2024

• Record 181 of
  
  Title:Laser-guided anisotropic etching for precision machining of micro-engineered glass components
  
  Author(s):Li, Jun(1); Zhong, Shuai(1); Huang, Jiaxu(1); Qiu, Pei(1); Wang, Pu(1,2); Li, Hui(1); Qin, Chu(3); Miao, Duo(1); Xu, Shaolin(1)
  Source:International Journal of Machine Tools and Manufacture
  Volume: 198  Issue:   DOI: 10.1016/j.ijmachtools.2024.104152  Published: May 2024  
  Abstract:Micro-engineered glass components play a vital role in various domains, but their full potential remains untapped due to the lack of easily accessible high-precision machining methods for customizable microstructure. Our discovery of a new phenomenon, where laser-modified regions break the rule of inherently isotropic glass etching and regulate a directional anisotropic etching along modified tracks, has led to the development of a laser-guided anisotropic etching (LGAE) method. This method enables crafting precision glass microstructures with sharp features, smooth surfaces, and adjustable shapes and sizes. An ultrafast Bessel beam is utilized to create high aspect-ratio line-shaped modification within the glass. With a higher etching rate than pristine glass, the modified line guides directional anisotropic etching along the modified track, facilitating the formation of a V-shape with an angle altered by the etching ratio. These modified lines can further serve as basic building blocks to interconnect to construct a 3D internal modification region and then guide the glass's overall surface morphology etching evolution, enabling the creation of microstructures featuring designable shapes and adjustable feature sizes. To accurately predict and control the shape of the microstructures, we establish a finite difference etching model that incorporates localized etching rate regulation, validating the robustness and controllability of LGAE. This scalable method has successfully fabricated a 50 μm period micro-pyramid array with high uniformity over a centimeter-scale area, demonstrating its suitability for large-scale manufacturing. The showcased micro-engineered glass components encompass V-groove arrays for fiber alignment, blazed gratings for light modulation, and microchannels with customized trajectories for microfluidic chips. These advancements driven by LGAE can significantly contribute to the progress of glass-based research and industries. © 2024 Elsevier Ltd
  Accession Number: 20241515905919
• Record 182 of
  
  Title:Optimal design of a gravitational wave telescope system for the suppression of stray light
  
  Author(s):Liang, Rong(1,2); Zhou, Xiaojun(1); Xu, Huangrong(1); Wu, Dengshan(1); Li, Chenxi(1); Yu, Weixing(1,2)
  Source:Applied Optics
  Volume: 63  Issue: 8  DOI: 10.1364/AO.502610  Published: March 10, 2024  
  Abstract:For gravitational wave detection, the telescope is required to have an ultra-low wavefront error and ultra-high signal-to-noise ratio, where the power of the stray light should be controlled on the order of less than 10-10. In this work, we propose an alternative stray light suppression method for the optical design of an off-axis telescope with four mirrors by carefully considering the optimal optical paths. The method includes three steps. First, in the period of the optical design, the stray light caused by the tertiary mirror and the quaternary mirror is suppressed by increasing the angle formed by the optical axes of the tertiary mirror and the quaternary mirror and reducing the radius of curvature of the quaternary mirror as much as possible to make sure the optical system provides a beam quality with a wavefront error less than λ/80. Next, the stray light could satisfy the requirement of the order of 10-10 when the level of roughness reaches 0.2 nm, and the pollution of mirrors is controlled at the level of CL100. Finally, traditional stray light suppression methods should also be applied to mechanics, including the use of the optical barrier, baffle tube, and black paint. It can be seen that the field stop can efficiently reduce stray light caused by the secondary mirror by more than 55% in the full field of view. The baffle tube mounted on the position of the exit pupil can reduce the overall stray light energy by 5%, and the difference between the ideal absorber (absorption coefficient is 100%) and the actual black paint (absorption coefficient is 90%) is 3.2%. These simulation results are confirmed by theMonte Carlo method for a stray light analysis. Based on the above results, one can conclude that the geometry structure of the optical design, the quality of mirrors, and the light barrier can greatly improve the stray light suppression ability of the optical system, which is vital when developing a gravitational wave telescope with ultra-lowstray light energy. © 2024 Optica Publishing Group.
  Accession Number: 20241215786774
• Record 183 of
  
