2024

• Record 73 of
  
  Title:Phase correction strategy based on structured light fringe projection profilometry
  
  Author(s):Cao, Hongyan(1,2); Qiao, Dayong(1,2); Yang, Di(3)
  Source: Optics Express  Volume: 32  Issue: 3  DOI: 10.1364/OE.513572  Published: January 29, 2024  
  Abstract:Fringe projection profilometry based on structured light has been widely used in 3-D vision due to its advantages of simple structure, good robustness, and high speed. The principle of this technique is to project multiple orders of stripes on the object, and the camera captures the deformed stripe map. Phase unwrapping and depth map calculation are important steps. Still, in actual situations, phase ambiguity is prone to occur at the edges of the object. In this paper, an adaptive phase segmentation and correction (APSC) method after phase unwrapping is proposed. In order to effectively distinguish the stable area and unstable area of the phase, a boundary identification method is proposed to obtain the structural mask of the phase. A phase compensation method is proposed to improve the phase accuracy. Finally, we obtain the 3-D reconstruction result based on the corrected phase. Specific experimental results verify the feasibility and effectiveness of this method. © 2024 Optica Publishing Group under the terms of the Optica Open Access Publishing Agreement.
  Accession Number: 20240615499844
• Record 74 of
  
  Title:Research on the Effect of Vibrational Micro-Displacement of an Astronomical Camera on Detector Imaging
  
  Author(s):Liu, Bin(1); Guan, Shouxin(1); Wang, Feicheng(1); Zhang, Xiaoming(2); Yu, Tao(1); Wei, Ruyi(3,4,5)
  Source: Sensors  Volume: 24  Issue: 3  DOI: 10.3390/s24031025  Published: February 2024  
  Abstract:Scientific-grade cameras are frequently employed in industries such as spectral imaging technology, aircraft, medical detection, and astronomy, and are characterized by high precision, high quality, fast speed, and high sensitivity. Especially in the field of astronomy, obtaining information about faint light often requires long exposure with high-resolution cameras, which means that any external factors can cause the camera to become unstable and result in increased errors in the detection results. This paper aims to investigate the effect of displacement introduced by various vibration factors on the imaging of an astronomical camera during long exposure. The sources of vibration are divided into external vibration and internal vibration. External vibration mainly includes environmental vibration and resonance effects, while internal vibration mainly refers to the vibration caused by the force generated by the refrigeration module inside the camera during the working process of the camera. The cooling module is divided into water-cooled and air-cooled modes. Through the displacement and vibration experiments conducted on the camera, it is proven that the air-cooled mode will cause the camera to produce greater displacement changes relative to the water-cooled mode, leading to blurring of the imaging results and lowering the accuracy of astronomical detection. This paper compares the effects of displacement produced by two methods, fan cooling and water-circulation cooling, and proposes improvements to minimize the displacement variations in the camera and improve the imaging quality. This study provides a reference basis for the design of astronomical detection instruments and for determining the vibration source of cameras, which helps to promote the further development of astronomical detection. © 2024 by the authors.
  Accession Number: 20240715548318
• Record 75 of
  
  Title:A neighbourhood feature-based local binary pattern for texture classification
  
  Author(s):Lan, Shaokun(1); Li, Jie(1); Hu, Shiqi(2); Fan, Hongcheng(3); Pan, Zhibin(1,4)
  Source: Visual Computer  Volume: 40  Issue: 5  DOI: 10.1007/s00371-023-03041-3  Published: May 2024  
  Abstract:The CNN framework has gained widespread attention in texture feature analysis; however, handcrafted features still remain advantageous if computational cost needs to take precedence and in cases where textures are easily extracted with few intra-class variation. Among the handcrafted features, the local binary pattern (LBP) is extensively applied for analysing texture due to its robustness and low computational complexity. However, in local difference vector, it only utilizes the sign component, resulting in unsatisfactory classification capability. To improve classification performance, most LBP variants employ multi-feature fusion. Nevertheless, this can lead to redundant and low-discriminative sub-features and high computational complexity. To address these issues, we propose the neighbourhood feature-based local binary pattern (NF-LBP). Inspired by gradient’s definition, we extract the neighbourhood feature in a local region by simply using the first-order difference and 2-norm. Next, we introduce the neighbourhood feature (NF) pattern to describe intensity changes in the neighbourhood. Finally, we combine the NF pattern with the local sign component and the centre pixel component to create the NF-LBP descriptor. This approach provides better complementary texture information to traditional local sign pattern and is less sensitive to noise. Additionally, we use an adaptive local threshold in the encoding scheme. Our experimental results of classification accuracy and F1 score on five texture databases demonstrate that our proposed NF-LBP method attains outstanding texture classification performance, outperforming existing state-of-the-art approaches. Furthermore, extensive experimental results reveal that NF-LBP is strongly robust to Gaussian noise and salt-and-pepper noise. © The Author(s), under exclusive licence to Springer-Verlag GmbH Germany, part of Springer Nature 2023. corrected publication 2023.
  Accession Number: 20233414605121
• Record 76 of
  
