Pub Date : 2026-06-01Epub Date: 2026-02-12DOI: 10.1016/j.optlaseng.2026.109685
Zinan Huang, Menghao Jia, Jixin Qiu, Bijun Xu, Xiaogang Wang
We propose an optical encryption scheme that utilizes single-pixel imaging (SPI) with Hermite-Gaussian (HG) Illumination through dynamic scattering. In the encryption process, two images containing the parameters used to generate the HG patterns are converted into a single hologram using the gradient descent algorithm. Then, both the HG patterns and the hologram are combined to form the illumination pattern sequence for encrypting the secret image through a dynamic scattering medium in the SPI system. After that, the collected bucket signals are digitally fused with the hologram data to generate the ciphertext. During the decryption process, the bucket signal and the hologram are first extracted from the ciphertext. The parameters within the two original images can be holographically reconstructed, which subsequently allows for the generation of the HG patterns. Subsequently, the extracted bucket signal undergoes a correction algorithm to remove the disturbances caused by the dynamic scattering medium. Finally, the HG patterns and the rectified bucket signal jointly reconstruct the target secret image. Experimental results are presented to validate the effectiveness and security of the proposed scheme.
{"title":"Dynamic scattering medium-assisted optical encryption using single-pixel imaging with Hermite-Gaussian illumination","authors":"Zinan Huang, Menghao Jia, Jixin Qiu, Bijun Xu, Xiaogang Wang","doi":"10.1016/j.optlaseng.2026.109685","DOIUrl":"10.1016/j.optlaseng.2026.109685","url":null,"abstract":"<div><div>We propose an optical encryption scheme that utilizes single-pixel imaging (SPI) with Hermite-Gaussian (HG) Illumination through dynamic scattering. In the encryption process, two images containing the parameters used to generate the HG patterns are converted into a single hologram using the gradient descent algorithm. Then, both the HG patterns and the hologram are combined to form the illumination pattern sequence for encrypting the secret image through a dynamic scattering medium in the SPI system. After that, the collected bucket signals are digitally fused with the hologram data to generate the ciphertext. During the decryption process, the bucket signal and the hologram are first extracted from the ciphertext. The parameters within the two original images can be holographically reconstructed, which subsequently allows for the generation of the HG patterns. Subsequently, the extracted bucket signal undergoes a correction algorithm to remove the disturbances caused by the dynamic scattering medium. Finally, the HG patterns and the rectified bucket signal jointly reconstruct the target secret image. Experimental results are presented to validate the effectiveness and security of the proposed scheme.</div></div>","PeriodicalId":49719,"journal":{"name":"Optics and Lasers in Engineering","volume":"201 ","pages":"Article 109685"},"PeriodicalIF":3.7,"publicationDate":"2026-06-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146189439","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}
Optical microscopy is a pivotal technique for biomedical discovery, yet many high-performance instruments remain bulky and poorly suited for live-cell imaging and on-site computational analysis. This limits their accessibility and practical use in experiments requiring quantitative assessment of cellular dynamics. To address these challenges, we present a compact benchtop microscope that integrates an electrically tunable liquid lens (ETL), transport-of-intensity-equation (TIE)–based phase imaging, and edge-based artificial intelligence (AI) analysis within a single platform. A compact 2 × objective combined with an electrowetting ETL enables rapid, vibration-free axial defocus control with a measured magnification variation of 3.3 ± 0.2% over a 5.9 mm focal range, facilitating electronic acquisition of defocused intensity images required for TIE-based phase recovery. The 20 cm-tall modular system incorporates transparent heater–based environmental control for microfluidic cell culture and supports optional dual-channel fluorescence and wide-field imaging modules. For automated analysis, the microscope is coupled to an edge AI device that performs on-device cell segmentation, classification, and tracking from in-focus bright-field images using a convolutional neural network. By combining ETL-based electronic defocus, non-interferometric phase imaging, and edge-based bright-field image analysis in a compact form factor, the system provides label-free phase visualization alongside low-latency AI-assisted analysis, offering a practical and compact personal microscopy solution for research, education, and training applications.
