Pub Date : 2024-11-16DOI: 10.1016/j.optlaseng.2024.108694
J. Lobera , A.M. López Torres , N. Andrés , F.J. Torcal-Milla , E.M. Roche , V. Palero
The application of digital in-line holography in fluid velocimetry is mainly limited by the twin image that hinders the particle position and velocity measurements. In this work, we propose the use of two spiral phase filters in a digital in-line holography configuration to discriminate the real and virtual images. The first filter is a physical plate that modifies the object spectrum prior the recording. The second filter is a numerical frequency filter, applied in the reconstruction process, which reshape one of the particle images into a point-like image while blurs its twin image. In this way, particle tracking algorithms, based on the detection of intensity peaks, can easily locate and track particles. The good performance of double spiral phase filter in-line holography for particle field recording and particle tracking has been demonstrated experimentally in the present work.
{"title":"Double spiral phase filter digital in-line holography for particle field recording and tracking","authors":"J. Lobera , A.M. López Torres , N. Andrés , F.J. Torcal-Milla , E.M. Roche , V. Palero","doi":"10.1016/j.optlaseng.2024.108694","DOIUrl":"10.1016/j.optlaseng.2024.108694","url":null,"abstract":"<div><div>The application of digital in-line holography in fluid velocimetry is mainly limited by the twin image that hinders the particle position and velocity measurements. In this work, we propose the use of two spiral phase filters in a digital in-line holography configuration to discriminate the real and virtual images. The first filter is a physical plate that modifies the object spectrum prior the recording. The second filter is a numerical frequency filter, applied in the reconstruction process, which reshape one of the particle images into a point-like image while blurs its twin image. In this way, particle tracking algorithms, based on the detection of intensity peaks, can easily locate and track particles. The good performance of double spiral phase filter in-line holography for particle field recording and particle tracking has been demonstrated experimentally in the present work.</div></div>","PeriodicalId":49719,"journal":{"name":"Optics and Lasers in Engineering","volume":"184 ","pages":"Article 108694"},"PeriodicalIF":3.5,"publicationDate":"2024-11-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142661120","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 : 2024-11-16DOI: 10.1016/j.optlaseng.2024.108693
Xiangyu Wang , Lei Zhu , Qi Zhang , Liang Yang , Min Tang , Fei Xiao , Xiaodong Wang , Shiyang Shen , Lanqiang Zhang , Youming Guo
Optical aberrations are critical for high-precision and large-depth fabrication of femtosecond lasers in transparent media. Some approaches have been demonstrated to correct these aberrations, such as calculated formulas, iterative algorithms for phase retrieval, and neural networks. However, these approaches have a few drawbacks, such as insufficient aberration correction and a lack of real-time operation, limiting the processing depth and performance of the device. Thus, this study demonstrated an aberration correction scheme with direct wavefront sensing. The aberrations during processing at different depths, from 100 to 600 μm, were measured using a Shack-Hartmann wavefront sensor. As a guide star, this sensor used the supercontinuum emitted by the plasma, which is generated by multiphoton absorption and avalanche effects in the focal region. A liquid-crystal spatial light modulator (SLM) effectively compensated the aberrations. Voxels with a constant aspect ratio of 2.82–2.91 were fabricated in different depths, significantly lower than the aspect ratio of 4.46–19.5 with uncorrected aberrations. This technology allows the precise fabrication of three-dimensional photonic devices consisting of curved waveguides at continuously different depths and improves the throughput of laser processing.
