Pub Date : 2024-09-27DOI: 10.1016/j.optlaseng.2024.108603
Xu Liang, Xinge Qian, Wenhao Li, Wei Wang, Zhaowu Liu
In this paper, a dual-channel dispersive interferometer using femtosecond laser is developed with a reference long optical fiber. The width spectrum of the femtosecond laser is divided into a ranging channel and a monitor channel using a coarse wavelength division multiplexer. The ranging channel uses long fiber to construct an unbalanced interferometer to eliminate measurement dead zone by changing the repetition frequency. The monitor channel can measure the fluctuation of long optical fiber in real-time. The dual-channel interference signal then can be received by one single spectrometer. The optical path drift of the long fiber-based reference path can be synchronously compensated to achieve high-precision ranging. In experiments, a 116 m long optical fiber was compensated to 3 × 10−8 stability for one hour. Compared with a commercial interferometer, the ranging accuracy is better than ±4 μm within a range of 300 mm.
{"title":"Absolute distance measurement without dead zone based on dual-channel dispersive interferometry using the femtosecond laser","authors":"Xu Liang, Xinge Qian, Wenhao Li, Wei Wang, Zhaowu Liu","doi":"10.1016/j.optlaseng.2024.108603","DOIUrl":"10.1016/j.optlaseng.2024.108603","url":null,"abstract":"<div><div>In this paper, a dual-channel dispersive interferometer using femtosecond laser is developed with a reference long optical fiber. The width spectrum of the femtosecond laser is divided into a ranging channel and a monitor channel using a coarse wavelength division multiplexer. The ranging channel uses long fiber to construct an unbalanced interferometer to eliminate measurement dead zone by changing the repetition frequency. The monitor channel can measure the fluctuation of long optical fiber in real-time. The dual-channel interference signal then can be received by one single spectrometer. The optical path drift of the long fiber-based reference path can be synchronously compensated to achieve high-precision ranging. In experiments, a 116 m long optical fiber was compensated to 3 × 10<sup>−8</sup> stability for one hour. Compared with a commercial interferometer, the ranging accuracy is better than ±4 μm within a range of 300 mm.</div></div>","PeriodicalId":49719,"journal":{"name":"Optics and Lasers in Engineering","volume":"184 ","pages":"Article 108603"},"PeriodicalIF":3.5,"publicationDate":"2024-09-27","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142326811","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-09-26DOI: 10.1016/j.optlaseng.2024.108597
Zhengyu Wu , Gang Chen , Shutian Liu , Wei Liu , Dazhao Chi , Bin Gao , Yutong Li , Zhengjun Liu
Lensless imaging systems have gained significant attention recently due to their advantages in terms of reduced size and weight compared to traditional lens-based systems. However, like other imaging methods, lensless imaging encounters challenges in resolving scenes with more details. In this article, we propose a novel four-frame super-resolution method specifically tailored for lensless imaging systems. Our approach shares similarities with previous lensless imaging systems, involving a sensor and a modulation device placed in front of the image sensor. We develop an explicit degradation downsampling model with sub-pixel shifts and provide the solution to corresponding inverse problem, may offering valuable guidance for other super-resolution imaging algorithms based on spatial displacements. By applying random lateral sub-pixel shifts, acquiring four low-resolution (LR) images, and fusing their spatial information, we achieve high-resolution (HR) sensor recordings, enabling super-resolution reconstruction of the imaging scene. Numerical simulations demonstrate approximately an improvement in spatial resolution compared to single-measurement methods. Furthermore, we evaluate the performance of our method across various lensless imaging systems utilizing different masks, validating its versatility and effectiveness in achieving higher resolution outcomes. Experimental results also support our proposed scheme's ability to achieve higher spatial resolution reconstruction in a real system.
