2024

• Record 49 of
  
  Title:Optimization design of cooling system stability of double crystal monochromator
  
  Author(s):Jiang, Bo(1); Chu, Yuanbo(2); Guo, Yifan(2); Dong, Yiming(1)
  Source: Proceedings of SPIE - The International Society for Optical Engineering  Volume: 13080  Issue:   DOI: 10.1117/12.3025729  Published: 2024  
  Abstract:With the development of scientific research, the stability of synchrotron radiation has been paid more attention. The liquid vibration will change the liquid flow state, cause the vibration of the pipe surface, and lead to the crystal jitter. Aiming at the stability requirements of the high-stability monochromator of the partial beam line of SSRF, ANSYS workbench software was used to analyze and optimize the structure, and a cooling pipe system with more stable structure was designed. This paper also analyzes the effect of cooling system vibration on crystal. The test results of the prototype show that the resolution of the device can reach 1 urad and the repetition accuracy is less than 1.071 urad. All the indexes meet the needs of the monochromator. © 2024 SPIE.
  Accession Number: 20241115749947
• Record 50 of
  
  Title:Key assembling and alignment technology of laser communication opto-mechanical system
  
  Author(s):Cao, Mingqiang(1); Lei, Yu(1); Shi, Yuanyuan(1); Ren, Wangtao(1); Liu, Yong(1); Li, Xiaoyan(1); Hou, Xiaohua(1)
  Source: Proceedings of SPIE - The International Society for Optical Engineering  Volume: 13104  Issue:   DOI: 10.1117/12.3024118  Published: 2024  
  Abstract:The optical mechanical system of laser communication has the characteristics of compact structure, highly integration, and multi optical axes integration. The consistency between transmission and reception, divergence angle, and wavefront of the optical telescope of the system are very important indicators. In response to the above difficulties and characteristics, this article conducts research on computer-Aided adjustment, fiber optic coupling, and transceiver consistency testing. Currently, coaxial and off-Axis optical telescope aligning technologies, high-precision fiber optic coupling debugging technology, and turntable linked space optical path transceiver consistency assembling technology have been formed, which can achieve the target requirements of transceiver consistency of 3μrad and system divergence angle of 30μrad. © COPYRIGHT SPIE. Downloading of the abstract is permitted for personal use only.
  Accession Number: 20241816027441
• Record 51 of
  
  Title:Simulation of evaporation ablation dynamics of materials by nanosecond pulse laser of Gaussian beam and flat-top beam
  
  Author(s):Yin, Pei-Qi(1,2); Xu, Bo-Ping(1,2); Liu, Ying-Hua(1,2); Wang, Yi-Shan(1,2); Zhao, Wei(1,2); Tang, Jie(1,2)
  Source: Wuli Xuebao/Acta Physica Sinica  Volume: 73  Issue: 9  DOI: 10.7498/aps.73.20231625  Published: May 5, 2024  
  Abstract:Based on the established two-dimensional asymmetric model of the interaction between a nanosecond pulse laser and metallic aluminum, the effect of beam shaping on the evaporation ablation dynamics during the ablation of metallic aluminum by a nanosecond pulse laser is simulated. The results show that plasma shielding, which has a significant influence on the ablation properties of the target, occurs mainly in the middle phase and late phase of the pulse. Among the three laser profiles, the Gaussian beam has the strongest shielding effect. As the diameter of the reshaped flat-top beam increases, the shielding effect gradually weakens. The two-dimensional spatial distribution of target temperature is relatively different between ablation by a Gaussian beam and that by a flat-top beam. For the Gaussian beam, the center of the target is first heated, and then the temperature spreads in radial direction and axial direction. For the flat-top beam, due to the uniform energy distribution, the target is heated within a certain radial range simultaneously. Beam shaping has a great influence on the evaporation ablation dynamics of the target. For the Gaussian beam, the center of the target is first ablated, followed by the radial ablation. For the flat-top beam, the evaporation time of the target surface is delayed due to the lower energy density after the beam has been shaped. In addition, the target evaporates simultaneously in a certain radial range due to the more uniform distribution of laser energy. For each of the three laser profiles, the evaporation morphology of the target resembles the intensity distribution of the laser beam. The crater produced by the Gaussian beam is deep in the center and shallow on both sides, while it becomes relatively flat by the flat-top beam. © 2024 Institute of Physics, Chinese Academy of Sciences. All rights reserved.
  Accession Number: 20241916068119
• Record 52 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 53 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 54 of
  