{"title":"Femtosecond laser processing with aberration correction based on Shack-Hartmann wavefront sensor","authors":"Xiangyu Wang , Lei Zhu , Qi Zhang , Liang Yang , Min Tang , Fei Xiao , Xiaodong Wang , Shiyang Shen , Lanqiang Zhang , Youming Guo","doi":"10.1016/j.optlaseng.2024.108693","DOIUrl":"10.1016/j.optlaseng.2024.108693","url":null,"abstract":"<div><div>Optical aberrations are critical for high-precision and large-depth fabrication of femtosecond lasers in transparent media. Some approaches have been demonstrated to correct these aberrations, such as calculated formulas, iterative algorithms for phase retrieval, and neural networks. However, these approaches have a few drawbacks, such as insufficient aberration correction and a lack of real-time operation, limiting the processing depth and performance of the device. Thus, this study demonstrated an aberration correction scheme with direct wavefront sensing. The aberrations during processing at different depths, from 100 to 600 μm, were measured using a Shack-Hartmann wavefront sensor. As a guide star, this sensor used the supercontinuum emitted by the plasma, which is generated by multiphoton absorption and avalanche effects in the focal region. A liquid-crystal spatial light modulator (SLM) effectively compensated the aberrations. Voxels with a constant aspect ratio of 2.82–2.91 were fabricated in different depths, significantly lower than the aspect ratio of 4.46–19.5 with uncorrected aberrations. This technology allows the precise fabrication of three-dimensional photonic devices consisting of curved waveguides at continuously different depths and improves the throughput of laser processing.</div></div>","PeriodicalId":49719,"journal":{"name":"Optics and Lasers in Engineering","volume":"184 ","pages":"Article 108693"},"PeriodicalIF":3.5,"publicationDate":"2024-11-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142661121","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 : 2024-11-16DOI: 10.1016/j.optlaseng.2024.108691
Rui Xia, Haodong Zhu, Ruiqi Yin, Ming Zhao, Zhenyu Yang
In many optical applications, vortex beam is widely used in optical communications, quantum information processing and other fields due to its unique properties. And in the field of imaging, it is crucial to obtain high quality and clear images. Current strategies mainly observe the interference fringes of the vortex beam and the Gaussian beam or use external optics to measure the topological charges (TCs), and apply machine learning in the back-end processing to denoise the image. The emerging diffractive deep neural network (D2NN) proposes a novel solution. Here, we introduce a multifunctional processor based on cascaded switchable polarization-multiplexed metasurface. It realizes the TC measurement and image denoising by exploiting the polarization-sensitive properties of anisotropic meta-atoms, which generate different phase responses under varying polarization states of incident light. Different types of noisy images, noise models, and noise ratios can be denoised by switching the metasurface. This study highlights the potential applications of integrating metasurfaces with D2NN through numerical simulation validation, expanding possibilities by transforming metasurfaces into multifunctional processors.
{"title":"Multifunctional processor based on cascaded switchable polarization-multiplexed metasurface","authors":"Rui Xia, Haodong Zhu, Ruiqi Yin, Ming Zhao, Zhenyu Yang","doi":"10.1016/j.optlaseng.2024.108691","DOIUrl":"10.1016/j.optlaseng.2024.108691","url":null,"abstract":"<div><div>In many optical applications, vortex beam is widely used in optical communications, quantum information processing and other fields due to its unique properties. And in the field of imaging, it is crucial to obtain high quality and clear images. Current strategies mainly observe the interference fringes of the vortex beam and the Gaussian beam or use external optics to measure the topological charges (TCs), and apply machine learning in the back-end processing to denoise the image. The emerging diffractive deep neural network (D<sup>2</sup>NN) proposes a novel solution. Here, we introduce a multifunctional processor based on cascaded switchable polarization-multiplexed metasurface. It realizes the TC measurement and image denoising by exploiting the polarization-sensitive properties of anisotropic meta-atoms, which generate different phase responses under varying polarization states of incident light. Different types of noisy images, noise models, and noise ratios can be denoised by switching the metasurface. This study highlights the potential applications of integrating metasurfaces with D<sup>2</sup>NN through numerical simulation validation, expanding possibilities by transforming metasurfaces into multifunctional processors.</div></div>","PeriodicalId":49719,"journal":{"name":"Optics and Lasers in Engineering","volume":"184 ","pages":"Article 108691"},"PeriodicalIF":3.5,"publicationDate":"2024-11-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142661119","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 : 2024-11-15DOI: 10.1016/j.optlaseng.2024.108678
Juan Martinez-Carranza , Jose Martinez-Carranza , Tomasz Kozacki
Holographic Near Eye Displays (HNEDs) are meant to be the next generation of electronic devices that enable projecting three-dimensional images directly to the eyes. This is possible because computer-generated holograms (CGHs), the backbone of HNEDs, encode accurate wavefront information from virtual objects. An immersive experience requires that these CGHs can reproduce large and highly detailed objects. Moreover, an occlusion culling algorithm is necessary to remove back surfaces that do not contribute to the scene, which provides a better sense of reality. Although there is a vast family of occlusion culling methods, none of these, to the best of our knowledge, consider occlusion when calculating CGHs for field of views (FoV) larger than 90° This work proposes a point cloud occlusion culling method for CGHs that projects images with angles larger than 90° Our approach is based on the geometry of the non-pupil Near Eye Display configuration. It is shown that this configuration provides the proper geometrical conditions that can be used for setting fast occlusion culling of unwanted back points. Occlusion culling with our method is carried out with clouds larger than 7-million-point sources and CGHs resolution of 4 K and 8K. It is demonstrated that our method is at least 5 times faster than current solutions. Furthermore, occluded clouds are used for calculating CGHs that are numerically and optically reconstructed. The obtained results confirm that our method provides high-quality occluded clouds, enabling high-quality production of CGHs with large FoV.