  Title:Electron vortices generation of photoelectron of H 2 + by counter-rotating circularly polarized attosecond pulses
  
  Author(s):Yang, Haojing(1); Liu, Xiaoyu(1); Zhu, Fengzheng(2); Jiao, Liguang(3,4); Liu, Aihua(1,5)
  Source: Chinese Physics B  Volume: 33  Issue: 1  DOI: 10.1088/1674-1056/ad011a  Published: January 1, 2024  
  Abstract:Molecular-frame photoelectron momentum distributions (MF-PMDs) of an H 2 + molecule ion in the presence of a pair of counter-rotating circularly polarized attosecond extreme ultraviolet laser pulses is studied by numerically solving the two-dimensional time-dependent Schrödinger equation within the frozen-nuclei approximation. At small time delay, our simulations show that the electron vortex structure is sensitive to the time delay and relative phase between the counter-rotating pulses when they are partially overlapped. By adjusting time delay and relative phase, we have the ability to manipulate the MF-PMDs and the appearance of spiral arms. We further show that the internuclear distance can affect the spiral vortices due to its different transition cross sections in the parallel and perpendicular geometries. The lowest-order perturbation theory is employed to interpret these phenomena qualitatively. It is concluded that the internuclear distance-dependent transition cross sections and the confinement effect in diatomic molecules are responsible for the variation of vortex structures in the MF-PMDs. © 2024 Chinese Physical Society and IOP Publishing Ltd
  Accession Number: 20240515465957
• Record 77 of
  
  Title:FPM-WSI: Fourier ptychographic whole slide imaging via feature-domain backdiffraction
  
  Author(s):Zhang, Shuhe(1,2,3); Wang, Aiye(1,4); Xu, Jinghao(1,4); Feng, Tianci(1,4); Zhou, Jinhua(3); Pan, An(1,4)
  Source: arXiv  Volume:   Issue:   DOI: 10.48550/arXiv.2402.18270  Published: February 28, 2024  
  Abstract:Fourier ptychographic microscopy (FPM), characterized by high-throughput computational imaging, theoretically provides a cunning solution to the trade-off between spatial resolution and field of view (FOV), which has a promising prospect in the application of digital pathology. However, block reconstruction and then stitching has currently become an unavoidable procedure due to vignetting effects. The stitched image tends to present color inconsistency in different image segments, or even stitching artifacts. Consequently, the advantages of FPM are not as pronounced when compared to the conventional scanning-and-stitching schemes widely employed in whole slide imaging (WSI) systems. This obstacle significantly impedes the profound advancement and practical implementation of FPM, explaining why, despite a decade of development, FPM has not gained widespread recognition in the field of biomedicine. In response, we reported a computational framework based on feature-domain backdiffraction to realize full-FOV, stitching-free FPM reconstruction. Different from conventional algorithms that establish the loss function in the image domain, our method formulates it in the feature domain, where effective information of images is extracted by a feature extractor to bypass the vignetting effect. The feature-domain error between predicted images based on estimation of model parameters and practically captured images is then digitally diffracted back through the optical system for complex amplitude reconstruction and aberration compensation. Through massive simulations and experiments, the method presents effective elimination of vignetting artifacts, and reduces the requirement of precise knowledge of illumination positions. We also found its great potential to recover the data with a lower overlapping rate of spectrum and to realize automatic blind-digital refocusing without a prior defocus distance. Furthermore, to the best of our knowledge, we firstly demonstrated application of FPM on a WSI system, termed FPM-WSI. This platform enables full-color, high-throughput imaging (4.7 mm diameter FOV, 336 nm half-pitch resolution with blue channel illumination) without blocking-and-stitching procedures for a batch of 4 slides. The platform also possesses autofocusing, shifting and regional recognition of slides that are completed by additional automatic mechanical hardware, and the acquisition time for a single slide is less than 4 s. In addition, we provide a user-friendly operation interface to facilitate the workflow, and alternative colorization schemes to choose from. The impact of the reported platform, with advantages of high-quality, high-speed imaging and low cost, will be far-reaching and desired in many fields of biomedical research, as well as in clinical applications. © 2024, CC BY-NC-SA.
  Accession Number: 20240098566
• Record 78 of
  