  Title:Inverse design of high efficiency and large bandwidth power splitter for arbitrary power ratio based on deep residual network
  
  Author(s):Wen, Jin(1,2); Wu, Zhengwei(1); Zhang, Hui(1); Wang, Qian(1); Yu, Huimin(1); Zhang, Ying(1); Pan, Yu(1); Liu, Zhanzhi(1)
  Source: Optical and Quantum Electronics  Volume: 56  Issue: 4  DOI: 10.1007/s11082-023-06165-x  Published: April 2024  
  Abstract:In this research, we propose the deep Residual Network to realize the inverse design of a low loss 1 × 3 port power splitter with an area of 2.6 × 2.6 μm2 on a standard silicon-on-insulator platform. Then the area is used as the inverse design region and discretized into 20 × 20 square pixels, where each pixel can be switched between the two random initial states of silicon square with and without holes. Besides, we use the direct binary search algorithm to change the state of the pixels so that the distribution of all pixels in the inverse design region reaches the optimal value of the algorithm. While training the network, inputting spectral transmission response, and using the etched hole vector positions as a label for the inverse design, it achieved an accuracy of 0.9111 and a correlation coefficient greater than 0.88 for all three ports. Finally, we demonstrated 1 × 3 power splitters with 1:2:1, 1:2:1.5, 1:3:1, and 1:3:2 distribution ratios and a more than 90% maximum transmission efficiency with bandwidth from 1450 to 1650 nm while having a low insertion loss of less than 0.45 dB. This research can be found potential applications in the design of photonic devices with high performance and small size. © 2024, The Author(s), under exclusive licence to Springer Science+Business Media, LLC, part of Springer Nature.
  Accession Number: 20240515480379
• Record 55 of
  
  Title:A reversible data hiding method based on bitmap prediction for AMBTC compressed hyperspectral images
  
  Author(s):Zhang, Xiaoran(1,2); Pan, Zhibin(2,5); Zhou, Quan(3); Fan, Guojun(2); Dong, Jing(4)
  Source: Journal of Information Security and Applications  Volume: 81  Issue:   DOI: 10.1016/j.jisa.2023.103697  Published: March 2024  
  Abstract:In the transmission of hyperspectral images that have been compressed using absolute moment block truncation coding (AMBTC), confidentiality and security of crucial information is often a concern. Although many data hiding (DH) methods based on AMBTC work well in guaranteeing a large amount of secret information can be embedded, the requirements of actual user scenarios, such as reversibility and imperceptibility, are degraded sometimes. To address these challenges, we propose an embedding pattern that utilizes bitmap prediction to embed secret information within the bitmaps while preserving the standard format of AMBTC codes and enabling recovery of the cover image without loss. Our proposed method, therefore, belongs to the category of reversible data hiding (RDH) techniques. Since the embedding distortion (ED) reduction is an essential object, an adaptive embedding order based on the features of AMBTC codes is conducted. Furthermore, we propose a dynamical embedding scheme to reduce ED when we are striving to achieve a larger embedding capacity (EC). © 2024 Elsevier Ltd
  Accession Number: 20240315396843
• Record 56 of
  
  Title:Bit Error Rate Performance Study of UWOC System Based on Multiple Degenerate Composite Channels
  