{"title":"Efficient point cloud occlusion method for ultra wide-angle computer-generated holograms","authors":"Juan Martinez-Carranza , Jose Martinez-Carranza , Tomasz Kozacki","doi":"10.1016/j.optlaseng.2024.108678","DOIUrl":"10.1016/j.optlaseng.2024.108678","url":null,"abstract":"<div><div>Holographic Near Eye Displays (HNEDs) are meant to be the next generation of electronic devices that enable projecting three-dimensional images directly to the eyes. This is possible because computer-generated holograms (CGHs), the backbone of HNEDs, encode accurate wavefront information from virtual objects. An immersive experience requires that these CGHs can reproduce large and highly detailed objects. Moreover, an occlusion culling algorithm is necessary to remove back surfaces that do not contribute to the scene, which provides a better sense of reality. Although there is a vast family of occlusion culling methods, none of these, to the best of our knowledge, consider occlusion when calculating CGHs for field of views (FoV) larger than 90° This work proposes a point cloud occlusion culling method for CGHs that projects images with angles larger than 90° Our approach is based on the geometry of the non-pupil Near Eye Display configuration. It is shown that this configuration provides the proper geometrical conditions that can be used for setting fast occlusion culling of unwanted back points. Occlusion culling with our method is carried out with clouds larger than 7-million-point sources and CGHs resolution of 4 K and 8K. It is demonstrated that our method is at least 5 times faster than current solutions. Furthermore, occluded clouds are used for calculating CGHs that are numerically and optically reconstructed. The obtained results confirm that our method provides high-quality occluded clouds, enabling high-quality production of CGHs with large FoV.</div></div>","PeriodicalId":49719,"journal":{"name":"Optics and Lasers in Engineering","volume":"184 ","pages":"Article 108678"},"PeriodicalIF":3.5,"publicationDate":"2024-11-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142661118","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 : 2024-11-15DOI: 10.1016/j.optlaseng.2024.108692
Jack B.P. Atkinson, Jonathan R. Howse
This work presents a novel optical setup to provide scalable in-situ metrology during spin coating. Stroboscopic white light imaging provides high resolution color videos of the process, at a temporal resolution matching the spin speed, where thin film interference colors are observed. Monochromatic specular reflection intensity data from the center of rotation provides a thickness profile at this point. By developing a color to thickness relationship in-situ with the combination of these techniques and leveraging the large-area data provided by color imaging, the thickness at any point on the wafer is reconstructed via a mapping procedure with minimal a-priori information. Experiments are carried out on full 3″ diameter wafers spun with pure xylene or pure butyl acetate, and the thickness profile at all points on the wafer can be determined. Differences in the topology of these solvents whilst drying are linked back to the solvent properties. The color to thickness mapping procedure is shown to have less than 5 % error in determined thickness values between 2μm and 100nm. The possible length scale resolved by the imaging is fully discussed as a function of radius, spin speed, strobe pulse duration and hardware used. The studies in this work achieved a minimum lateral resolution of 315μm when observing a full wafer, which is sufficiently detailed to properly reconstruct thickness variations caused by common spin-coating defects such as comets. The large area and scalable nature of this metrology technique lends itself to applications in semiconductor manufacturing where substrates of 300 mm are standard.
