Pub Date : 2024-10-09DOI: 10.1016/j.optlaseng.2024.108631
Xingyu Yang , Zijian Zhang , Xinhua Li , Hungyen Lin , Samuel Lawman , Stoyan Stoyanov , Timothy Tilford , Yihua Hu , Yaochun Shen , Yalin Zheng
The applications of Optical Coherence Tomography (OCT) systems have been extensively explored in clinical settings and have attracted growing interest in other fields. Factors such as speed and cost are often prioritized over high resolution and power efficiency in industrial applications. Modern OCT systems typically operate at speeds between 20k-70k A-scans/s and are priced at least $50k. We report a line-field OCT with a high imaging speed of 430k A-scans/s, by operating a 2D camera in 8-bit mode, at a cost of $3.2k. The reported OCT system provides an axial resolution of 9 µm in air and achieves a maximum on-axis signal-to-noise ratio and sensitivity of 68.8 dB and 88.8 dB, respectively. We demonstrate the practical use of the system by measuring, visualizing, and segmenting samples of Printed Circuit Boards, pharmaceutical tablets, and pea seeds.
光学相干断层扫描（OCT）系统的应用已在临床环境中得到广泛探索，并在其他领域引起了越来越多的兴趣。在工业应用中，速度和成本等因素往往优先于高分辨率和能效。现代 OCT 系统的运行速度通常在 20k-70k A-scan/s 之间，价格至少在 5 万美元以上。我们报告了一种线场 OCT 系统，通过在 8 位模式下运行二维相机，成像速度高达 430k A-scan/s，成本仅为 3.2 千美元。报告中的 OCT 系统在空气中的轴向分辨率为 9 µm，最大轴向信噪比和灵敏度分别达到 68.8 dB 和 88.8 dB。我们通过测量、观察和分割印刷电路板、药片和豌豆种子样品，展示了该系统的实际应用。
{"title":"High-speed low-cost line-field spectral-domain optical coherence tomography for industrial applications","authors":"Xingyu Yang , Zijian Zhang , Xinhua Li , Hungyen Lin , Samuel Lawman , Stoyan Stoyanov , Timothy Tilford , Yihua Hu , Yaochun Shen , Yalin Zheng","doi":"10.1016/j.optlaseng.2024.108631","DOIUrl":"10.1016/j.optlaseng.2024.108631","url":null,"abstract":"<div><div>The applications of Optical Coherence Tomography (OCT) systems have been extensively explored in clinical settings and have attracted growing interest in other fields. Factors such as speed and cost are often prioritized over high resolution and power efficiency in industrial applications. Modern OCT systems typically operate at speeds between 20k-70k A-scans/s and are priced at least $50k. We report a line-field OCT with a high imaging speed of 430k A-scans/s, by operating a 2D camera in 8-bit mode, at a cost of $3.2k. The reported OCT system provides an axial resolution of 9 µm in air and achieves a maximum on-axis signal-to-noise ratio and sensitivity of 68.8 dB and 88.8 dB, respectively. We demonstrate the practical use of the system by measuring, visualizing, and segmenting samples of Printed Circuit Boards, pharmaceutical tablets, and pea seeds.</div></div>","PeriodicalId":49719,"journal":{"name":"Optics and Lasers in Engineering","volume":"184 ","pages":"Article 108631"},"PeriodicalIF":3.5,"publicationDate":"2024-10-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142418702","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 : 2024-10-08DOI: 10.1016/j.optlaseng.2024.108626
Jianglin Dai , Xiaochuan Ji , Xinshang Niu , Hongfei Jiao , Xinbin Cheng , Zhanshan Wang , Jinlong Zhang
The modern design of high-performance optical coatings demands a comprehensive consideration of multiple properties. We propose an efficient multi-objective optimization method utilizing an adaptive weighted sum method, exploring the lexicographic optimization and geometry-based adaptive weights determination method. Broadband negative dispersive mirrors have been designed that demonstrates notable improvements in performances of spectrum, group delay dispersion and electric field distribution. In addition, we employ Deep-learning method to enhance the optimization. The mapping between different design parameters and results has been learned, which helps the optimization to directly approach the optimal design. It extends the novel method to diverse designs utilizing the similar kinds of merit functions and subsequently accelerates the design by 120 times.