{"title":"Electrically tunable benchtop microscope integrating TIE-based phase imaging and edge AI analysis","authors":"Hsieh-Fu Tsai , Soumyajit Podder , I-Ming Chang , Mao-Chang Ho","doi":"10.1016/j.optlaseng.2026.109659","DOIUrl":"10.1016/j.optlaseng.2026.109659","url":null,"abstract":"<div><div>Optical microscopy is a pivotal technique for biomedical discovery, yet many high-performance instruments remain bulky and poorly suited for live-cell imaging and on-site computational analysis. This limits their accessibility and practical use in experiments requiring quantitative assessment of cellular dynamics. To address these challenges, we present a compact benchtop microscope that integrates an electrically tunable liquid lens (ETL), transport-of-intensity-equation (TIE)–based phase imaging, and edge-based artificial intelligence (AI) analysis within a single platform. A compact 2 × objective combined with an electrowetting ETL enables rapid, vibration-free axial defocus control with a measured magnification variation of 3.3 ± 0.2% over a 5.9 mm focal range, facilitating electronic acquisition of defocused intensity images required for TIE-based phase recovery. The 20 cm-tall modular system incorporates transparent heater–based environmental control for microfluidic cell culture and supports optional dual-channel fluorescence and wide-field imaging modules. For automated analysis, the microscope is coupled to an edge AI device that performs on-device cell segmentation, classification, and tracking from in-focus bright-field images using a convolutional neural network. By combining ETL-based electronic defocus, non-interferometric phase imaging, and edge-based bright-field image analysis in a compact form factor, the system provides label-free phase visualization alongside low-latency AI-assisted analysis, offering a practical and compact personal microscopy solution for research, education, and training applications.</div></div>","PeriodicalId":49719,"journal":{"name":"Optics and Lasers in Engineering","volume":"201 ","pages":"Article 109659"},"PeriodicalIF":3.7,"publicationDate":"2026-06-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146189771","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 : 2026-06-01Epub Date: 2026-01-19DOI: 10.1016/j.optlaseng.2026.109636
Di Yang , Zhuoqun Yuan , Xinyi Li , Yapeng Sun , Qiunan Yang , Yanmei Liang
Surface topography influences the functional properties of material interfaces, including optical, mechanical, and biological properties. Nanoscale topographic measurement is essential for precision manufacturing and surface defect analysis. While optical coherence tomography (OCT) offers a millimeter-scale field of view without mechanical scanning, its effective topographic measurement range is limited by a shallow depth of focus. Defocusing could degrade the accuracy and resolution of the topographic measurement. To address this limitation, we proposed an automatic refocusing method for nanoscale topographic measurement with a large axial measurement range. By analyzing the frequency of topographic information, we identified a robust frequency feature, termed averaging low-frequency intensity, that enables precise estimation of defocus distance. Based on this, a refocusing algorithm is developed to automatically determine and correct defocus without additional hardware. Experimental results of a USAF resolution target demonstrated that the proposed method can extend the axial measurement range up to six times the depth of focus while preserving lateral resolution and suppressing side lobes. Further validation on scratched glass showed that the method can accurately recover nanoscale surface damage at a 6 times defocus position. Finally, the measurement results of the metal with a rough surface demonstrated that the proposed method can recover the nanoscale topography of complex samples under defocus. This approach offers a promising solution for high-precision surface profiling in industrial inspection and biomedical imaging.
{"title":"Automatic refocusing method for nanoscale topographic measurement by optical coherence tomography","authors":"Di Yang , Zhuoqun Yuan , Xinyi Li , Yapeng Sun , Qiunan Yang , Yanmei Liang","doi":"10.1016/j.optlaseng.2026.109636","DOIUrl":"10.1016/j.optlaseng.2026.109636","url":null,"abstract":"<div><div>Surface topography influences the functional properties of material interfaces, including optical, mechanical, and biological properties. Nanoscale topographic measurement is essential for precision manufacturing and surface defect analysis. While optical coherence tomography (OCT) offers a millimeter-scale field of view without mechanical scanning, its effective topographic measurement range is limited by a shallow depth of focus. Defocusing could degrade the accuracy and resolution of the topographic measurement. To address this limitation, we proposed an automatic refocusing method for nanoscale topographic measurement with a large axial measurement range. By analyzing the frequency of topographic information, we identified a robust frequency feature, termed averaging low-frequency intensity, that enables precise estimation of defocus distance. Based on this, a refocusing algorithm is developed to automatically determine and correct defocus without additional hardware. Experimental results of a USAF resolution target demonstrated that the proposed method can extend the axial measurement range up to six times the depth of focus while preserving lateral resolution and suppressing side lobes. Further validation on scratched glass showed that the method can accurately recover nanoscale surface damage at a 6 times defocus position. Finally, the measurement results of the metal with a rough surface demonstrated that the proposed method can recover the nanoscale topography of complex samples under defocus. This approach offers a promising solution for high-precision surface profiling in industrial inspection and biomedical imaging.</div></div>","PeriodicalId":49719,"journal":{"name":"Optics and Lasers in Engineering","volume":"201 ","pages":"Article 109636"},"PeriodicalIF":3.7,"publicationDate":"2026-06-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146039558","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 : 2026-06-01Epub Date: 2026-01-19DOI: 10.1016/j.optlaseng.2026.109631
Zhichen Tang , Canyu Zhu , Guanyu Cheng , Shihai Lan , Yong Su
Accurate characterization of spatial resolution is essential for assessing the performance of digital image correlation (DIC) methods. Inspired by the classical Rayleigh criterion, this study considers a double-step displacement field and defines the spatial resolution as the separation at which two adjacent displacement discontinuities can just be resolved in the measured strain field. Based on this definition, theoretical models are developed to quantify the spatial resolution. For conventional DIC with a subset size of , the spatial resolution for the first-order shape function is approximately , while that for the second-order shape function is about . For Gaussian-weighted DIC with a weighting radius of R, the spatial resolution is approximately 2R for the first-order shape function and 1.53R for the second-order shape function. The proposed criterion is further applied to deep learning-based DIC methods (e.g., U-DICNet, DICTr, and USDICNet) to demonstrate its universality. In summary, this work establishes a physically grounded and quantitatively reliable framework for evaluating spatial resolution in conventional, weighted, and learning-based DIC methods, with potential applications in performance assessment, algorithm optimization, and parameter selection.