{"title":"In-situ full-wafer metrology via coupled white light and monochromatic stroboscopic illumination","authors":"Jack B.P. Atkinson, Jonathan R. Howse","doi":"10.1016/j.optlaseng.2024.108692","DOIUrl":"10.1016/j.optlaseng.2024.108692","url":null,"abstract":"<div><div>This work presents a novel optical setup to provide scalable <em>in-situ</em> metrology during spin coating. Stroboscopic white light imaging provides high resolution color videos of the process, at a temporal resolution matching the spin speed, where thin film interference colors are observed. Monochromatic specular reflection intensity data from the center of rotation provides a thickness profile at this point. By developing a color to thickness relationship <em>in-situ</em> with the combination of these techniques and leveraging the large-area data provided by color imaging, the thickness at any point on the wafer is reconstructed via a mapping procedure with minimal a-priori information. Experiments are carried out on full 3″ diameter wafers spun with pure xylene or pure butyl acetate, and the thickness profile at all points on the wafer can be determined. Differences in the topology of these solvents whilst drying are linked back to the solvent properties. The color to thickness mapping procedure is shown to have less than 5 % error in determined thickness values between 2μm and 100nm. The possible length scale resolved by the imaging is fully discussed as a function of radius, spin speed, strobe pulse duration and hardware used. The studies in this work achieved a minimum lateral resolution of 315μm when observing a full wafer, which is sufficiently detailed to properly reconstruct thickness variations caused by common spin-coating defects such as comets. The large area and scalable nature of this metrology technique lends itself to applications in semiconductor manufacturing where substrates of 300 mm are standard.</div></div>","PeriodicalId":49719,"journal":{"name":"Optics and Lasers in Engineering","volume":"184 ","pages":"Article 108692"},"PeriodicalIF":3.5,"publicationDate":"2024-11-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142661195","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}
Aiming at the difficult to detect arbitrary-angle weld defects, a magneto-optical (MO) imaging non-destructive testing (NDT) system for weld defects excited by different magnetic fields is studied. The mechanism of the alternating magnetic field generated by the U-shaped yoke and the rotating magnetic field produced by the plane cross yoke is introduced, the magnetic field distribution of weld defects is analyzed by using finite element simulation. The MO imaging effects of different weld defects excited by alternating/rotating magnetic field are compared. The relationship between imaging characteristics of MO images and magnetic field strength is analyzed based on the Faraday rotation effect. The gray value of MO image can match the corresponding leakage magnetic field strength. MO imaging NDT experiments are performed on weld defects, including non-penetration, pit, surface crack, and subsurface crack. The principal component analysis (PCA) method is used to extract the grayscale features of the fused image column pixels and the texture features of the MO image are extracted by the gray-level co-occurrence matrix (GLCM). A BP-AdaBoost neural network model and a support vector machine (SVM) model are established to identify these defect features. Experimental results show that the classification accuracy of the BP-AdaBoost neural network model and the SVM model can reach 98.2 % and 98.6 % respectively under the excitation of rotating magnetic field. Compared with the alternating magnetic field, the classification accuracy is improved by 7.5 % and 8.5 %, respectively. MO imaging under rotating magnetic field excitation overcomes the limitation of directional detection of MO imaging under traditional magnetic field excitation, and realizes the detection and classification of arbitrary-angle weld defects.