{"title":"Efficient multi-objective design method for optical coatings","authors":"Jianglin Dai , Xiaochuan Ji , Xinshang Niu , Hongfei Jiao , Xinbin Cheng , Zhanshan Wang , Jinlong Zhang","doi":"10.1016/j.optlaseng.2024.108626","DOIUrl":"10.1016/j.optlaseng.2024.108626","url":null,"abstract":"<div><div>The modern design of high-performance optical coatings demands a comprehensive consideration of multiple properties. We propose an efficient multi-objective optimization method utilizing an adaptive weighted sum method, exploring the lexicographic optimization and geometry-based adaptive weights determination method. Broadband negative dispersive mirrors have been designed that demonstrates notable improvements in performances of spectrum, group delay dispersion and electric field distribution. In addition, we employ Deep-learning method to enhance the optimization. The mapping between different design parameters and results has been learned, which helps the optimization to directly approach the optimal design. It extends the novel method to diverse designs utilizing the similar kinds of merit functions and subsequently accelerates the design by 120 times.</div></div>","PeriodicalId":49719,"journal":{"name":"Optics and Lasers in Engineering","volume":"184 ","pages":"Article 108626"},"PeriodicalIF":3.5,"publicationDate":"2024-10-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142418701","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 : 2024-10-07DOI: 10.1016/j.optlaseng.2024.108628
Shang Gao (高 尚) , María del Mar Sánchez-López , Ignacio Moreno
In this work we analyze diffraction gratings displayed on a pixelated spatial light modulator (SLM) at its spatial resolution limit (Nyquist limit) i.e., with largest diffraction angle, where the binary phase profile is the only alternative. Their implementation is influenced by the effect of a envelope and the multiple replicas of the diffraction pattern that arise from the SLM pixelation, where the fill factor plays an essential role. We use the Fourier transform theory to analyze the binary phase grating in a pixelated device in terms of the pixel size, fill factor and phase difference between the two levels in the grating. This convolutional approach probes very useful to gain physical insight of the different contributions to the diffraction orders, and analytical expressions for the complex amplitude coefficients and intensities are obtained. Experimental verification is provided by encoding binary phase triplicator gratings with different periods on a high-resolution liquid-crystal on silicon SLM. The effect of the device pixelation and pixel crosstalk on the diffraction efficiency and on the conditions to obtain a Nyquist triplicator phase grating are studied. These results can be interesting for applications requiring programmable and large beam steering angles.
{"title":"Analysis of diffraction gratings displayed in spatial light modulators at the Nyquist limit: Application to the triplicator grating","authors":"Shang Gao (高 尚) , María del Mar Sánchez-López , Ignacio Moreno","doi":"10.1016/j.optlaseng.2024.108628","DOIUrl":"10.1016/j.optlaseng.2024.108628","url":null,"abstract":"<div><div>In this work we analyze diffraction gratings displayed on a pixelated spatial light modulator (SLM) at its spatial resolution limit (Nyquist limit) i.e., with largest diffraction angle, where the binary phase profile is the only alternative. Their implementation is influenced by the effect of a <span><math><mtext>sinc</mtext></math></span> envelope and the multiple replicas of the diffraction pattern that arise from the SLM pixelation, where the fill factor plays an essential role. We use the Fourier transform theory to analyze the binary phase grating in a pixelated device in terms of the pixel size, fill factor and phase difference between the two levels in the grating. This convolutional approach probes very useful to gain physical insight of the different contributions to the diffraction orders, and analytical expressions for the complex amplitude coefficients and intensities are obtained. Experimental verification is provided by encoding binary phase triplicator gratings with different periods on a high-resolution liquid-crystal on silicon SLM. The effect of the device pixelation and pixel crosstalk on the diffraction efficiency and on the conditions to obtain a Nyquist triplicator phase grating are studied. These results can be interesting for applications requiring programmable and large beam steering angles.</div></div>","PeriodicalId":49719,"journal":{"name":"Optics and Lasers in Engineering","volume":"184 ","pages":"Article 108628"},"PeriodicalIF":3.5,"publicationDate":"2024-10-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142418700","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 : 2024-10-07DOI: 10.1016/j.optlaseng.2024.108618
Monideepa Mukherjee
Laser based directed energy deposition (L-DED) is an additive manufacturing process in which laser energy is used to fuse powder feedstock by melting while being deposited in a layer-by-layer manner, to produce three dimensional (3D) components. The quality of parts produced through this process depends on numerous process parameters. In the present work, the combined effects of defocussing distance, laser power and scanning speed on the geometrical characteristics of single line clads of AISI SS316L stainless steel and H13 tool steel powders produced through L-DED, was investigated. Theoretical analysis of the mutual interactions between laser, powder and substrate was used to explain the variations in clad geometry and deposition behaviour of the two steels. Process parameter maps were developed for the two steels and the influence of defocussing distance on optimal process parameter windows was evaluated. The work demonstrates that laser defocussing distance can be used as a simple but effective method to enhance the flexibility of the deposition process.