{"title":"Four-frame pixel super-resolution method for lensless imaging systems","authors":"Zhengyu Wu , Gang Chen , Shutian Liu , Wei Liu , Dazhao Chi , Bin Gao , Yutong Li , Zhengjun Liu","doi":"10.1016/j.optlaseng.2024.108597","DOIUrl":"10.1016/j.optlaseng.2024.108597","url":null,"abstract":"<div><div>Lensless imaging systems have gained significant attention recently due to their advantages in terms of reduced size and weight compared to traditional lens-based systems. However, like other imaging methods, lensless imaging encounters challenges in resolving scenes with more details. In this article, we propose a novel four-frame super-resolution method specifically tailored for lensless imaging systems. Our approach shares similarities with previous lensless imaging systems, involving a sensor and a modulation device placed in front of the image sensor. We develop an explicit degradation downsampling model with sub-pixel shifts and provide the solution to corresponding inverse problem, may offering valuable guidance for other super-resolution imaging algorithms based on spatial displacements. By applying random lateral sub-pixel shifts, acquiring four low-resolution (LR) images, and fusing their spatial information, we achieve high-resolution (HR) sensor recordings, enabling super-resolution reconstruction of the imaging scene. Numerical simulations demonstrate approximately an improvement in spatial resolution compared to single-measurement methods. Furthermore, we evaluate the performance of our method across various lensless imaging systems utilizing different masks, validating its versatility and effectiveness in achieving higher resolution outcomes. Experimental results also support our proposed scheme's ability to achieve higher spatial resolution reconstruction in a real system.</div></div>","PeriodicalId":49719,"journal":{"name":"Optics and Lasers in Engineering","volume":"184 ","pages":"Article 108597"},"PeriodicalIF":3.5,"publicationDate":"2024-09-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142323009","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-09-26DOI: 10.1016/j.optlaseng.2024.108598
Kaikai Wang , Chao Wang , Qiang Fu , Jianan Liu , Qi Wang , Haodong Shi
This study introduces a novel method for decomposing polarization aberrations. It uses two sets of reduction matrices to decompose the diattenuation and retardance Mueller matrix into five independent reduction coefficients. And then, it uses Zernike polynomials to decompose these coefficients at the exit pupil, thereby providing a method for quantitatively analyzing the polarization aberrations. This method also gives the constraint values of the Zernike term of polarization aberrations during astronomical telescope design. Finally, the effectiveness and correctness of the process are verified by simulation of the actual optical system, pointing out that the D1, D2, D3, and R5 terms need to be calibrated and optimized to ensure polarization accuracy. This method offers a valuable tool and theoretical guidance for the polarization design of high-precision optical systems.
{"title":"The Mueller pupils Reduction-Zernike polynomial decomposition and polarization design criteria for the astronomical telescope system","authors":"Kaikai Wang , Chao Wang , Qiang Fu , Jianan Liu , Qi Wang , Haodong Shi","doi":"10.1016/j.optlaseng.2024.108598","DOIUrl":"10.1016/j.optlaseng.2024.108598","url":null,"abstract":"<div><div>This study introduces a novel method for decomposing polarization aberrations. It uses two sets of reduction matrices to decompose the diattenuation and retardance Mueller matrix into five independent reduction coefficients. And then, it uses Zernike polynomials to decompose these coefficients at the exit pupil, thereby providing a method for quantitatively analyzing the polarization aberrations. This method also gives the constraint values of the Zernike term of polarization aberrations during astronomical telescope design. Finally, the effectiveness and correctness of the process are verified by simulation of the actual optical system, pointing out that the <em>D</em><sub>1</sub>, <em>D</em><sub>2</sub>, <em>D</em><sub>3</sub>, and <em>R</em><sub>5</sub> terms need to be calibrated and optimized to ensure polarization accuracy. This method offers a valuable tool and theoretical guidance for the polarization design of high-precision optical systems.</div></div>","PeriodicalId":49719,"journal":{"name":"Optics and Lasers in Engineering","volume":"184 ","pages":"Article 108598"},"PeriodicalIF":3.5,"publicationDate":"2024-09-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142323010","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-09-25DOI: 10.1016/j.optlaseng.2024.108604
Sotero Ordones , Jorge L. Flores , Rong Su
In this paper, we introduce an iterative correcting algorithm for phase demodulation in optical metrology via phase-shifting interferometry. The scheme can effectively cope with interferograms with both temporal intensity variations and non-uniformly spaced phase shifts. When the background intensity and fringe visibility vary only over time while spatially remaining constants, our approach can iteratively estimate and correct them. For each iteration, we propose retrieving the phase shifts and the temporal variations, and then we extract the phase map from the corrected interferograms. We provide the spectral analysis of the method according to the frequency transfer function (FTF) formalism for phase-shifting algorithms. Results show that our scheme can accurately retrieve the phase map where the demodulation errors are unintelligible. Additionally, our method has computational time comparable to state-of-the-art iterative algorithms for non-uniformly phase-shifted interferograms, converging rapidly within ten iterations.