针对难以检测任意角度焊接缺陷的问题，研究了一种针对不同磁场激发的焊接缺陷的磁光（MO）成像无损检测（NDT）系统。介绍了 U 形磁轭产生的交变磁场和平面十字磁轭产生的旋转磁场的机理，并使用有限元模拟分析了焊接缺陷的磁场分布。比较了交变/旋转磁场激发的不同焊接缺陷的 MO 成像效果。基于法拉第旋转效应，分析了 MO 图像的成像特征与磁场强度之间的关系。MO 图像的灰度值可与相应的泄漏磁场强度相匹配。对焊接缺陷进行了 MO 成像无损检测实验，包括非穿透、凹坑、表面裂纹和地下裂纹。采用主成分分析（PCA）方法提取融合图像列像素的灰度特征，并通过灰度级共现矩阵（GLCM）提取 MO 图像的纹理特征。建立 BP-AdaBoost 神经网络模型和支持向量机 (SVM) 模型来识别这些缺陷特征。实验结果表明，在旋转磁场的激励下，BP-AdaBoost 神经网络模型和 SVM 模型的分类准确率分别可达 98.2% 和 98.6%。与交变磁场相比，分类准确率分别提高了 7.5 % 和 8.5 %。旋转磁场激励下的 MO 成像克服了传统磁场激励下 MO 成像定向检测的局限性，实现了任意角度焊接缺陷的检测和分类。
{"title":"Magneto-optical imaging detection and classification of weld defects under alternating/rotating magnetic field excitation","authors":"Yanfeng Li , Xiangdong Gao , Qun Gao , Jian Liu , Yanxi Zhang , Yiwei Zhu , Wei Wu , Wei Xu","doi":"10.1016/j.optlaseng.2024.108679","DOIUrl":"10.1016/j.optlaseng.2024.108679","url":null,"abstract":"<div><div>Aiming at the difficult to detect arbitrary-angle weld defects, a magneto-optical (MO) imaging non-destructive testing (NDT) system for weld defects excited by different magnetic fields is studied. The mechanism of the alternating magnetic field generated by the U-shaped yoke and the rotating magnetic field produced by the plane cross yoke is introduced, the magnetic field distribution of weld defects is analyzed by using finite element simulation. The MO imaging effects of different weld defects excited by alternating/rotating magnetic field are compared. The relationship between imaging characteristics of MO images and magnetic field strength is analyzed based on the Faraday rotation effect. The gray value of MO image can match the corresponding leakage magnetic field strength. MO imaging NDT experiments are performed on weld defects, including non-penetration, pit, surface crack, and subsurface crack. The principal component analysis (PCA) method is used to extract the grayscale features of the fused image column pixels and the texture features of the MO image are extracted by the gray-level co-occurrence matrix (GLCM). A BP-AdaBoost neural network model and a support vector machine (SVM) model are established to identify these defect features. Experimental results show that the classification accuracy of the BP-AdaBoost neural network model and the SVM model can reach 98.2 % and 98.6 % respectively under the excitation of rotating magnetic field. Compared with the alternating magnetic field, the classification accuracy is improved by 7.5 % and 8.5 %, respectively. MO imaging under rotating magnetic field excitation overcomes the limitation of directional detection of MO imaging under traditional magnetic field excitation, and realizes the detection and classification of arbitrary-angle weld defects.</div></div>","PeriodicalId":49719,"journal":{"name":"Optics and Lasers in Engineering","volume":"184 ","pages":"Article 108679"},"PeriodicalIF":3.5,"publicationDate":"2024-11-14","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142661194","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 : 2024-11-14DOI: 10.1016/j.optlaseng.2024.108689
L.D. Hernández-Guerrero, J. Castillo-Mixcóatl, S. Muñoz-Aguirre, M. Rodríguez-Torres, E. Ramírez-Sánchez, G. Beltrán-Pérez
The techniques of multivariate analysis methods as prediction models open a new vision to the analysis of applied data. The method used in this work was projection to latent structures regression, which is a regression method that uses the latent variables generated by calculating the linear relationship between the dependent and independent variables giving them equal importance and thus obtaining the maximum variance and correlation of these variables. This method was applied to optical fiber sensors for acetone detection. It is important to detect acetone because it is a biomarker of diabetes mellitus. The sensor was fabricated with two cascaded long-period fiber gratings (LPFG) with a 515 µm grating period and separated 1 cm to form a Mach–Zehnder interferometer (MZI). Clinical studies for the diagnosis of diabetes are usually invasive, the development of these sensors proposes a new non-invasive option through the detection of acetone in human breath whose concentrations are in the order of 1.25–2.5 ppm. To study the response of the sensors to acetone, different sensing films, such as polydimethylsiloxane (PDMS), polymethyl methacrylate, Apiezon L and Apiezon T were used, which have a good affinity to this compound. Spectral changes in the transmission spectrum of the MZI were obtained due to the modes interference together with an increment of the sensitivity, since the interaction between the acetone concentration and the sensing film provokes a change in the effective index of the cladding, which in turn is amplified by the LPFGs separation. The analysis showed that the best results were obtained for the sensor with PDMS as sensing film, with the lowest limit of detection, 1.7 ppm using 4 latent structures.