{"title":"Significance of defocussing distance in laser based directed energy deposition of steel powders: Effect on clad geometrical characteristics and process parameter maps.","authors":"Monideepa Mukherjee","doi":"10.1016/j.optlaseng.2024.108618","DOIUrl":"10.1016/j.optlaseng.2024.108618","url":null,"abstract":"<div><div>Laser based directed energy deposition (L-DED) is an additive manufacturing process in which laser energy is used to fuse powder feedstock by melting while being deposited in a layer-by-layer manner, to produce three dimensional (3D) components. The quality of parts produced through this process depends on numerous process parameters. In the present work, the combined effects of defocussing distance, laser power and scanning speed on the geometrical characteristics of single line clads of AISI SS316L stainless steel and H13 tool steel powders produced through L-DED, was investigated. Theoretical analysis of the mutual interactions between laser, powder and substrate was used to explain the variations in clad geometry and deposition behaviour of the two steels. Process parameter maps were developed for the two steels and the influence of defocussing distance on optimal process parameter windows was evaluated. The work demonstrates that laser defocussing distance can be used as a simple but effective method to enhance the flexibility of the deposition process.</div></div>","PeriodicalId":49719,"journal":{"name":"Optics and Lasers in Engineering","volume":"184 ","pages":"Article 108618"},"PeriodicalIF":3.5,"publicationDate":"2024-10-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142418710","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 : 2024-10-07DOI: 10.1016/j.optlaseng.2024.108624
Kaiqi Lang , Jiaqing Qiang , Yuyi Qiu , Xiaoping Wang
Holography is widely used for imaging plankton because of its large depth of field. Autofocusing is a critical step in holographic imaging, where the optimal focal plane is determined by locating the extremum of the evaluation function curve. However, most of these methods perform auto-focusing on single focus holograms. To apply these methods to multi-focus holograms, the hologram must be subjected to object segmentation. It is difficult to achieve good results when focusing on holograms with small objects and large depth of field. Therefore, we propose a multi-focus autofocus method based on connected domain analysis (CDA), which allows focusing on multiple objects at different focal lengths simultaneously without image segmentation. Each object generates a focus evaluation curve, resulting in high focusing accuracy. We set up an in-line holographic optical system with a 30 mm depth of field and recorded holograms of Nauplius, Cladocera, Rotifera, Copepods, Noctiluca scintillans and real seawater samples. We demonstrated the robustness of the CDA algorithm for different target types and its effectiveness in focusing multi-focus images by applying it to holograms of six types of samples.
{"title":"Autofocusing method for multifocal holograms based on connected domain analysis","authors":"Kaiqi Lang , Jiaqing Qiang , Yuyi Qiu , Xiaoping Wang","doi":"10.1016/j.optlaseng.2024.108624","DOIUrl":"10.1016/j.optlaseng.2024.108624","url":null,"abstract":"<div><div>Holography is widely used for imaging plankton because of its large depth of field. Autofocusing is a critical step in holographic imaging, where the optimal focal plane is determined by locating the extremum of the evaluation function curve. However, most of these methods perform auto-focusing on single focus holograms. To apply these methods to multi-focus holograms, the hologram must be subjected to object segmentation. It is difficult to achieve good results when focusing on holograms with small objects and large depth of field. Therefore, we propose a multi-focus autofocus method based on connected domain analysis (CDA), which allows focusing on multiple objects at different focal lengths simultaneously without image segmentation. Each object generates a focus evaluation curve, resulting in high focusing accuracy. We set up an in-line holographic optical system with a 30 mm depth of field and recorded holograms of <em>Nauplius, Cladocera, Rotifera, Copepods, Noctiluca scintillans</em> and real seawater samples. We demonstrated the robustness of the CDA algorithm for different target types and its effectiveness in focusing multi-focus images by applying it to holograms of six types of samples.</div></div>","PeriodicalId":49719,"journal":{"name":"Optics and Lasers in Engineering","volume":"184 ","pages":"Article 108624"},"PeriodicalIF":3.5,"publicationDate":"2024-10-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142418619","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 : 2024-10-07DOI: 10.1016/j.optlaseng.2024.108611
Sourav Chandra, Rakesh Kumar Singh
Characterization of statistical properties of a vector source requires fast and efficient measurement of all four elements of the square coherence-polarization (BCP) matrix. Here, we report a new experimental technique for measuring the BCP matrix of the stochastic field using a single-intensity recording. A detailed theoretical framework is presented to measure the elements of the BCP matrix of vector source through polarization correlation of the first two Stokes parameters (SPs), S0 and S1. We validate our technique through numerical simulations followed by proof-of-principle experiments. Experimental demonstration is performed by employing a specially designed folded interferometer to coherently sum a vector random field with a known reference and subsequently leverage a tuneable beam displacer to capture the orthogonal polarization components to determine the first two SPs in a single-frame recording. A correlation of these two SPs and their Fourier processing enables the extraction of all four elements of the BCP matrix from a single-intensity recording. The viability of our experimental technique is demonstrated by measuring all four elements of the BCP matrix for three different vector sources in the far-field. A good agreement between simulation and experimental results confirms the accuracy of the proposed technique. This method will find applications in the characterization of light fields, evaluating the polarization dynamics, looking through randomness, etc.