  Author(s):Zhang, Jianlei(1); Zhang, Pengwei(1); Zhu, Yunzhou(2); Tian, Yuxin(1); Li, Jieyu(1); Yang, Yi(1); He, Fengtao(1)
  Source: Guangzi Xuebao/Acta Photonica Sinica  Volume: 53  Issue: 3  DOI: 10.3788/gzxb20245303.0301002  Published: March 2024  
  Abstract:Underwater Wireless Optical Communication (UWOC) capitalizes on the blue-green segment of the light spectrum which is subject to minimal attenuation in marine environments, thereby rendering it optimal for the conveyance of information. The advantages of UWOC are manifold, it boasts of swift data transmission, negligible latency, and fortified confidentiality. However, UWOC grapples with significant barriers which encompass the limitation of transmission range and the deleterious effects attributable to the intrinsic properties of seawater, as well as marine turbulence-factors like absorption, scattering, bubbles and turbulence that collectively compromise communicative efficiency. To systematically confront these impediments and to gauge the comprehensive influence of the aforementioned factors on UWOC system efficacy, this inquiry has formulated an integrative underwater wireless optical channel model. This archetype not only encapsulates solitary influences but also their concomitant interactions and aggregate impact on signal transmission. By harnessing the Mie scattering theorem, the research meticulously delineates the volume scattering function, the scattering coefficient, and the phase function of microbubble assemblages in seawater—pivotal determinants essential for the assessment of scattering phenomena on the propagation of optical signals. Addressing turbulence, an elaborate channel model featuring a mixed exponential generalized Gamma distribution is employed, defining the statistical behavior of turbulence to faithfully represent the stochastic and unpredictable nature of the channel. This study extends its analysis to include the repercussion of signal attenuation and acoustic noise as a consequence of turbulence, effectively projecting these perturbations onto the optical signals disseminated through the composite channel. Importantly, it elucidates a closed-form expression for the Bit Error Ratio (BER) within the composite channel, employing On-Off Keying (OOK) modulation, thus establishing a theoretical groundwork for the analysis of UWOC system performance. The research delves into the impact of critical determinants such as turbulence strength, bubble density, transmission range, and marine water quality on the BER metrics of UWOC systems. It is discerned that heightened turbulence intensity incrementally necessitates a greater minimum Signal to Noise Ratio (SNR) at the receiver end to maintain a predetermined average BER. Consistent with this SNR, an augmentation in turbulence intensity conspicuously degrades system throughput, inducing a systematic deterioration in BER performance. Within a transparent seawater milieu at a transmission span of 20 m, with a bubble concentration of 3 × 106 per cubic volume, the system′s mean BER is recorded at 4.57 × 10-4. As the bubble density escalates to 9 × 106 and subsequently to 9 × 107 per cubic volume, the average BER correspondingly declines to 5.76 × 10-4 and 1.19 × 10-2. In scenarios of turbulence characterized by a scintillation index of 1.932 8, the system is adept at sustaining low BER transmissions. Ensuring dependable communication quality with an average BER falling below 10-3 across an array of aquatic environments—be it crystalline seawater, littoral waters, or murky harbor waters—the utmost permissible transmission distances with bubble presence(at a density of 1 × 107 per cubic volume)are confined to 22.5 m, 10.4 m, and 2.3 m respectively. Absent bubble interference, these distances are extendable to 28.0 m, 13.5 m, and 2.7 m. Given the pronounced absorption and scattering induced by elevated turbidity and suspended particulates, securing long-range communication in silt-laden harbor waters presents a significant hurdle. Additionally, the study substantiates that elevating the link distance precipitates an almost linear augmentation in BER, indicative of a noteworthy degeneration in signal integrity. The outcomes not only underscore the exigency of crafting and fine-tuning UWOC systems attuned to the vicissitudes of the oceanic realm but also accentuate the latent efficacy of modulation methodologies and channel coding strategies as instrumental in amplifying system competence. © 2024 Chinese Optical Society. All rights reserved.
  Accession Number: 20241215775065
• Record 57 of
  
  Title:Optical design of a visible/short-wave infrared common-aperture optical system with a long focal length and a wide field-of-view
  