{"title":"Projection to latent structures regression and its application to Mach–Zehnder interferometer optical fiber sensors for acetone detection","authors":"L.D. Hernández-Guerrero, J. Castillo-Mixcóatl, S. Muñoz-Aguirre, M. Rodríguez-Torres, E. Ramírez-Sánchez, G. Beltrán-Pérez","doi":"10.1016/j.optlaseng.2024.108689","DOIUrl":"10.1016/j.optlaseng.2024.108689","url":null,"abstract":"<div><div>The techniques of multivariate analysis methods as prediction models open a new vision to the analysis of applied data. The method used in this work was projection to latent structures regression, which is a regression method that uses the latent variables generated by calculating the linear relationship between the dependent and independent variables giving them equal importance and thus obtaining the maximum variance and correlation of these variables. This method was applied to optical fiber sensors for acetone detection. It is important to detect acetone because it is a biomarker of diabetes mellitus. The sensor was fabricated with two cascaded long-period fiber gratings (LPFG) with a 515 µm grating period and separated 1 cm to form a Mach–Zehnder interferometer (MZI). Clinical studies for the diagnosis of diabetes are usually invasive, the development of these sensors proposes a new non-invasive option through the detection of acetone in human breath whose concentrations are in the order of 1.25–2.5 ppm. To study the response of the sensors to acetone, different sensing films, such as polydimethylsiloxane (PDMS), polymethyl methacrylate, Apiezon L and Apiezon T were used, which have a good affinity to this compound. Spectral changes in the transmission spectrum of the MZI were obtained due to the modes interference together with an increment of the sensitivity, since the interaction between the acetone concentration and the sensing film provokes a change in the effective index of the cladding, which in turn is amplified by the LPFGs separation. The analysis showed that the best results were obtained for the sensor with PDMS as sensing film, with the lowest limit of detection, 1.7 ppm using 4 latent structures.</div></div>","PeriodicalId":49719,"journal":{"name":"Optics and Lasers in Engineering","volume":"184 ","pages":"Article 108689"},"PeriodicalIF":3.5,"publicationDate":"2024-11-14","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142661117","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 : 2024-11-09DOI: 10.1016/j.optlaseng.2024.108686
Longfei Zhang, Haoyuan Tan, Haozhong Lin, Pengcheng Lv, Lin Lin, Jun Zhou
Superior Al/Cu dissimilar metal joints is crucial for the development of the new energy electric vehicle industry. This study aims to enhance the mechanical properties of Al/Cu joints while minimizing their electrical contact resistance. Laser lap welding of 5A06 Al and T2 Cu was conducted applying an Alternating magnetic field (AMF) assisted method at various frequencies. Surface fluctuations, joint strength, and electrical contact resistance were compared with those of joints welded without the application of magnetic fields. The application of an AMF reduced the surface fluctuation of Al/Cu joints by 34.67 %, significantly improving the surface quality of the joints. Microscopic analysis of the welded joints reveals that, under the influence of the AMF, the α-Al and Al-Cu eutectic phase transform to Al2Cu and a mixture of α-Al and Al-Cu eutectic phase in the middle of the molten pool. Simultaneously, the Cu-rich Al4Cu9 phase is no longer observed at the bottom of the molten pool. Additionally, Al-Cu intermetallic compounds (IMCs), particularly Al2Cu, which accumulate at the junction of the bottom of the molten pool, are effectively dispersed under the action of the AMF. The growth of small Al2Cu is inhibited by the alternating Lorentz force, leading to simultaneous enhancements in both the mechanical properties and electrical conductivity of the Al/Cu joint. Tensile properties and electrical contact resistance measurements show that the shear resistance of the Al/Cu joints is improved by up to 19.03 %, and the electrical contact resistance is reduced by 1.2 % under the AMF-assisted condition at 150 Hz. In this study, AMF-assisted laser welding of Al/Cu significantly enhances the mechanical properties of the joints while reducing their electrical contact resistance. These findings provide valuable reference for producing superior Al/Cu joints for batteries in new energy electric vehicles.
