang, Tongyi(1,2); Zhao, Wei(1,2)
  Source:Optics Letters
  Volume: 49  Issue: 6  DOI: 10.1364/OL.511411  Published: March 15, 2024  
  Abstract:A single-photon lidar based on multi-repetition-rate pulse train correlation and accumulation is proposed, and a ranging experiment is conducted on a 32 m target. By accumulating the correlation ranging results of pulse trains with internal spacings of 80, 100, and 125 ns, the signal-to-noise ratio of the cross correlation function is improved by about three-fold, which enables our method to improve the ranging precisions by more than 20% compared with the single repetition-rate method, and the shorter the acquisition time, the more obvious the advantage will be. Experimental results show that at an acquisition time of 0.01 s, our method can still achieve a ranging precision of 2.59 cm, while the single repetition-rate method can no longer obtain effective ranging results at this time. This method will be of great significance for realizing high-speed, large-scale unambiguous single-photon lidar ranging. © 2024 Optica Publishing Group.
  Accession Number: 20241215777230
• Record 146 of
  
  Title:Random laser emission at 1064 and 1550 nm in a Er/Yb co-doped fiber-based dual-wavelength random fiber laser
  
  Author(s):Li, Zhe(1,2); She, Shengfei(1,2); Li, Gang(1,2); Gao, Qi(1,2); Ju, Pei(1,2); Gao, Wei(1,2); Sun, Chuandong(1); Wang, Yishan(1)
  Source:Optics Express
  Volume: 32  Issue: 4  DOI: 10.1364/OE.508025  Published: February 12, 2024  
  Abstract:Dual-wavelength fiber lasers operating with a wide spectral separation are of considerable importance for many applications. In this study, we propose and experimentally explore an all-fiberized dual-wavelength random fiber laser with bi-directional laser output operating at 1064 and 1550 nm, respectively. A specially designed Er/Yb co-doped fiber, by optimizing the concentrations of the co-doped Er, Yb, Al and P, was developed for simultaneously providing Er ions gain and Yb ions gain for RFL. Two spans of single mode passive fibers are employed to providing random feedback for 1064 and 1550 nm random lasing, respectively. The RFL generates 5.35 W at 1064 nm and 6.61 W at 1550 nm random lasers. Two power amplifiers (PA) enhance the seed laser to 50 W at 1064 nm with a 3 dB bandwidth of 0.31 nm and 20 W at 1550 nm with a 3 dB bandwidth of 1.18 nm. Both the short- and long-term time domain stabilities are crucial for practical applications. The output lasers of 1064 and 1550 nm PAs are in the single transverse mode operating with a nearly Gaussian profile. To the best of our knowledge, this is the first demonstration of a dual-wavelength RFL, with a spectral separation as far as about 500 nm in an all-fiber configuration. © 2024 Optica Publishing Group.
  Accession Number: 20240815569595
• Record 147 of
  
  Title:Slicing of large-size single crystals by ultrafast laser with external stress assistance
  
  Author(s):Wang, Lifeng(1); Liu, Lili(1,2); Wang, Yinan(1); Li, Xun(1); Li, Chenchen(1); Li, Ming(1)
  Source:Chinese Optics Letters
  Volume: 22  Issue: 8  DOI: 10.3788/COL202422.081601  Published: August 1, 2024  
  Abstract:The existing single-crystal slicing techniques result in significant material wastage and elevate the production cost of premium-quality thin slices of crystals. Here we report (for the first time, to our knowledge) an approach for vertical slicing of large-size single-crystal gain materials by ultrafast laser. By employing aberration correction techniques, the optimization of the optical field distribution within the high-refractive-index crystal enables the achievement of a continuous laser-modified layer with a thickness of less than 10 μm, oriented perpendicular to the direction of the laser direction. The compressed focal spot facilitates crack initiation, enabling propagation under external forces, ultimately achieving the successful slicing of a Φ12 mm crystal. The surface roughness of the sliced Yb:YAG is less than 2.5 μm. The results illustrate the potential of low-loss slicing strategy for single-crystal fabrication and pave the way for the future development of thin disk lasers. © 2024 Chinese Optics Letters.
  Accession Number: 20243516933944
• Record 148 of
  