{"title":"Iteratively correcting algorithm for suppressing temporal variations in phase-shifting interferometry","authors":"Sotero Ordones , Jorge L. Flores , Rong Su","doi":"10.1016/j.optlaseng.2024.108604","DOIUrl":"10.1016/j.optlaseng.2024.108604","url":null,"abstract":"<div><div>In this paper, we introduce an iterative correcting algorithm for phase demodulation in optical metrology via phase-shifting interferometry. The scheme can effectively cope with interferograms with both temporal intensity variations and non-uniformly spaced phase shifts. When the background intensity and fringe visibility vary only over time while spatially remaining constants, our approach can iteratively estimate and correct them. For each iteration, we propose retrieving the phase shifts and the temporal variations, and then we extract the phase map from the corrected interferograms. We provide the spectral analysis of the method according to the frequency transfer function (FTF) formalism for phase-shifting algorithms. Results show that our scheme can accurately retrieve the phase map where the demodulation errors are unintelligible. Additionally, our method has computational time comparable to state-of-the-art iterative algorithms for non-uniformly phase-shifted interferograms, converging rapidly within ten iterations.</div></div>","PeriodicalId":49719,"journal":{"name":"Optics and Lasers in Engineering","volume":"184 ","pages":"Article 108604"},"PeriodicalIF":3.5,"publicationDate":"2024-09-25","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142319753","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-09-24DOI: 10.1016/j.optlaseng.2024.108607
Wenbo Wan , Xueqing Li , Jing Li , Meiling Xu , Haoran Lv , Jiande Sun
With the advancement of imaging technology, macrophotography images (MPIs) have become a popular research topic. Unlike natural images, MPIs often feature sharp foregrounds and blurred backgrounds, leading to distinct perceptual characteristics in estimation. As the number of MPIs grows rapidly, concerns over image quality and security increase. Robust watermarking techniques have been introduced to address these challenges. Just Noticeable Difference (JND) has been widely used in quantization-based watermarking frameworks. However, existing JND models handle each image area with a single-level perceptual attention. Visual attention in Quaternion Discrete Wavelet Transform (QDWT), which can reflect the Multi-level perceptual attention feature. Therefore, we propose a new method called Quaternion Attention-based Just Noticeable Difference model for MPIs Watemarking (QAJnd-MW) for watermarking MPIs. This method uses visual attention mechanisms, recognizing that the HVS is more sensitive to attention regions. We generate a masking effect in the JND field. The input image undergoes QDWT to explore multi-scale features. The multi-scale feature maps, with multi-directional luminance and multi-channel color, help create local and global attention maps, which are fused to form the final attention map. Specifically, considering both attention-based masking effects, the quaternion attention-guided JND model is designed for a robust MPI watermarking framework, aiming to further improve MPI security. Extensive experiments on the MP2020 and Blur Detection datasets show that the proposed model significantly improves robustness against JPEG compression attacks, reducing the bit error rate (BER) by up to 12%. Additionally, the model performs well against other attacks, such as those in online social networks, with lower BER than current state-of-the-art techniques.