{"title":"Research on the Al/Cu dissimilar metals laser welding process with alternating magnetic field assisted","authors":"Longfei Zhang, Haoyuan Tan, Haozhong Lin, Pengcheng Lv, Lin Lin, Jun Zhou","doi":"10.1016/j.optlaseng.2024.108686","DOIUrl":"10.1016/j.optlaseng.2024.108686","url":null,"abstract":"<div><div>Superior Al/Cu dissimilar metal joints is crucial for the development of the new energy electric vehicle industry. This study aims to enhance the mechanical properties of Al/Cu joints while minimizing their electrical contact resistance. Laser lap welding of 5A06 Al and T2 Cu was conducted applying an Alternating magnetic field (AMF) assisted method at various frequencies. Surface fluctuations, joint strength, and electrical contact resistance were compared with those of joints welded without the application of magnetic fields. The application of an AMF reduced the surface fluctuation of Al/Cu joints by 34.67 %, significantly improving the surface quality of the joints. Microscopic analysis of the welded joints reveals that, under the influence of the AMF, the α-Al and Al-Cu eutectic phase transform to Al<sub>2</sub>Cu and a mixture of α-Al and Al-Cu eutectic phase in the middle of the molten pool. Simultaneously, the Cu-rich Al<sub>4</sub>Cu<sub>9</sub> phase is no longer observed at the bottom of the molten pool. Additionally, Al-Cu intermetallic compounds (IMCs), particularly Al<sub>2</sub>Cu, which accumulate at the junction of the bottom of the molten pool, are effectively dispersed under the action of the AMF. The growth of small Al<sub>2</sub>Cu is inhibited by the alternating Lorentz force, leading to simultaneous enhancements in both the mechanical properties and electrical conductivity of the Al/Cu joint. Tensile properties and electrical contact resistance measurements show that the shear resistance of the Al/Cu joints is improved by up to 19.03 %, and the electrical contact resistance is reduced by 1.2 % under the AMF-assisted condition at 150 Hz. In this study, AMF-assisted laser welding of Al/Cu significantly enhances the mechanical properties of the joints while reducing their electrical contact resistance. These findings provide valuable reference for producing superior Al/Cu joints for batteries in new energy electric vehicles.</div></div>","PeriodicalId":49719,"journal":{"name":"Optics and Lasers in Engineering","volume":"184 ","pages":"Article 108686"},"PeriodicalIF":3.5,"publicationDate":"2024-11-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142661502","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 : 2024-11-09DOI: 10.1016/j.optlaseng.2024.108675
Na Yao , Jiao Jiao , Jingxuan Duan , Mo Chen , Duanpeng He
The super-oscillation (SO) phenomena successfully applied to super-resolution optical telescopes have yet to study the existence of atmospheric turbulence (AT). In this paper, we first experimentally investigate the sub-diffraction focusing of the SO light field in the atmospheric-like turbulence. The 137-element adaptive optics (AO) system is utilized to correct the dynamic wavefront aberration produced by the AT and obtain the AO closed-loop RMS of the residual wavefront error ∼λ/15. For a proofed telescope (clear aperture 12 mm and focal length 1000 mm) @λ=632.8 nm, the FWHM of the experimental SO spot under the modest AT (wavefront error RMS ∼0.57λ) is about 0.79 times of the Airy spot compared with the non-AT result of 0.76 times, while the strong AT (wavefront error RMS ∼1.35λ) erases the sub-diffraction focusing effect of the SO field and the average side-lobe intensity increases significantly. This study is promising for super-resolving telescope, synthetic aperture for visible imaging, etc.