  Title:Nonmeasurable Range Elimination of Dispersive Interferometry
  
  Author(s):Huang, Jingsheng(1,5); Du, Wei(1); Wang, Jindong(1,2); Wang, Weiqiang(3); Wang, Yang(2); Li, Duidui(1); Chu, Sai T.(4); Zhang, Wenfu(2); Zhu, Tao(1)
  Source:ACS Photonics
  Volume: 11  Issue: 7  DOI: 10.1021/acsphotonics.4c00475  Published: July 17, 2024  
  Abstract:Dispersive interferometry (DPI) stands as a formidable method in both scientific and industrial realms, offering the capability for numerous measurement scenarios with remarkable accuracy over extensive ranges. The advent of on-chip soliton microcombs (SMCs) boasting a high repetition rate illuminates a promising pathway toward measurements free from dead zones. However, its application scenarios are considerably constrained by the nonmeasurable range (NMR)─the region proximate to the measurement period’s extreme points, which is circumscribed by the fast Fourier transform (FFT) steps and symmetry of the data calculation procedure. Here, we introduce an NMR elimination method that refines the DPI structure by engendering an asymmetric interference spectrum. Furthermore, a phase saltation tracking (PST) method for demodulating is devised, enabling measurements without NMR. Both simulation analyses and experimental outcomes affirm that our proposed method significantly enhances the performance of the DPI system by eliminating NMR and improving measurement precision. The Allan deviation of our method consistently remains lower than the DPI measurement results under identical conditions over an average time of 125 s, achieving 7.43 nm at 125 s. This method holds promising potential for application in emerging fields such as optical coherence tomography (OCT), long-distance ranging, and precision light detection and ranging (LIDAR). © 2024 American Chemical Society.
  Accession Number: 20242816662390
• Record 184 of
  
  Title:Automatic detection of face mask wearing based on polarization imaging
  
  Author(s):Li, Bosong(1); Li, Yahong(1); Li, Kexian(1); Fu, Yuegang(2); Ouyang, Mingzhao(2); Jia, Wentao(3)
  Source:Optics Express
  Volume: 32  Issue: 20  DOI: 10.1364/OE.528929  Published: September 23, 2024  
  Abstract:Amidst the global health crisis sparked by the coronavirus pandemic, the proliferation of respiratory illnesses has captured worldwide attention. An increasing number of individuals wear masks to mitigate the risk of viral transmission. This trend has posed a critical challenge for the development of automatic face mask wearing detection systems. In response, this paper proposed what we believe is a novel face mask wearing detection framework DOLP-YOLOv5, which innovatively employs polarization imaging to enhance the detection of face mask by leveraging the unique characteristics of mask surfaces. For extracting essential semantic details of masks and diminish the impact of background noise, the lightweight shuffle attention (SA) mechanism is integrated in the backbone. Further, a Content-Aware Bidirectional Feature Pyramid Network (CA-BiFPN) is applied for feature fusion, sufficiently integrating the information at each stage and improving the ability of the feature presentation. Moreover, Focal-EIoU loss is utilized for the bounding box regression to improve the accuracy and efficiency of detection. Benchmark evaluation is performed on the self-constructed polarization face mask (PFM) dataset compared with five other mainstream algorithms. The mAP50-95 of DOLP-YOLOv5 reached 63.5%, with 3.08% and 4.44% improvements over the YOLOv8s and YOLOv9s, and achieved a response speed of 384.6f/s. This research not only demonstrates the superiority of DOLP-YOLOv5 in face mask wearing detection, but also has certain reference significance for other detection of polarization imaging. © 2024 Optica Publishing Group under the terms of the Optica Open Access Publishing Agreement.
  Accession Number: 20244017128299
• Record 185 of
  