  Author(s):Yan, Aqi(1,2); Chen, Weining(1,2); Li, Qianxi(1,3); Guo, Min(1); Wang, Hao(1,2)
  Source: Applied Optics  Volume: 63  Issue: 9  DOI: 10.1364/AO.517643  Published: February 20, 2024  
  Abstract:Addressing the urgent need for long-distance dim target detection with a wide field-of-view and high sensitivity, this paper proposes a visible and short-infrared dual-band common-aperture optical system characterized by a broad field and extended focal length. To achieve system miniaturization and high-sensitivity target detection, the visible and infrared optical systems share a Ritchey-Chretien primary and secondary mirror. The primary optical path is segmented into visible light (0.45–0.75 µm) and short-wave infrared (SWIR) (2–3 µm) bands by a dichroic spectral splitter prism. The SWIR optical system utilizes four short-wave cooled infrared detectors, and wide-field stitching is achieved using a field-of-view divider. While ensuring the high cold-shield efficiency of cooled infrared detectors, this common-aperture optical system delivers visible and SWIR dual-band images with expansive fields, elongated focal lengths, and sizable apertures. The visible-light optical system has a focal length of 277 mm, a field-of-view of 2.3◦ × 2.3◦, and an entrance pupil diameter of 130 mm. Meanwhile, the SWIR optical system features a focal length of 480 mm, a field-of-view of 2.26◦ × 1.8◦ and an entrance pupil diameter of 160 mm. The design outcomes suggest that the imaging quality of the optical system approaches the diffraction limit. This visible/SWIR common-aperture optical system exhibits high sensitivity, a large field-of-view, compact structure, and excellent imaging quality, thereby meeting the requirements for long-distance dim target detection and imaging. © 2024 Optica Publishing Group.
  Accession Number: 20241315795896
• Record 58 of
  
  Title:Fast sampling based image reconstruction algorithm for sheared-beam imaging
  
  Author(s):Chen, Ming-Lai(1,2,3); Ma, Cai-Wen(1,2,3); Liu, Hui(1,2,3); Luo, Xiu-Juan(1,2,3); Feng, Xu-Bin(1,2); Yue, Ze-Lin(1,3); Zhao, Jing(1,3)
  Source: Wuli Xuebao/Acta Physica Sinica  Volume: 73  Issue: 2  DOI: 10.7498/aps.73.20231254  Published: January 20, 2024  
  Abstract:Sheared-beam imaging (SBI) is an unconventional ground-based optical imaging technique. It breaks through the traditional optical imaging concept by using three coherent laser beams, which are laterally displaced at the transmit plane, to illuminate the target, reconstructing the target image from echo signals. However, the echo data sampling of the imaging system is still not fast enough to reconstruct the high resolution and clear image of the target when imaging the target that is at rapidly changing position and attitude. In order to solve this problem, in this work an image reconstruction method is proposed based on five-beam fast sampling. An emitted beam array arranged in the cross shape with a central symmetrical structure is proposed, and the encoding and decoding method of the imaging system are changed. With a single exposure, the echo signals carry more spectrum information of the target, and the number of reconstructed images can be increased from 1 to 8, which quickly suppresses the speckle effect of the reconstructed image. Firstly, the principle of the imaging technique based on fast sampling is presented. Then, an image reconstruction algorithm based on fast sampling is studied. Eight groups of phase differences and amplitude information of the target can be extracted from echo signals. The wavefront phases are solved by the least-squares method, and wavefront amplitude can be obtained by the algebraic operation of speckle amplitude. The target image is reconstructed by the inverse Fourier transform. The simulation results show that comparing with the traditional three-beam image reconstruction method, the sampling times of echo data needed to obtain the same quality image are reduced from 20 to 5, which greatly reduces the sampling times of echo data and improves the sampling rate of echo data. © 2024 Chinese Physical Society.
  Accession Number: 20240815605338
• Record 59 of
  