{"title":"Measurement of coherence-polarization matrix from a single-frame recording","authors":"Sourav Chandra, Rakesh Kumar Singh","doi":"10.1016/j.optlaseng.2024.108611","DOIUrl":"10.1016/j.optlaseng.2024.108611","url":null,"abstract":"<div><div>Characterization of statistical properties of a vector source requires fast and efficient measurement of all four elements of the square coherence-polarization (BCP) matrix. Here, we report a new experimental technique for measuring the BCP matrix of the stochastic field using a single-intensity recording. A detailed theoretical framework is presented to measure the elements of the BCP matrix of vector source through polarization correlation of the first two Stokes parameters (SPs), S<sub>0</sub> and S<sub>1</sub>. We validate our technique through numerical simulations followed by proof-of-principle experiments. Experimental demonstration is performed by employing a specially designed folded interferometer to coherently sum a vector random field with a known reference and subsequently leverage a tuneable beam displacer to capture the orthogonal polarization components to determine the first two SPs in a single-frame recording. A correlation of these two SPs and their Fourier processing enables the extraction of all four elements of the BCP matrix from a single-intensity recording. The viability of our experimental technique is demonstrated by measuring all four elements of the BCP matrix for three different vector sources in the far-field. A good agreement between simulation and experimental results confirms the accuracy of the proposed technique. This method will find applications in the characterization of light fields, evaluating the polarization dynamics, looking through randomness, etc.</div></div>","PeriodicalId":49719,"journal":{"name":"Optics and Lasers in Engineering","volume":"184 ","pages":"Article 108611"},"PeriodicalIF":3.5,"publicationDate":"2024-10-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142418699","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 : 2024-10-05DOI: 10.1016/j.optlaseng.2024.108629
Xuebin Liu, Yuang Chen, Chongji Zhao, Jie Yang, Huan Deng
The limited depth of field (DOF) inherent in cameras often results in defocused and blurry backgrounds when capturing images in large aperture mode. This not only leads to the loss of crucial background information but also impedes the efficient reconstruction of the background regions. Usually, super-resolution (SR) techniques struggle to produce high-quality results for images captured with large apertures. To enhance the reconstruction quality of defocused regions in large aperture images, a foreground-background separation and deblurring super-resolution (FBSDSR) method was proposed in this paper. Based on the idea of foreground-background separation processing, we first divide the large aperture image into a sharp foreground region (If) and a blurry background region (Ib) based on depth information. The background region (Ib) is then deblurred using an end-to-end iterative filter adaptive network (IFAN). This deblurring process refocuses the background, ultimately restoring an image with sharp details throughout. Finally, the enhanced super-resolution generative adversarial networks (Real-ESRGAN) which specializes in images SR of realistic scenes was used to process the sharp all-in-focus image. This method results in high-quality reconstructions of both the foreground and background of large aperture images. The experimental results demonstrated that the proposed method achieved effective reconstruction of the entire large aperture images clearly, overcoming the limitations of existing methods that struggle to reconstruct defocused regions. This significantly enhances the quality and resolution of large aperture images. Specifically, when FBSDSR is integrated with Real-ESRGAN, the PSNR, LPIPS, NIQE, and hyperIQA metrics were improved by approximately 2.2 %, 45.1 %, 34.7 %, and 10.9 % respectively.