  Title:Analysis of InGaAs/InP Single Photon Avalanche Diodes With Multiplication Width in Sub-Micron
  
  Author(s):Qiao, Kai(1,2,3); Chang, Yu(1); Xu, Zefang(1,3); Yin, Fei(1); Liu, Liyu(1,3); Wang, Jieying(1); Su, Chang(1,3); Xu, Linmeng(1,3); Fang, Mengyan(1,3); Liu, Chunliang(2); Tian, Jinshou(1); Wang, Xing(1)
  Source:IEEE Journal of Quantum Electronics
  Volume: 60  Issue: 4  DOI: 10.1109/JQE.2024.3399176  Published: August 1, 2024  
  Abstract:InGaAs/InP single-photon avalanche photodiodes (SPADs) is capable of detecting single-photon in the near-infrared spectrum for applications such as quantum communication, fluorescence lifetime imaging, and Light detection and ranging(LIDAR). The effect of multiplication layer width on the performance of SPADs in both linear and Geiger mode have been theoretically studied. Three-types of InGaAs/InP planer SPADs with different multiplication width are fabricated and evaluated. The results of this study suggest that modifying the width of the multiplication layer can regulate the breakdown voltage, punch-through voltage, and dark current of the device. It is found that the measured time jitter is decreasing with the reduction of the width of the multiplication region. These characteristics can be used to optimize the temporal resolution of SPADs device. © 1965-2012 IEEE.
  Accession Number: 20242016094811
• Record 186 of
  
  Title:Multi-Grained and Confidence-Aware Multiple Instance Network for Infrared Target Detection
  
  Author(s):Chen, Weining(1,2,3); Yang, Hongtao(2); Chang, Sansan(2,3); Chen, Yunzhi(4); Wang, Xinlin(5); Chen, Yaohong(2,3)
  Source:IEEE Transactions on Geoscience and Remote Sensing
  Volume: 62  Issue:   DOI: 10.1109/TGRS.2024.3422924  Published: 2024  
  Abstract:Weakly supervised object detection (WSOD) methods that trains an object detection network using image-level labels has attracted much attention due to its cost-effective annotation and broad applied requirement. However, applying such weak label to detect targets in infrared images is not trivial due to the less discriminative target information and interference of complex backgrounds. This article proposes a multi-grained and confidence-aware multiple instance network (MCMIN) to detect infrared targets given the imprecise labels. The multiscale multi-grained feature extraction module is designed to capture discriminative features from different receptive fields for dim-small targets. The hierarchical multiple instance target detection module first applies L1-sparsity regularization to encourage the model generate reliable pseudo ground truth (GT), and then leverages the confidence-aware instance adaptive weighting strategy to refine proposals with particular emphasis, achieving more accurate target detection. The experimental results on two infrared target detection datasets illustrate that the proposed MCMIN outperforms other state-of-the-art WSOD methods with higher average precision (AP). The proposed approach decreases the false alarms. © 1980-2012 IEEE.
  Accession Number: 20242816673755
• Record 187 of
  
  Title:Low-loss nodeless hollow-core anti-resonant soft glass fiber for the 4 µm mid-infrared spectral range
  
  Author(s):Chang, Yanjie(1,2); Zhang, Hao(1,2); Yantao, X.U.(1,2); Chengzhen, L.I.U.(1,2); Xiao, Xusheng(1,2); Guo, Haitao(1,2,3)
  Source:Optics Express
  Volume: 32  Issue: 13  DOI: 10.1364/OE.528551  Published: June 17, 2024  
  Abstract:Infrared soft glass hollow-core anti-resonant fibers (HC-ARF) with low loss, excellent mode purity, and robust high-power transmission capabilities have vast potential in mid-infrared high-power laser transmission and biomedical fields. Despite this, the fabrication of these fibers still faces formidable challenges, coupled with an incomplete understanding of the transmission characteristics, thereby amplifying the value of further exploration. In this paper, we fabricate a six-cell nodeless infrared HC-ARF originating from purified sulfide glass, synthesized using a meticulous "stack-and-draw" method and dual-gas-path pressure control method. Notably, we experimentally validate the theoretical performance expectations of this fiber. The fiber exhibits outstanding transmission capabilities and optical transmission quality, characterized by a recorded loss of 0.56 dB/m at 4.79 µm. This is already comparable to traditional step-index sulfide fibers, fully demonstrating its tremendous research value and application potential. Our work has successfully fabricated the lowest loss anti-resonant fiber on record in the mid-infrared field, propelling the development of sulfide HC-ARFs into a new phase and laying a solid foundation for the realization of fiber applications in laser transmission and the biomedical field. © 2024 Optica Publishing Group under the terms of the Optica Open Access Publishing Agreement.
  Accession Number: 20242616354102
• Record 188 of
  