{"title":"Quaternion attention-based JND model for macrophotography image watermarking","authors":"Wenbo Wan , Xueqing Li , Jing Li , Meiling Xu , Haoran Lv , Jiande Sun","doi":"10.1016/j.optlaseng.2024.108607","DOIUrl":"10.1016/j.optlaseng.2024.108607","url":null,"abstract":"<div><div>With the advancement of imaging technology, macrophotography images (MPIs) have become a popular research topic. Unlike natural images, MPIs often feature sharp foregrounds and blurred backgrounds, leading to distinct perceptual characteristics in estimation. As the number of MPIs grows rapidly, concerns over image quality and security increase. Robust watermarking techniques have been introduced to address these challenges. Just Noticeable Difference (JND) has been widely used in quantization-based watermarking frameworks. However, existing JND models handle each image area with a single-level perceptual attention. Visual attention in Quaternion Discrete Wavelet Transform (QDWT), which can reflect the Multi-level perceptual attention feature. Therefore, we propose a new method called <strong>Q</strong>uaternion <strong>A</strong>ttention-based <strong>J</strong>ust <strong>N</strong>oticeable <strong>D</strong>ifference model for <strong>M</strong>PIs <strong>W</strong>atemarking <strong>(QAJnd-MW)</strong> for watermarking MPIs. This method uses visual attention mechanisms, recognizing that the HVS is more sensitive to attention regions. We generate a masking effect in the JND field. The input image undergoes QDWT to explore multi-scale features. The multi-scale feature maps, with multi-directional luminance and multi-channel color, help create local and global attention maps, which are fused to form the final attention map. Specifically, considering both attention-based masking effects, the quaternion attention-guided JND model is designed for a robust MPI watermarking framework, aiming to further improve MPI security. Extensive experiments on the MP2020 and Blur Detection datasets show that the proposed model significantly improves robustness against JPEG compression attacks, reducing the bit error rate (BER) by up to 12%. Additionally, the model performs well against other attacks, such as those in online social networks, with lower BER than current state-of-the-art techniques.</div></div>","PeriodicalId":49719,"journal":{"name":"Optics and Lasers in Engineering","volume":"184 ","pages":"Article 108607"},"PeriodicalIF":3.5,"publicationDate":"2024-09-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142315117","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-09-23DOI: 10.1016/j.optlaseng.2024.108606
Mateusz Kaluza , Paweł Komorowski , Mateusz Surma , Adrianna Nieradka , Przemysław Zagrajek , Agnieszka Siemion
In recent years, there has been growing interest in the utilization of terahertz (THz) technologies in telecommunications applications. In such systems, radiation multiplexing is required. In one of the solutions, multiplexing can be achieved through the application of appropriate passive optical components. In this study, three different designs of passive diffractive optical elements (DOEs) that meet the functionality of spatial multiplexing of THz radiation are presented. The functionality was achieved by combining two spatially separated optical channels into a single optical path with an addition of the focusing effect, creating multiple-input single-output (MISO) system performance. Two structures were designed as various combinations of off-axis segmentation of kinoform focusing lenses with particular shifts. However, the distribution of the third structure was created with the interactive algorithm. The performance of all structures was verified with numerical simulations using propagation based on the modified convolution method, giving promising results. In this study, the novel, specially dedicated method of 3D modeling was applied. MISO structures were manufactured using fused deposition modeling (FDM) 3D printing technology from styrene-butadiene copolymer (SBC) material, which is remarkably transparent for the THz radiation range (its absorption coefficient value is less than 1 cm−1 in the range up to 750 GHz). The manufactured structures were examined in the experimental setup. All three MISO structures demonstrated proper functionality by redirecting and focusing radiation from two spatially separated radiation sources into the single focal spot located on the main optical axis. However, the structure designed with the iterative algorithm significantly surpassed the performance of the other structures. This structure redirected over two times higher intensity in the desired manner and exhibited approximately 68.12% higher relative efficiency compared to the others. The structure designed with an iterative method is recommended for further investigation and future application in 6G telecommunication systems.