  Title:Theoretical derivation and application of empirical Harvey scatter model
  
  Author(s):Ma, Zhanpeng(1,2); Wang, Hu(1,2,3); Chen, Qinfang(1,2); Xue, Yaoke(1,2,4,5); Yan, Haoyu(1,2,3); Liu, Jiawen(1,2,3)
  Source: Optics Express  Volume: 32  Issue: 6  DOI: 10.1364/OE.519414  Published: March 11, 2024  
  Abstract:Starting from the Rayleigh-Rice perturbation theory, this paper derives the empirical Harvey scatter model and ABg scatter model applied extensively in optical analysis software packages and verifies the shift-invariant behavior of the scattered radiance in direction cosine space. Using data obtained from multi-wavelength laser scatterometer on carbon nanotube black coating and pineblack coating, we establish the polynomial model based on the sine of the scattering angle plus the sine of the specular reflection angle, i.e., sin θs+sin θ0 and the dual-Harvey model based on sin θs-sin θ0 , respectively. The models are in good accordance with the experimental data and further extend the valid range of empirical models. © 2024 Optica Publishing Group under the terms of the Optica Open Access Publishing Agreement.
  Accession Number: 20241215761907
• Record 79 of
  
  Title:Snapshot compressive imaging at 855 million frames per second for aluminium planar wire array Z-pinch
  
  Author(s):Yao, Zhiming(1); Ji, Chao(2); Sheng, Liang(1); Song, Yan(1); Liu, Zhen(1); Han, Changcai(1); Zhou, Haoyu(1,3); Duan, Baojun(1); Li, Yang(1); Hei, Dongwei(1); Tian, Jinshou(2); Xue, Yanhua(2)
  Source: Optics Express  Volume: 32  Issue: 4  DOI: 10.1364/OE.512450  Published: February 12, 2024  
  Abstract:This paper present a novel, integrated compressed ultrafast photography system for comprehensive measurement of the aluminium planar wire array Z-Pinch evolution process. The system incorporates a large array streak camera and embedded encoding to improve the signal-to-noise ratio. Based on the "QiangGuang-I" pulsed power facility, we recorded the complete continuous 2D implosion process of planar wire array Z-Pinch for the first time. Our results contribute valuable understanding of imploding plasma instabilities and offer direction for the optimization of Z-Pinch facilities. © 2024 Optica Publishing Group.
  Accession Number: 20240815569617
• Record 80 of
  
  Title:Design of a refractive-metasurface hybrid annular aperture folded optical system
  
  Author(s):Mao, Shan(1,2); Lai, Tao(1); Yuan, Peiqi(1); Wang, Junzhe(1); Zhao, Jianlin(1)
  Source: Optics Express  Volume: 32  Issue: 7  DOI: 10.1364/OE.517002  Published: March 25, 2024  
  Abstract:Folded lenses offer advantages in terms of lightness and thinness, but they have limitations when it comes to correcting aberrations. In this paper, we propose a novel approach to address this issue by incorporating metasurfaces in the design of folded optical systems. Specifically, a folded refractive-metasurface hybrid annular aperture folded lens (AFL) is introduced. The structural characteristics of the AFL imaging system are analyzed to investigate the blocking ratio, thickness, and light collection capability of the ring aperture system. Additionally, a hybrid optical integration design using Zemax software is proposed for the metasurfaces. A quadruple-folded AFL working in the mid-infrared waveband is then designed. The superstructure surface is analyzed, and its processability is discussed. The results demonstrate that the reflective-metasurface hybrid AFL significantly improves the imaging quality of this type of optical system while meeting the required design accuracy. © 2024 Optica Publishing Group under the terms of the Optica Open Access Publishing Agreement.
  Accession Number: 20241415835164
• Record 81 of
  
  Title:Study on the construction of twisted cosine partially coherent beams and their propagation characteristics
  
  Author(s):Zhang, Shaohua(1); Zhou, Yuan(2,3); Chai, Yutong(1); Qu, Jun(1)
  Source: AIP Advances  Volume: 14  Issue: 2  DOI: 10.1063/5.0186514  Published: February 1, 2024  
  Abstract:We propose a novel Schell model source for generating twisted partially coherent beams with an initial radius of curvature, which is called a twisted flat-topped cosine Gaussian Schell-model (TFCGSM) source. The TFCGSM beam comprises a wavefront phase and a flat-top structure, with the source degree of coherence determined by two cosine functions. Based on the Huygens-Fresnel principle, the general analytical expression of the cross-spectral density function of the TFCGSM beam propagating through the paraxial ABCD optical system is derived, and then its propagation properties are studied. The results show that the conversion of the array of the beam and the non-uniform structure can be realized by adjusting the parameters in the source plane. As the propagation distance of the TFCGSM beam increases, it rotates around the axis and increases the intensity of the array distribution. Surprisingly, the initial radius of curvature can cause the beam to rotate. The unique shape and properties of the TFCGSM beam create new possibilities for optical communication and enhanced optical functions. © 2024 Author(s).
  Accession Number: 20240815596823
• Record 82 of
  