  Title:Design and fabrication of a tellurite hollow-core anti-resonant fiber for mid-infrared applications
  
  Author(s):Zhu, Jun(1,2); Feng, Shaohua(1,2); Liu, Chengzhen(1,2); Cai, Liyang(1,2); Xu, Yantao(1,2); Xiao, Xusheng(1,2); Guo, Haitao(1,2,3)
  Source:Optics Express
  Volume: 32  Issue: 8  DOI: 10.1364/OE.519034  Published: April 8, 2024  
  Abstract:The hollow core anti-resonant fibers (HC-ARFs) based on soft glass are in high demand for 3-6 µm laser delivery. A HC-ARF based on tellurite glass with 6 touching capillaries as cladding was designed and fabricated for the first time, to the best of our knowledge. A relatively low loss of 3.75 dB/m at 4.45 µm was realized in it. The effects of capillary number, core diameter, wall thickness of capillary, and material absorption loss on the loss of the HC-ARF were analyzed by the numerically simulation. The output beam quality was measured and the influence of bending on the fiber loss was discussed. The results of numerical simulation suggested that the theoretical loss of the prepared fiber can be reduced to 0.1 dB/m, indicating that tellurite HC-ARFs have great potential for mid-infrared laser applications. © 2024 Optica Publishing Group under the terms of the Optica Open Access Publishing Agreement.
  Accession Number: 20241615913638
• Record 189 of
  
  Title:Lightweight and optimized U-frame design for space-borne two-dimensional turntable
  
  Author(s):Wei, Yu-Xuan(1,2,3); Wang, Zhen-Yu(1,3); Li, Zhi-Guo(1,3); Huang, Le-Hong(1,2,3); Yang, Kai(1,2); Ma, Yu-Bao(1,2)
  Source:Chinese Optics
  Volume: 17  Issue: 4  DOI: 10.37188/CO.2023-0227  Published: July 2024  
  Abstract:Space-borne two-dimensional turntables are the main bearing mechanism of space cameras and other optoelectronic equipment, and the U-frame is the key supporting part of these turntables. In order to optimize the structure and lightweight design of the U-frame of the two-dimensional turntable and to develop a lightweight two-dimensional turntable with a high load-bearing ratio, we design a U-frame for the space two-dimensional turntable based on Carbon Fiber Reinforce Plastics (CFRP). First, a variable cross-section tubular structure U-frame was designed using carbon fiber composites instead of titanium alloy material considering the manufacturability. Then, according to the finite element modeling method based on the lay-up process, the carbon fiber U-frame was subjected to finite element modeling and simulation analysis. Then, a prototype U-frame was fabricated, and modal tests verified the accuracy of the finite element model. Finally, a three-level optimization method combining theoretical analysis, genetic algorithm, and the finite element method was proposed to optimize the design of carbon fiber U-frame ply angle, ply thickness, and ply sequence. The results indicate that the vibration patterns of the U-frame obtained from the modal test and simulation are identical and that the frequency difference is less than 5%. The initial design of the carbon fiber U-frame is 45.7% lighter than the titanium U-frame. Through the secondary optimization of the composite layup, the U-frame is further reduced in weight by 13.8%. Additionally, the intrinsic frequency of the U-frame is improved by 10.14%. It can be concluded that the composite modeling and optimization methods used in this paper are correct, and the designed carbon fiber U-frame meets the lightweight design requirements of space-born two-dimensional turntable. © 2024 Editorial Office of Chinese Optics. All rights reserved.
  Accession Number: 20243116787564
• Record 190 of
  