{"title":"Advanced diffractive optical elements implementing multiple-input spatial multiplexing of terahertz radiation","authors":"Mateusz Kaluza , Paweł Komorowski , Mateusz Surma , Adrianna Nieradka , Przemysław Zagrajek , Agnieszka Siemion","doi":"10.1016/j.optlaseng.2024.108606","DOIUrl":"10.1016/j.optlaseng.2024.108606","url":null,"abstract":"<div><div>In recent years, there has been growing interest in the utilization of terahertz (THz) technologies in telecommunications applications. In such systems, radiation multiplexing is required. In one of the solutions, multiplexing can be achieved through the application of appropriate passive optical components. In this study, three different designs of passive diffractive optical elements (DOEs) that meet the functionality of spatial multiplexing of THz radiation are presented. The functionality was achieved by combining two spatially separated optical channels into a single optical path with an addition of the focusing effect, creating multiple-input single-output (MISO) system performance. Two structures were designed as various combinations of off-axis segmentation of kinoform focusing lenses with particular shifts. However, the distribution of the third structure was created with the interactive algorithm. The performance of all structures was verified with numerical simulations using propagation based on the modified convolution method, giving promising results. In this study, the novel, specially dedicated method of 3D modeling was applied. MISO structures were manufactured using fused deposition modeling (FDM) 3D printing technology from styrene-butadiene copolymer (SBC) material, which is remarkably transparent for the THz radiation range (its absorption coefficient value is less than 1 cm<sup>−1</sup> in the range up to 750 GHz). The manufactured structures were examined in the experimental setup. All three MISO structures demonstrated proper functionality by redirecting and focusing radiation from two spatially separated radiation sources into the single focal spot located on the main optical axis. However, the structure designed with the iterative algorithm significantly surpassed the performance of the other structures. This structure redirected over two times higher intensity in the desired manner and exhibited approximately 68.12% higher relative efficiency compared to the others. The structure designed with an iterative method is recommended for further investigation and future application in 6G telecommunication systems.</div></div>","PeriodicalId":49719,"journal":{"name":"Optics and Lasers in Engineering","volume":"184 ","pages":"Article 108606"},"PeriodicalIF":3.5,"publicationDate":"2024-09-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.sciencedirect.com/science/article/pii/S0143816624005840/pdfft?md5=b3d1ea29a4af3671b650a1689fe516c5&pid=1-s2.0-S0143816624005840-main.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142310702","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-09-23DOI: 10.1016/j.optlaseng.2024.108599
Ning Xu , Dalong Qi , Chengzhi Jin , Jiayi Mao , Yu He , Yunhua Yao , Yuecheng Shen , Lianzhong Deng , Zhiyong Wang , Zhenrong Sun , Shian Zhang
Snapshot temporal compressive imaging offers a potent method for capturing high-dimensional spatiotemporal information from a superimposed 2D image of a dynamic scene. However, despite its notable bandwidth-saving capability, simultaneous acquisition of spatiotemporal intensity and phase information remains challenging due to the phase insensitivity of detectors. To address this issue, a novel temporal compressive complex amplitude imaging (TCCAI) method based on double random phase encoding is proposed here. Within TCCAI, the target scene undergoes spatial modulation by a static phase mask in the spatial domain, followed by spatial encoding by an ultrahigh-speed-switchable phase mask in the spatial frequency domain after a Fourier transform. Adjacently, the scene is inversely Fourier transformed and integrally exposed onto a planar detector. Ultimately, the complex amplitude information, sensitive to both intensity and phase, can be faithfully reconstructed over time using a plug-and-play-based deep image prior algorithm. The feasibility, robustness, and superiority of TCCAI over intensity encoding-based methods are demonstrated through simulation. This approach is expected to pave the way for real-time multidimensional temporal imaging.
{"title":"Temporal compressive complex amplitude imaging based on double random phase encoding","authors":"Ning Xu , Dalong Qi , Chengzhi Jin , Jiayi Mao , Yu He , Yunhua Yao , Yuecheng Shen , Lianzhong Deng , Zhiyong Wang , Zhenrong Sun , Shian Zhang","doi":"10.1016/j.optlaseng.2024.108599","DOIUrl":"10.1016/j.optlaseng.2024.108599","url":null,"abstract":"<div><div>Snapshot temporal compressive imaging offers a potent method for capturing high-dimensional spatiotemporal information from a superimposed 2D image of a dynamic scene. However, despite its notable bandwidth-saving capability, simultaneous acquisition of spatiotemporal intensity and phase information remains challenging due to the phase insensitivity of detectors. To address this issue, a novel temporal compressive complex amplitude imaging (TC<img>CAI) method based on double random phase encoding is proposed here. Within TC<img>CAI, the target scene undergoes spatial modulation by a static phase mask in the spatial domain, followed by spatial encoding by an ultrahigh-speed-switchable phase mask in the spatial frequency domain after a Fourier transform. Adjacently, the scene is inversely Fourier transformed and integrally exposed onto a planar detector. Ultimately, the complex amplitude information, sensitive to both intensity and phase, can be faithfully reconstructed over time using a plug-and-play-based deep image prior algorithm. The feasibility, robustness, and superiority of TC<img>CAI over intensity encoding-based methods are demonstrated through simulation. This approach is expected to pave the way for real-time multidimensional temporal imaging.</div></div>","PeriodicalId":49719,"journal":{"name":"Optics and Lasers in Engineering","volume":"184 ","pages":"Article 108599"},"PeriodicalIF":3.5,"publicationDate":"2024-09-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142310700","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
We introduce an innovative approach for reducing speckle noise in holographic reconstruction images utilizing the Transformer architecture. This approach not only effectively captures speckle noise from digital holographic images but also better preserves details in images, owing to the characteristics of the Swin Transformer in globally and locally capturing relationships between image features. The network is trained using a large dataset with a distribution similar to real speckle noise. Experimental results demonstrate outstanding denoising performance of the proposed method and effectively preserving the details.