  Title:Detecting the Background-Similar Objects in Complex Transportation Scenes
  
  Author(s):Sun, Bangyong(1); Ma, Ming(1); Yuan, Nianzeng(2); Li, Junhuai(2); Yu, Tao(3)
  Source:IEEE Transactions on Intelligent Transportation Systems
  Volume: 25  Issue: 3  DOI: 10.1109/TITS.2023.3268378  Published: March 1, 2024  
  Abstract:With the development of intelligent transportation systems, most human objects can be accurately detected in normal road scenes. However, the detection accuracy usually decreases sharply when the pedestrians are merged into the background with very similar colors or textures. In this paper, a camouflaged object detection method is proposed to detect the pedestrians or vehicles from the highly similar background. Specifically, we design a guide-learning-based multi-scale detection network (GLNet) to distinguish the weak semantic distinction between the pedestrian and its similar background, and output an accurate segmentation map to the autonomous driving system. The proposed GLNet mainly consists of a backbone network for basic feature extraction, a guide-learning module (GLM) to generate the principal prediction map, and a multi-scale feature enhancement module (MFEM) for prediction map refinement. Based on the guide learning and coarse-to-fine strategy, the final prediction map can be obtained with the proposed GLNet which precisely describes the position and contour information of the pedestrians or vehicles. Extensive experiments on four benchmark datasets, e.g., CHAMELEON, CAMO, COD10K, and NC4K, demonstrate the superiority of the proposed GLNet compared with several existing state-of-the-art methods. © 2000-2011 IEEE.
  Accession Number: 20232114129082
• Record 149 of
  
  Title:Dual-complexities based on straightforward neighborhood pixel prediction in pixel-value-ordering framework for reversible data hiding
  
  Author(s):Li, Zijing(1); Liao, Xuewen(1); Fan, Guojun(1); Zhang, Xiaoran(1); Pan, Zhibin(1,2,3)
  Source:Displays
  Volume: 84  Issue:   DOI: 10.1016/j.displa.2024.102749  Published: September 2024  
  Abstract:PVO-based schemes are the widely-used reversible data hiding (RDH) techniques. Benefiting from the good prediction performance, the stego-image can have a high quality. However, the complexity metric of PVO is still not good enough. The two main limitations are: the block-based context pixels are not highly correlated with the predicted pixel, and the fluctuation-based complexity calculation methods cannot comprehensively represent the real prediction result. Unlike the existing complexity metrics, we consider this problem from a novel viewpoint of neighborhood pixel prediction (NPP), i.e., using the prediction pixel to predict the unmodified neighborhood pixels of a predicted pixel. The neighborhood pixels are more reliable than the context pixels and the generated neighborhood prediction-errors (NPEs) are utilized to represent the real prediction-error (RPE). Two new features are extracted from NPEs as Dual-complexities to determine the embedding order. Experimental results indicate the quality of the stego-image can be improved significantly by using our proposed Dual-complexities in the related PVO-based schemes, and it can be directly extended to other schemes in PVO framework as well. © 2024 Elsevier B.V.
  Accession Number: 20242316214170
• Record 150 of
  
  Title:Compensation control strategy for photoelectric stabilized platform based on disturbance observation
  
  Author(s):Chang, Sansan(1,2,5); Cao, Jianzhong(1,5); Pang, Ji(3); Zhou, Feihang(3); Chen, Weining(1,4,5)
  Source:Aerospace Science and Technology
  Volume: 145  Issue:   DOI: 10.1016/j.ast.2024.108909  Published: February 2024  
  Abstract:The accuracy and stability of the photoelectric stabilized platform will be inevitably affected by the friction disturbance and the base platform disturbance in the actual operation. To improve the disturbance rejection performance, two kinds of the disturbance observers are employed and compared in this paper, including the adaptive proportion-integrator observer and the robust sliding mode observer. The disturbances of the friction torque and the moving base are observed, then these observed values are compensated to the voltage loop by the feedback and feedforward, respectively. While the disturbances of the friction torque and the shaking base are compensated, the parameters of the speed stability loop are also tuned to improve the performance of this photoelectric stabilized platform. Finally, the effectiveness of the proposed method is verified by both simulations and experiments. The results show that the proposed disturbance compensation control method based on the sliding mode observer has strong robustness and can effectively reduce the impact of system disturbances. © 2024
  Accession Number: 20240615508203
• Record 151 of
  
  Title:Multiple marine algae identification based on three-dimensional fluorescence spectroscopy and multi-label convolutional neural network
  