  Title:High Accurate and Efficient 3D Network for Image Reconstruction of Diffractive-Based Computational Spectral Imaging
  
  Author(s):Fan, Hao(1,2); Li, Chenxi(1); Xu, Huangrong(1); Zhao, Lvrong(1,2); Zhang, Xuming(3); Jiang, Heng(3); Yu, Weixing(1,2)
  Source:IEEE Access
  Volume: 12  Issue:   DOI: 10.1109/ACCESS.2024.3451560  Published: 2024  
  Abstract:Diffractive optical imaging spectroscopy as a promising miniaturized and high throughput portable spectral imaging technique suffers from the problem of low precision and slow speed, which limits its wide use in various applications. To reconstruct the diffractive spectral image more accurately and fast, a three-dimensional spectrum recovery algorithm is proposed in this paper. The algorithm takes advantage of a neural network for image reconstruction which consists of a U-Net architecture with 3D convolutional layers to improve the processing precision and speed. Numerical experiments are conducted to prove its effectiveness. It is shown that the mean peak signal-to-noise ratio (MPSNR) of the recovered image relative to the original image is improved by 1.8 dB in comparison to other traditional methods. In addition, the obtained mean structural similarity (MSSIM) of 0.91 meets the standard of discrimination to human eyes. Moreover, the algorithm runs in just 0.36 s, which is faster than other traditional methods. 3D convolutional networks play a critical role in performance improvement. Improvements in processing speed and accuracy have greatly benefited the realization and application of diffractive optical imaging spectroscopy. The new algorithm with high accuracy and fast speed has a great potential application in diffraction lens spectroscopy and paves a new way for emerging more portable spectral imaging technique. © 2013 IEEE.
  Accession Number: 20243717031297
• Record 191 of
  
  Title:An innovative 16-bit projection display based on quaternary hybrid light modulation
  
  Author(s):Pan, Yue(1,2); Cao, Yajie(1); Xu, Liang(3); Hu, Motong(1); Jiang, Qing(4); Li, Shuqin(4); Lu, Xiaowei(1)
  Source:Optics and Lasers in Engineering
  Volume: 178  Issue:   DOI: 10.1016/j.optlaseng.2024.108171  Published: July 2024  
  Abstract:Conventional spatial light modulators (SLM) can only be used for projecting 8-bit or 10-bit images at normal frame rate. Therefore, commercial high dynamic range (HDR) displays typically focus on boosting the contrast while neglecting to raise the bit-depth. Existing methods for high bit-depth display generally rely on stacking two SLMs to modulate the outgoing beam twice, namely multiplicative modulation, resulting in many troubles such as low optical efficiency, difficulty in pixel-level alignment, and complex image rendering algorithm. In this paper, an innovative quaternary hybrid light modulation (QHLM) based projection display is proposed and realized. By illuminating two parallel digital micro-mirror devices (DMDs) with different light intensities, the quaternary digit-planes (QDs) with four gray levels are able to be modulated rapidly. Aiming at this ability, the quaternary pulse width modulation (QPWM) is incorporated with the quaternary light-intensity modulation (QLM) to fundamentally improve the modulation efficiency compared to the binary light modulation mode. Furthermore, the quaternary digit-plane decomposition (QDD) based image splitting algorithm is adopted to split a high bit-depth image into two images that drive two DMDs respectively. The prototype is designed and built to verify the feasibility of the QHLM based projection display. The experimental results demonstrate that the prototype can project 16-bit images at 220 fps. Through additive modulation of two DMDs in parallel, the QHLM entirely avoids the drawbacks of multiplicative modulation. As a completely different technology, the QHLM has a great potential for HDR projection applications. © 2024 Elsevier Ltd
  Accession Number: 20241215789270
• Record 192 of
  