成功应用于超分辨率光学望远镜的超振荡（SO）现象尚未研究大气湍流（AT）的存在。在本文中，我们首先通过实验研究了类大气湍流中 SO 光场的次衍射聚焦。利用 137 元自适应光学（AO）系统校正 AT 产生的动态波前像差，并获得 AO 闭环残余波前误差 RMS ∼λ/15。对于经过校准的望远镜（透明孔径 12 mm，焦距 1000 mm）@λ=632.8 nm，在适度 AT（波前误差均方根∼0.57λ）下，实验 SO 光斑的 FWHM 约为 Airy 光斑的 0.79 倍，而非 AT 的结果为 0.76 倍；而在强 AT（波前误差均方根∼1.35λ）下，SO 场的次衍射聚焦效应被消除，平均侧叶强度显著增加。这项研究有望用于超分辨望远镜、可见光成像合成孔径等。
{"title":"Super-oscillation sub-diffraction focusing with emulated atmospheric turbulence","authors":"Na Yao , Jiao Jiao , Jingxuan Duan , Mo Chen , Duanpeng He","doi":"10.1016/j.optlaseng.2024.108675","DOIUrl":"10.1016/j.optlaseng.2024.108675","url":null,"abstract":"<div><div>The super-oscillation (SO) phenomena successfully applied to super-resolution optical telescopes have yet to study the existence of atmospheric turbulence (AT). In this paper, we first experimentally investigate the sub-diffraction focusing of the SO light field in the atmospheric-like turbulence. The 137-element adaptive optics (AO) system is utilized to correct the dynamic wavefront aberration produced by the AT and obtain the AO closed-loop RMS of the residual wavefront error ∼λ/15. For a proofed telescope (clear aperture 12 mm and focal length 1000 mm) @λ=632.8 nm, the FWHM of the experimental SO spot under the modest AT (wavefront error RMS ∼0.57λ) is about 0.79 times of the Airy spot compared with the non-AT result of 0.76 times, while the strong AT (wavefront error RMS ∼1.35λ) erases the sub-diffraction focusing effect of the SO field and the average side-lobe intensity increases significantly. This study is promising for super-resolving telescope, synthetic aperture for visible imaging, etc.</div></div>","PeriodicalId":49719,"journal":{"name":"Optics and Lasers in Engineering","volume":"184 ","pages":"Article 108675"},"PeriodicalIF":3.5,"publicationDate":"2024-11-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142661501","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 : 2024-11-09DOI: 10.1016/j.optlaseng.2024.108682
A. Nakachi, S. Yokoyama, K. Iizuka, S. Yoneyama
A DIC-FEM hybrid method is proposed to capture micro-scale deformation behavior near the fiber-matrix interface by combining displacement distributions measured using digital image correlation (DIC) with finite element method (FEM) analysis. Images of CFRP cross section with fine random pattern before and after deformation are taken with a laser microscope. The in-plane displacement components near the interface of fiber and matrix are obtained using digital image correlation and they are used as the input of the hybrid method. Not only the displacement distributions but the strain fields are determined using the proposed hybrid method, based on the superposition principle, so that the same distributions are obtained as those obtained by the measurement. The proposed DIC-FEM hybrid provides the strains near the interface between fiber and matrix, compensating for the insufficient resolution of microscope images.
{"title":"A DIC-FEM hybrid method for measuring strains near fiber-matrix interface of CFRP cross section","authors":"A. Nakachi, S. Yokoyama, K. Iizuka, S. Yoneyama","doi":"10.1016/j.optlaseng.2024.108682","DOIUrl":"10.1016/j.optlaseng.2024.108682","url":null,"abstract":"<div><div>A DIC-FEM hybrid method is proposed to capture micro-scale deformation behavior near the fiber-matrix interface by combining displacement distributions measured using digital image correlation (DIC) with finite element method (FEM) analysis. Images of CFRP cross section with fine random pattern before and after deformation are taken with a laser microscope. The in-plane displacement components near the interface of fiber and matrix are obtained using digital image correlation and they are used as the input of the hybrid method. Not only the displacement distributions but the strain fields are determined using the proposed hybrid method, based on the superposition principle, so that the same distributions are obtained as those obtained by the measurement. The proposed DIC-FEM hybrid provides the strains near the interface between fiber and matrix, compensating for the insufficient resolution of microscope images.</div></div>","PeriodicalId":49719,"journal":{"name":"Optics and Lasers in Engineering","volume":"184 ","pages":"Article 108682"},"PeriodicalIF":3.5,"publicationDate":"2024-11-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142661587","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}
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