  Author(s):Li, Ruizhuo(1,2); Gao, Limin(1); Wu, Guojun(1,3); Dong, Jing(1,2)
  Source:Spectrochimica Acta - Part A: Molecular and Biomolecular Spectroscopy
  Volume: 311  Issue:   DOI: 10.1016/j.saa.2024.123938  Published: April 15, 2024  
  Abstract:Accurate identification of algal populations plays a pivotal role in monitoring seawater quality. Fluorescence-based techniques are effective tools for quickly identifying different algae. However, multiple coexisting algae and their similar photosynthetic pigments can constrain the efficacy of fluorescence methods. This study introduces a multi-label classification model that combines a specific Excitation-Emission matric convolutional neural network (EEM-CNN) with three-dimensional (3D) fluorescence spectroscopy to detect single and mixed algal samples. Spectral data can be input directly into the model without transforming into images. Rectangular convolutional kernels and double convolutional layers are applied to enhance the extraction of balanced and comprehensive spectral features for accurate classification. A dataset comprising 3D fluorescence spectra from eight distinct algae species representing six different algal classes was obtained, preprocessed, and augmented to create input data for the classification model. The classification model was trained and validated using 4448 sets of test samples and 60 sets of test samples, resulting in an accuracy of 0.883 and an F1 score of 0.925. This model exhibited the highest recognition accuracy in both single and mixed algae samples, outperforming comparative methods such as ML-kNN and N-PLS-DA. Furthermore, the classification results were extended to three different algae species and mixed samples of skeletonema costatum to assess the impact of spectral similarity on multi-label classification performance. The developed classification models demonstrated robust performance across samples with varying concentrations and growth stages, highlighting CNN's potential as a promising tool for the precise identification of marine algae. © 2024 Elsevier B.V.
  Accession Number: 20240815614850
• Record 152 of
  
  Title:Design of electronic readout system for resistive anode based on FPGA
  
  Author(s):Song, Yuchao(1); Zhang, Wenwen(1); Zheng, Jinkun(2,3); Yang, Yang(2); Bai, Yonglin(2,3); La, Anpeng(1); Duan, Jinyao(2,3)
  Source:IEICE Electronics Express
  Volume: 21  Issue: 10  DOI: 10.1587/elex.21.20240117  Published: 2024  
  Abstract:This paper presents an electronic readout system based on the resistance anode, which is capable of processing the output signal from the resistance anode. This design divides the electronic readout circuit into two parts: analog circuit design and digital circuit design. The analog pre-processing circuit the electric charge signal from the resistive anode detector into a voltage signal and amplifies it and the digital part consists of a trapezoidal double-channel shaping algorithm implemented in FPGA. This design overcomes pulse pile-up at high count rates. © 2024 Institute of Electronics Information Communication Engineers. All rights reserved.
  Accession Number: 20242416256529
• Record 153 of
  
  Title:Design and Control Strategy of Wedge-type Automatic Leveling Mechanism
  
  Author(s):Li, Xiangyu(1); Han, Jingyu(1,2); Hao, Wei(1); Xie, Meilin(1); Lian, Xuezheng(1); Ruan, Ping(1); Tian, Guangyuan(1)
  Source:Guangzi Xuebao/Acta Photonica Sinica
  Volume: 53  Issue: 9  DOI: 10.3788/gzxb20245309.0922004  Published: September 2024  
  Abstract:The theodolite，an optical instrument utilized for measuring the azimuth and pitch angle of spatial targets， operates on the principle of angle measurement， finding extensive application in aviation，construction， and various other industries. Functioning as a precision optical measuring device， the theodolite necessitates meticulous high-precision leveling through a leveling mechanism prior to operation. This ensures alignment of the vertical axis with the earth's plumb line，thereby guaranteeing the accuracy of azimuth and pitch angle measurements within the geodetic coordinate system. The leveling mechanism within the theodolite predominantly consists of screw jack and wedge types，both manually operated. Employing a cyclic approximation leveling mode， the theodolite achieves semi-locking post-coarse leveling at wide angles，followed by re-locking after fine leveling at narrow angles，thereby completing the leveling process while maintaining adequate stable support. However， in practical engineering applications， the proficiency and experience of the operator significantly impact the time required to adjust the theodolite's vertical axis to an error of ≤5 ″，a process that typically takes around 30 minutes. This duration constitutes 50% of the total deployment time of the theodolite. Attaining a tilt error of ≤2 ″necessitates additional leveling cycles and prolonged operation time. Consequently，the time-consuming nature of high-precision manual leveling severely impedes the deployment speed of the theodolite. Moreover，the cyclic approximation leveling mode's influence on fine leveling of the locking mechanism，particularly at small angles，relies on the elastic or plastic deformation of transmission components within the leveling mechanism. Repeated leveling cycles hasten the deterioration of the leveling mechanism，significantly undermining the theodolite's reliability. Addressing the challenges associated with high-precision manual leveling，this paper introduces the design of an automatic leveling mechanism of the wedge type， characterized by stable self-locking properties，extensive stroke，and high resolution. Through physical modeling，calculation models for anti-torsion friction force， motor torque transmission， leveling angle resolution， and stroke are established，facilitating the determination of core design parameters. Furthermore，an analysis of the leveling strategy for the wedge-type automatic leveling mechanism is conducted，proposing a parallel leveling control strategy as an alternative to the commonly used serial approach in manual operation. This parallel strategy enhances leveling efficiency by enabling electro-mechanical leveling components to achieve synchronized motion. Experimental validation confirms that the designed wedge-type automatic leveling mechanism achieves leveling within a range of ±0.25° ，with a resolution of © 2024 Chinese Optical Society. All rights reserved.
  Accession Number: 20244117178917
• Record 154 of
  