{"title":"Foreground-background separation and deblurring super-resolution method","authors":"Xuebin Liu, Yuang Chen, Chongji Zhao, Jie Yang, Huan Deng","doi":"10.1016/j.optlaseng.2024.108629","DOIUrl":"10.1016/j.optlaseng.2024.108629","url":null,"abstract":"<div><div>The limited depth of field (DOF) inherent in cameras often results in defocused and blurry backgrounds when capturing images in large aperture mode. This not only leads to the loss of crucial background information but also impedes the efficient reconstruction of the background regions. Usually, super-resolution (SR) techniques struggle to produce high-quality results for images captured with large apertures. To enhance the reconstruction quality of defocused regions in large aperture images, a foreground-background separation and deblurring super-resolution (FBSDSR) method was proposed in this paper. Based on the idea of foreground-background separation processing, we first divide the large aperture image into a sharp foreground region (I<sub>f</sub>) and a blurry background region (I<sub>b</sub>) based on depth information. The background region (I<sub>b</sub>) is then deblurred using an end-to-end iterative filter adaptive network (IFAN). This deblurring process refocuses the background, ultimately restoring an image with sharp details throughout. Finally, the enhanced super-resolution generative adversarial networks (Real-ESRGAN) which specializes in images SR of realistic scenes was used to process the sharp all-in-focus image. This method results in high-quality reconstructions of both the foreground and background of large aperture images. The experimental results demonstrated that the proposed method achieved effective reconstruction of the entire large aperture images clearly, overcoming the limitations of existing methods that struggle to reconstruct defocused regions. This significantly enhances the quality and resolution of large aperture images. Specifically, when FBSDSR is integrated with Real-ESRGAN, the PSNR, LPIPS, NIQE, and hyperIQA metrics were improved by approximately 2.2 %, 45.1 %, 34.7 %, and 10.9 % respectively.</div></div>","PeriodicalId":49719,"journal":{"name":"Optics and Lasers in Engineering","volume":"184 ","pages":"Article 108629"},"PeriodicalIF":3.5,"publicationDate":"2024-10-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142418650","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 : 2024-10-05DOI: 10.1016/j.optlaseng.2024.108621
Bin Hou, Zao Yi, Qianju Song
Previous studies on refractive index sensors have shown that their sensing characteristics are limited by variations in the background environment refractive index, resulting in a significant decrease in the figure of merit (FOM) and sensitivity of the sensor. Here, we design a high-Q refractive index sensor, which is composed of a Dirac semimetal. The proposed sensor is based on topological bound states in the continuum (BICs), which have a diverging quality factor, and exhibits extremely high FOM and detection sensitivity over a wide variation range of the background environment refractive index. Its operation is based on the reciprocating motion of two pairs of BICs in the kx and ky high-symmetry lines of the momentum space. Specifically, two pairs of BICs, which are characterized by topological charges, can be merged and generated by varying the Fermi energy of the Dirac semimetal. Furthermore, we extract the relation between the Fermi energy and the background environment refractive index for the merging-BIC. This ensures that the FOM is extremely high over a very wide variation range of the background environment refractive index. Our findings provide a perspective for investigating ultrahigh performance refractive index sensors based on merging-BICs.
{"title":"High-Q refractive index sensor with an ultrawide detection range based on topological bound states in the continuum","authors":"Bin Hou, Zao Yi, Qianju Song","doi":"10.1016/j.optlaseng.2024.108621","DOIUrl":"10.1016/j.optlaseng.2024.108621","url":null,"abstract":"<div><div>Previous studies on refractive index sensors have shown that their sensing characteristics are limited by variations in the background environment refractive index, resulting in a significant decrease in the figure of merit (FOM) and sensitivity of the sensor. Here, we design a high-Q refractive index sensor, which is composed of a Dirac semimetal. The proposed sensor is based on topological bound states in the continuum (BICs), which have a diverging quality factor, and exhibits extremely high FOM and detection sensitivity over a wide variation range of the background environment refractive index. Its operation is based on the reciprocating motion of two pairs of BICs in the <em>k</em><sub><em>x</em></sub> and <em>k</em><sub><em>y</em></sub> high-symmetry lines of the momentum space. Specifically, two pairs of BICs, which are characterized by topological charges, can be merged and generated by varying the Fermi energy of the Dirac semimetal. Furthermore, we extract the relation between the Fermi energy and the background environment refractive index for the merging-BIC. This ensures that the FOM is extremely high over a very wide variation range of the background environment refractive index. Our findings provide a perspective for investigating ultrahigh performance refractive index sensors based on merging-BICs.</div></div>","PeriodicalId":49719,"journal":{"name":"Optics and Lasers in Engineering","volume":"184 ","pages":"Article 108621"},"PeriodicalIF":3.5,"publicationDate":"2024-10-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142418708","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 : 2024-10-05DOI: 10.1016/j.optlaseng.2024.108616