{"title":"Speckle noise reduction for digital holographic images using Swin Transformer","authors":"ZhaoQian Xie , Li Chen , HongHui Chen , KunHua Wen , JunWei Guo","doi":"10.1016/j.optlaseng.2024.108605","DOIUrl":"10.1016/j.optlaseng.2024.108605","url":null,"abstract":"<div><p>We introduce an innovative approach for reducing speckle noise in holographic reconstruction images utilizing the Transformer architecture. This approach not only effectively captures speckle noise from digital holographic images but also better preserves details in images, owing to the characteristics of the Swin Transformer in globally and locally capturing relationships between image features. The network is trained using a large dataset with a distribution similar to real speckle noise. Experimental results demonstrate outstanding denoising performance of the proposed method and effectively preserving the details.</p></div>","PeriodicalId":49719,"journal":{"name":"Optics and Lasers in Engineering","volume":"184 ","pages":"Article 108605"},"PeriodicalIF":3.5,"publicationDate":"2024-09-21","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142271740","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-09-21DOI: 10.1016/j.optlaseng.2024.108608
Fujia Liu , Zhekai Li , Jianhong Yang , Jin Guo , Meiling Wang , Hongsen Wang
Laser speckle based digital image correlation is a promising method for measuring the full-field deformation at elevated temperatures because of its no need of preparation of high-temperature-resistant speckle pattern. However, uneven exposure problems often arise in cases of non-uniformly distributed temperatures, or uneven luminance caused by curved surface of specimens especially when a laser source is used. Techniques like adjusting the exposure time or aperture size are ineffective if the dynamic range of image capturing devices is smaller than the luminance gradient of the analysis area of specimens. Traditional high dynamic range imaging fusion methods confront challenges in deformation measurement because the subject during the deformation is changing and motion blur may occur in the images. Therefore, an adaptive high dynamic range(HDR) imaging fusion method is proposed to cope with uneven-exposure problems in full-field deformation measurement using laser speckle digital image correlation. The proposed method includes an adaptive selection criterion for exposure parameters of laser speckle images, which can be used to prevent motion blur within the exposure time range. And high dynamic range imaging fusion method is then applied to achieve a synthesized image with high quality which can be used for digital image correlation. Experiments on deformation measurement in tensile tests of cylindrical specimens at 1300 °C using Gleeble 3500 testing device was carried out. The proposed method successfully addressed the uneven exposure problem and provided full-field deformation map with more accurate and comprehensive results.