  Title:Fabrication of large aspect ratio single crystal diamond microchannel by femtosecond laser
  
  Author(s):Wang, Ning(1,2); Zhang, Jingzhou(1,2); Zhao, Hualong(1,2); Zhao, Wei(1)
  Source: Proceedings of SPIE - The International Society for Optical Engineering  Volume: 13104  Issue:   DOI: 10.1117/12.3016198  Published: 2024  
  Abstract:As heat dispersing materials, Diamond has high thermal conductivity, extremely low coefficient of thermal expansion, low coefficient of friction, and good chemical stability, which have broad application prospects in the field of high-power device heat dissipation. This study aims to address the inability of traditional laser processing methods to meet the processing requirements of high aspect ratio diamond heat dissipation microchannels. Based on a femtosecond laser fiveaxis machining system, a five-axis attitude alternating machining method is used to study the forming size, surface roughness, and aspect ratio of femtosecond laser surface microchannels, and to compare it with the direct machining method using a galvanometer. The experimental results show that using a super depth of field optical microscope for detection, the cross-sectional shape of diamond microchannels processed using a galvanometer direct machining method is triangular, with an edge unilateral taper of 62°. The cross-sectional shape of diamond microchannels processed using a five axis attitude alternating machining method is ladder shaped, with a maximum edge unilateral taper of 88°, approaching a vertical state of 90°. As the width of microchannels increases, the unilateral taper value increases. By using a confocal microscope, the roughness of diamond microchannels processed using a galvanometer direct machining method is Ra0.88, and the optimal roughness of diamond microchannels processed using a five axis attitude alternating machining method is Ra0.29. The use of five-axis attitude alternating machining method is superior to the use of galvanometer direct machining in terms of unilateral taper and roughness. Finally, diamond rectangular microchannels were prepared using a five axis attitude alternating machining method, with a maximum aspect ratio of 10.7:1 and a maximum depth of 1.072mm. © COPYRIGHT SPIE. Downloading of the abstract is permitted for personal use only.
  Accession Number: 20241816027699
• Record 60 of
  
  Title:A Path Planning Method for Collaborative Coverage Monitoring in Urban Scenarios
  
  Author(s):Xu, Shufang(1,2); Zhou, Ziyun(1); Liu, Haiyun(1); Zhang, Xuejie(3); Li, Jianni(1); Gao, Hongmin(1)
  Source: Remote Sensing  Volume: 16  Issue: 7  DOI: 10.3390/rs16071152  Published: April 2024  
  Abstract:In recent years, unmanned aerial vehicles (UAVs) have become a popular and cost-effective technology in urban scenarios, encompassing applications such as material transportation, aerial photography, remote sensing, and disaster relief. However, the execution of prolonged tasks poses a heightened challenge owing to the constrained endurance of UAVs. This paper proposes a model to accurately represent urban scenarios and an unmanned system. Restricted zones, no-fly zones, and building obstructions to the detection range are introduced to make sure the model is realistic enough. We also introduced an unmanned ground vehicle (UGV) into the model to solve the endurance of the UAVs in this long-time task scenario. The UGV and UAVs constituted a heterogeneous unmanned system to collaboratively solve the path-planning problem in the model. Building upon this model, this paper designs a Three-stage Alternating Optimization Algorithm (TAOA), involving two crucial steps of prediction and rolling optimization. A three-stage scheme is introduced to rolling optimization to effectively address the complex optimization process for the unmanned system. Finally, the TAOA was experimentally validated in both synthetic scenarios and scenarios modeled based on a real-world location to demonstrate their reliability. The experiments conducted in the synthetic scenarios aimed to assess the algorithm under hypothetical conditions, while the experiments in the scenarios based on real-world locations provided a practical evaluation of the proposed methods in more complex and authentic environments. The consistent performance observed across these experiments underscores the robustness and effectiveness of the proposed approaches, supporting their potential applicability in various real-world scenarios. © 2024 by the authors.
  Accession Number: 20241615917025