Huiyang Wang , Tianzhi Wen , Shengde Liu , Hongzhan Liu , Migao Li , Xiaoxu Lu
Achieving high quality 3D imaging with single exposure has always been the goal of Fresnel incoherent correlation digital holography (FINCH). However, there is a trade-off between space-time bandwidth product and system complexity, resulting in lower reconstruction quality of FINCH. Here, we propose a single-shot FINCH method based on digital self-calibrated point source holograms (PSHs) to achieve dynamic 3D imaging. Firstly, it demonstrates that a single FINCH hologram integrates information from multiple incoherently superimposed PSHs, so that the reconstructed images exhibit significant sparsity variations in the gradient domain when correlated with the PSHs to be calibrated. As a result, we can conveniently achieve accurate PSHs of objects at different depth planes by digital self-calibration algorithm. Furthermore, by combining the digital self-calibrated PSHs with a compressive sensing (CS) reconstruction algorithm, the quality of the 3D reconstruction can be effectively enhanced, showing excellent performance in improving lateral and axial resolution. Importantly, this method offers a new strategy for simplifying implementation system and improving space-time bandwidth product of FINCH technology, and then achieves high quality 3D imaging of dynamic scene.
{"title":"Single-shot Fresnel incoherent correlation holography based on digital self-calibrated point source holograms","authors":"Huiyang Wang , Tianzhi Wen , Shengde Liu , Hongzhan Liu , Migao Li , Xiaoxu Lu","doi":"10.1016/j.optlaseng.2024.108616","DOIUrl":"10.1016/j.optlaseng.2024.108616","url":null,"abstract":"<div><div>Achieving high quality 3D imaging with single exposure has always been the goal of Fresnel incoherent correlation digital holography (FINCH). However, there is a trade-off between space-time bandwidth product and system complexity, resulting in lower reconstruction quality of FINCH. Here, we propose a single-shot FINCH method based on digital self-calibrated point source holograms (PSHs) to achieve dynamic 3D imaging. Firstly, it demonstrates that a single FINCH hologram integrates information from multiple incoherently superimposed PSHs, so that the reconstructed images exhibit significant sparsity variations in the gradient domain when correlated with the PSHs to be calibrated. As a result, we can conveniently achieve accurate PSHs of objects at different depth planes by digital self-calibration algorithm. Furthermore, by combining the digital self-calibrated PSHs with a compressive sensing (CS) reconstruction algorithm, the quality of the 3D reconstruction can be effectively enhanced, showing excellent performance in improving lateral and axial resolution. Importantly, this method offers a new strategy for simplifying implementation system and improving space-time bandwidth product of FINCH technology, and then achieves high quality 3D imaging of dynamic scene.</div></div>","PeriodicalId":49719,"journal":{"name":"Optics and Lasers in Engineering","volume":"184 ","pages":"Article 108616"},"PeriodicalIF":3.5,"publicationDate":"2024-10-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142418709","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 : 2024-10-04DOI: 10.1016/j.optlaseng.2024.108609
Jack Girard, Song Zhang
This paper presents a novel method to speed up error detection in an additive manufacturing (AM) process by minimizing the necessary three-dimensional (3D) reconstruction and comparison. We develop a structured light 3D imaging technique that has native pixel-by-pixel mapping between the captured two-dimensional (2D) image and the reconstructed 3D point cloud. This 3D imaging technique allows error detection to be performed in the 2D image domain prior to 3D point cloud generation, which drastically reduces complexity and computational time. Compared to an existing AM error detection method based on 3D reconstruction and point cloud processing, experimental results from a material extrusion (MEX) AM process demonstrate that our proposed method significantly increases the error detection speed.
本文提出了一种新方法，通过最大限度地减少必要的三维（3D）重建和比较，加快增材制造（AM）工艺中的误差检测。我们开发了一种结构光三维成像技术，该技术可在捕获的二维（2D）图像和重建的三维点云之间进行原生逐像素映射。这种三维成像技术允许在生成三维点云之前在二维图像域中进行误差检测，从而大大降低了复杂性和计算时间。与基于三维重建和点云处理的现有 AM 错误检测方法相比，材料挤压 (MEX) AM 过程的实验结果表明，我们提出的方法显著提高了错误检测速度。
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