  Title:Effects and optimizations of image charge technology on the imaging performance of capacitive division image readout MCP detectors
  
  Author(s):Wang, Bo(1); Yang, Kai(1,2); Bai, Yonglin(1); Cao, Weiwei(1); Bai, Xiaohong(1); Zheng, Jinkun(1)
  Source:Nuclear Instruments and Methods in Physics Research, Section A: Accelerators, Spectrometers, Detectors and Associated Equipment
  Volume: 1069  Issue:   DOI: 10.1016/j.nima.2024.169879  Published: December 2024  
  Abstract:A finite element model is proposed to investigate the impact of image charge technology on the imaging performance of capacitive division image readout (C-DIR) devices. Through detailed simulation analysis, we explore the charge density of the induction layer and each electrode layer in the multilayer capacitive anode. The position nonlinearity is calculated for various resistances per square of the induction layer and substrate thicknesses. The simulation results indicate a strong linear correlation between the position nonlinearity and substrate thickness, and an exponential decay relationship with the logarithmic resistance per square of the induction layer. The C-DIR detector is experimentally tested for imaging nonlinearity and counting rate, with the resistance per square of the induction layer ranging from 0.005 to 1000 MΩ, and the substrate thickness ranging from 1 to 5 mm. The experimental results validate the simulation conclusions and reveal the impact of the "charge accumulation effect" and "shielding effect" on the imaging performance of the detector, as well as the "imaging compression" phenomenon. Optimized image charge readout technology enables the C-DIR detector to achieve an imaging nonlinearity of 1.53% in the experiment. © 2024
  Accession Number: 20243817070436
• Record 155 of
  
  Title:A novel demodulation method of the channeled modulated polarization imaging pictures by hybrid feature modulated autoencoders
  
  Author(s):Zhang, Ning(1); Zhao, Mingfan(1,2); Zhang, Zhinan(1); Liu, Jie(1); Zhang, Yunyao(3); Li, Siyuan(1)
  Source:Optics Express
  Volume: 32  Issue: 18  DOI: 10.1364/OE.530310  Published: August 26, 2024  
  Abstract:Channeled modulated polarization imaging technology offers advantages owing to its simple structure and low cost. However, the loss of high-frequency information due to channel crosstalk and the filter demodulation method has consistently hindered the mature application of this technology. We analyzed the data structure of pictures detected using this technology and proposed a demodulation method using hybrid feature modulated autoencoders. Training the network with a substantial number of images, it effectively addresses the issue of high-frequency information loss and demonstrates proficient demodulation capabilities for both simulated and real detected pictures. © 2024 Optica Publishing Group under the terms of the Optica Open Access Publishing Agreement.
  Accession Number: 20243516970851
• Record 156 of
  
  Title:Blue-green emitting ZnS0.75O0.25:Ce3+,x%Tb3+ phosphor with tunable fluorescence lifetime
  
  Author(s):Xing, Xue(1,2,3); Cao, Weiwei(1); Wu, Zhaoxin(2); Bai, Xiaohong(1); Gao, Jiarui(1); Liang, Xiaozhen(1); Wang, Bo(1); Wang, Chao(1); Shi, Dalian(1); Lv, Linwei(1); Bai, Yonglin(1)
  Source:Materials Letters
  Volume: 372  Issue:   DOI: 10.1016/j.matlet.2024.137028  Published: October 1, 2024  
  Abstract:A series of ZnS0.75O0.25:0.1%Ce3+,x%Tb3+ phosphors were prepared by high temperature solid state reaction method. These phosphors exhibited two mixed phases consisting of hexagonal phase ZnS and hexagonal phase ZnO with the average particle size of 13.83 μm and emitted blue-green light. The luminescence mechanism consisted of Zn vacancy defects, the 5d1 → 2F5/2 radiative transitions of Ce3+, the 5D4 → 7F5 and 5D4 → 7F6 radiative transition of Tb3+ induced by the energy transfer of Ce3+ → Tb3+. An equation for the variation of the fluorescence lifetime of ZnS0.75O0.25:0.1%Ce3+,x%Tb3+ phosphors with concentration of Tb3+ fraction was obtained by exponential fitting. The short fluorescence lifetime could be tuned within the range of 113 μs to 550 μs with the increase of Tb3+ concentration, and the color was tunable from blue to blue-green, which is of important application in the field of high-energy particle detection. © 2024 Elsevier B.V.
  Accession Number: 20243116772657