  Title:CMID: Crossmodal Image Denoising via Pixel-Wise Deep Reinforcement Learning
  
  Author(s):Guo, Yi(1,2,3); Gao, Yuanhang(4); Hu, Bingliang(1,3); Qian, Xueming(2); Liang, Dong(4)
  Source: Sensors  Volume: 24  Issue: 1  DOI: 10.3390/s24010042  Published: January 2024  
  Abstract:Removing noise from acquired images is a crucial step in various image processing and computer vision tasks. However, the existing methods primarily focus on removing specific noise and ignore the ability to work across modalities, resulting in limited generalization performance. Inspired by the iterative procedure of image processing used by professionals, we propose a pixel-wise crossmodal image-denoising method based on deep reinforcement learning to effectively handle noise across modalities. We proposed a similarity reward to help teach an optimal action sequence to model the step-wise nature of the human processing process explicitly. In addition, We designed an action set capable of handling multiple types of noise to construct the action space, thereby achieving successful crossmodal denoising. Extensive experiments against state-of-the-art methods on publicly available RGB, infrared, and terahertz datasets demonstrate the superiority of our method in crossmodal image denoising. © 2023 by the authors.
  Accession Number: 20240215372894
• Record 83 of
  
  Title:Efficient Power Scaling of Broad-Area Laser Diodes from 915 to 1064 nm
  
  Author(s):Yang, Guowen(1,2,3); Liu, Yuxian(2,3); Zhao, Yuliang(2,3); Lan, Yu(2,3); Zhao, Yongming(1); Tang, Song(1); Wu, Wenjun(1); Yao, Zhonghui(1); Li, Ying(1); Di, Jiuwen(1); Jixiang, Lin(1); Demir, Abdullah(4)
  Source: Proceedings of SPIE - The International Society for Optical Engineering  Volume: 12867  Issue:   DOI: 10.1117/12.3002642  Published: 2024  
  Abstract:Our primary goal is to significantly enhance the output power of broad-area laser diodes (LDs) for improved cost-effectiveness of laser systems and broaden their applications in various fields. To achieve this, we implemented an epitaxial design with low internal optical loss and high internal efficiency in agreement with our simulations. We present comprehensive results of high-power single-emitter and bar LDs spanning wavelengths from 915 to 1064 nm. To demonstrate power scaling in single emitter LDs, we utilized waveguide widths from 100 to 500 µm, achieving a continuous-wave (CW) maximum output power of 74 W at 976 nm under room temperature conditions, limited by the heatsink temperature control. We also build fiber-coupled modules with single-emitters operating at 1.6 kW. Employing the same epitaxial structure in 1-cm wide laser bars, we demonstrated 976 nm laser bars operated at 100 A CW with 113 W output and a high efficiency of 72.9% at room temperature. Additionally, we achieved 500 W room-temperature CW laser bars at 940 nm. For long wavelength designs at 1064 nm, 500 W output was obtained in quasi-continuous-wave (QCW) operating laser bars. Our results represent significant advancements in obtaining high power and efficient LDs across a broad wavelength range and configuration. © 2024 SPIE.
  Accession Number: 20241615941127
• Record 84 of
  
  Title:High-performance reconstruction method combining total variation with a video denoiser for compressed ultrafast imaging
  
  Author(s):Pei, Chengquan(1); Day-Uei Li, David(2); Shen, Qian(3); Zhang, Shian(4); Qi, Dalong(4); Jin, Chengzhi(4); Dong, Le(1)
  Source: Applied Optics  Volume: 63  Issue: 8  DOI: 10.1364/AO.506058  Published: March 10, 2024  
  Abstract:Compressed ultrafast photography (CUP) is a novel two-dimensional (2D) imaging technique to capture ultrafast dynamic scenes. Effective image reconstruction is essential inCUPsystems.However, existing reconstruction algorithms mostly rely on image priors and complex parameter spaces. Therefore, in general, they are time-consuming and result in poor imaging quality, which limits their practical applications. In this paper, we propose a novel reconstruction algorithm, to the best of our knowledge, named plug-in-plug-fast deep video denoising net-total variation (PnP-TV-FastDVDnet), which exploits an image’s spatial features and correlation features in the temporal dimension. Therefore, it offers higher-quality images than those in previously reported methods. First, we built a forward mathematical model of the CUP, and the closed-formsolution of the three suboptimization problems was derived according to plug-in and plug-out frames. Secondly, we used an advanced video denoising algorithm based on a neural network named FastDVDnet to solve the denoising problem. The peak signal-to-noise ratio (PSNR) and structural similarity index measure (SSIM) are improved on actual CUP data compared with traditional algorithms. On benchmark and real CUP datasets, the proposed method shows the comparable visual results while reducing the running time by96% over state-of-the-art algorithms. © 2024 Optica Publishing Group.
  Accession Number: 20241215786117