  Title:Analysis of Imaging Limit Capability for Natural Rendezvous of Low Earth Orbit Debris
  
  Author(s):Li, Yaru(1,2,3); Zhou, Liang(1,3); Liu, Zhaohui(1,3); She, Wenji(1,3); Cui, Kai(1,2,3)
  Source:Guangzi Xuebao/Acta Photonica Sinica
  Volume: 53  Issue: 8  DOI: 10.3788/gzxb20245308.0811003  Published: August 2024  
  Abstract:In order to achieve precise attitude monitoring of large-sized space debris，the spatial resolution of cameras is continuously improving. However，this improvement leads to an increasing blurring effect caused by relative motion during exposure time. It is particularly important to research on how to balance camera resolution and the issue of image blur caused by motion-induced displacement. For low earth orbit natural rendezvous imaging scenarios，changes in the camera's observational angle before and after the rendezvous lead to variations in the position and orientation of the target in the camera line of sight. The image motion generated as a result of this is referred to as intrinsic image motion in the natural rendezvous imaging scenario. This passage establishes the equation for the image plane position through the mapping relationship between the points of space target objects and their corresponding image points. The equation involves the transformation of coordinates in seven different coordinate systems. In theory，taking the derivative of this equation with respect to time yields the instantaneous velocity equation for image motion. However，due to the immense computational complexity of the matrix and numerous parameters involved （including the orbital parameters of the imaging platform and target，spatial resolution of the camera，exposure time，etc.），it is impractical to provide an exact expression for intrinsic image motion. Therefore，we obtain the image plane positions at different time points based on specific orbital and imaging parameters，calculate the intrinsic image motion within the exposure time，and then employ a data fitting method to obtain a model for the intrinsic image motion function. Through analyzing the relative radial velocity of the target with the camera and the displacement of the target along the optical axis at the rendezvous moment，it can be understood that the rotational image motion of the target around the optical axis is a primary factor in intrinsic image motion. Therefore，this intrinsic image motion is directly correlated with the relative rotational angular velocity between the target and the camera，exposure time，angular separation between the target and the camera，and the spatial resolution of the camera. Taking into consideration these influencing factors，this paper calculates the intrinsic image motion for specific imaging orbits and various influencing factors using the image plane position equation. The obtained data is utilized as a training set for fitting the intrinsic image motion function. The fitting correlation coefficient for the training set is 0.99，with a root mean square error of 0.12. Subsequently，intrinsic image motion calculated with different orbital parameters is used as a test set to validate the accuracy of the fitting function. The correlation coefficients for different independent variables are all greater than 0.9，and the root mean square error are all less than 0.2. This indicates that the fitting accuracy of the intrinsic image motion function is high，and the fitting results are reliable. The intrinsic image motion function model reveals that intrinsic image motion is linearly correlated with relative rotational angular velocity，exposure time，and the angular separation between the target and the camera. It is also exponentially correlated with the spatial resolution of the camera. This paper analyzes the impact of this image motion on the modulation transfer function. When the image motion is greater than 0.5 pixels， the modulation transfer function decreases by approximately 10%，failing to meet the overall system design requirements. Therefore，this paper takes an image displacement of 0.5 pixels as the maximum allowable displacement and establishes a constraint on the camera's spatial resolution at the time of natural intersection. This constraint illustrates the relationship between camera resolution and the relative angular velocity，exposure time，and angular separation between the target and the camera under the condition of satisfying the maximum allowable image motion. Taking a specific set of imaging orbits as an example，we demonstrate the method of calculating the maximum resolution of the camera at the rendezvous moment using this constraint condition. We point out that in low earth orbit rendezvous imaging scenarios，even if the spatial camera resolution exceeds this limit，there is no improvement in image quality. This indicates that the constraint condition has a significance for the design of imaging cameras and the selection of exposure parameters. © 2024 Chinese Optical Society. All rights reserved.
  Accession Number: 20243917106310