基于激光斑点的数字图像相关技术无需制备耐高温斑点图案，因此是测量高温下全场变形的理想方法。然而，在温度分布不均匀或试样表面弯曲导致亮度不均匀的情况下，尤其是使用激光源时，经常会出现曝光不均匀的问题。如果图像捕捉设备的动态范围小于试样分析区域的亮度梯度，调整曝光时间或光圈大小等技术就会失效。传统的高动态范围成像融合方法在形变测量中面临挑战，因为在形变过程中被测物是不断变化的，图像中可能会出现运动模糊。因此，本文提出了一种自适应高动态范围（HDR）成像融合方法，利用激光斑点数字图像相关技术解决全场形变测量中的曝光不均问题。该方法包括激光斑点图像曝光参数的自适应选择准则，可用于防止曝光时间范围内的运动模糊。然后应用高动态范围成像融合方法，获得可用于数字图像相关性的高质量合成图像。使用 Gleeble 3500 测试设备对 1300 °C 下的圆柱形试样拉伸试验进行了变形测量实验。所提出的方法成功地解决了曝光不均匀的问题，并提供了更准确、更全面的全场变形图。
{"title":"An adaptive high dynamic range imaging fusion method to overcome high luminance gradient in full-field deformation measurement using laser speckle digital image correlation","authors":"Fujia Liu , Zhekai Li , Jianhong Yang , Jin Guo , Meiling Wang , Hongsen Wang","doi":"10.1016/j.optlaseng.2024.108608","DOIUrl":"10.1016/j.optlaseng.2024.108608","url":null,"abstract":"<div><div>Laser speckle based digital image correlation is a promising method for measuring the full-field deformation at elevated temperatures because of its no need of preparation of high-temperature-resistant speckle pattern. However, uneven exposure problems often arise in cases of non-uniformly distributed temperatures, or uneven luminance caused by curved surface of specimens especially when a laser source is used. Techniques like adjusting the exposure time or aperture size are ineffective if the dynamic range of image capturing devices is smaller than the luminance gradient of the analysis area of specimens. Traditional high dynamic range imaging fusion methods confront challenges in deformation measurement because the subject during the deformation is changing and motion blur may occur in the images. Therefore, an adaptive high dynamic range(HDR) imaging fusion method is proposed to cope with uneven-exposure problems in full-field deformation measurement using laser speckle digital image correlation. The proposed method includes an adaptive selection criterion for exposure parameters of laser speckle images, which can be used to prevent motion blur within the exposure time range. And high dynamic range imaging fusion method is then applied to achieve a synthesized image with high quality which can be used for digital image correlation. Experiments on deformation measurement in tensile tests of cylindrical specimens at 1300 °C using Gleeble 3500 testing device was carried out. The proposed method successfully addressed the uneven exposure problem and provided full-field deformation map with more accurate and comprehensive results.</div></div>","PeriodicalId":49719,"journal":{"name":"Optics and Lasers in Engineering","volume":"184 ","pages":"Article 108608"},"PeriodicalIF":3.5,"publicationDate":"2024-09-21","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142310699","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-09-20DOI: 10.1016/j.optlaseng.2024.108601
Lixia Li , Lin Cui , Xueyang Zong , Yuhang Huang , Yuzhang Liang , Ning Feng , Yufang Liu
A large-scale and low-cost plasmonic nanodisk/hole array on flexible substrate for advanced biochemical sensing detection application is demonstrated by using the combined fabrication method of vacuum coating and nanoimprinting. Two distinct resonance dips from the proposed quasi-3D nanodisk/hole array are observed and analyzed at the nonzero incidence angle, exhibiting excellent sensing performance with both the bulk and surface sensitivity. Furthermore, the highly localized electromagnetic field within the nanodisk/hole array enables it to detect bovine serum albumin biomolecule at an ultra-low concentration of 100 nM, and Hg2+ specific detection with the detection limit as small as 0.26 μM. This large-scale and cheap sensing chip possesses broad applications prospects in the development of medical point-of-care diagnostics and drug discovery research.
{"title":"A quasi-3D large-scale plasmonic nanodisk-hole array on flexible substrate for detection application","authors":"Lixia Li , Lin Cui , Xueyang Zong , Yuhang Huang , Yuzhang Liang , Ning Feng , Yufang Liu","doi":"10.1016/j.optlaseng.2024.108601","DOIUrl":"10.1016/j.optlaseng.2024.108601","url":null,"abstract":"<div><p>A large-scale and low-cost plasmonic nanodisk/hole array on flexible substrate for advanced biochemical sensing detection application is demonstrated by using the combined fabrication method of vacuum coating and nanoimprinting. Two distinct resonance dips from the proposed quasi-3D nanodisk/hole array are observed and analyzed at the nonzero incidence angle, exhibiting excellent sensing performance with both the bulk and surface sensitivity. Furthermore, the highly localized electromagnetic field within the nanodisk/hole array enables it to detect bovine serum albumin biomolecule at an ultra-low concentration of 100 nM, and Hg<sup>2+</sup> specific detection with the detection limit as small as 0.26 μM. This large-scale and cheap sensing chip possesses broad applications prospects in the development of medical point-of-care diagnostics and drug discovery research.</p></div>","PeriodicalId":49719,"journal":{"name":"Optics and Lasers in Engineering","volume":"184 ","pages":"Article 108601"},"PeriodicalIF":3.5,"publicationDate":"2024-09-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142269008","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
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