{"title":"A criterion for assessing spatial resolution in digital image correlation: Applications to conventional, Gaussian-weighted, and deep learning-based methods","authors":"Zhichen Tang , Canyu Zhu , Guanyu Cheng , Shihai Lan , Yong Su","doi":"10.1016/j.optlaseng.2026.109631","DOIUrl":"10.1016/j.optlaseng.2026.109631","url":null,"abstract":"<div><div>Accurate characterization of spatial resolution is essential for assessing the performance of digital image correlation (DIC) methods. Inspired by the classical Rayleigh criterion, this study considers a double-step displacement field and defines the spatial resolution as the separation at which two adjacent displacement discontinuities can just be resolved in the measured strain field. Based on this definition, theoretical models are developed to quantify the spatial resolution. For conventional DIC with a subset size of <span><math><mrow><mn>2</mn><mi>M</mi><mo>+</mo><mn>1</mn></mrow></math></span>, the spatial resolution for the first-order shape function is approximately <span><math><mrow><mn>2</mn><mi>M</mi><mo>+</mo><mn>2</mn></mrow></math></span>, while that for the second-order shape function is about <span><math><mrow><mn>0.66</mn><mo>(</mo><mn>2</mn><mi>M</mi><mo>+</mo><mn>1</mn><mo>)</mo></mrow></math></span>. For Gaussian-weighted DIC with a weighting radius of <em>R</em>, the spatial resolution is approximately 2<em>R</em> for the first-order shape function and 1.53<em>R</em> for the second-order shape function. The proposed criterion is further applied to deep learning-based DIC methods (e.g., U-DICNet, DICTr, and USDICNet) to demonstrate its universality. In summary, this work establishes a physically grounded and quantitatively reliable framework for evaluating spatial resolution in conventional, weighted, and learning-based DIC methods, with potential applications in performance assessment, algorithm optimization, and parameter selection.</div></div>","PeriodicalId":49719,"journal":{"name":"Optics and Lasers in Engineering","volume":"201 ","pages":"Article 109631"},"PeriodicalIF":3.7,"publicationDate":"2026-06-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146039560","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 : 2026-06-01Epub Date: 2026-01-29DOI: 10.1016/j.optlaseng.2026.109662
Yanling Li , Feng Gao , Yongjia Xu , Matthew Hill , Yubo Ni , Nan Gao , Zhaozong Meng , Zonghua Zhang , Xiangqian Jiang
Geometric optics based optical phase measuring techniques, most prominently fringe projection profilometry (FPP) and phase measuring deflectometry (PMD), have been widely researched for three-dimensional (3D) shape measurement of both diffuse and specular surfaces owing to their advantages of non-contact, speed, and accuracy. FPP is well suited for the measurement of diffuse surfaces, while PMD excels in the measurement of specular surfaces. Various system models and calibration methods for the measurement of composite surfaces have been detailed in literature; however, a comparative overview of the strengths and weaknesses of viable measurement models, calibration methods and application scenarios are lacking. In this work, a review of the advancements in composite surface measurement is presented. Firstly, the fundamental principles of different models are reviewed and categorized, with a comparative analysis of their advantages, limitations, and future development directions. Then, existing calibration techniques are systematically summarized and classified according to their logical relationships, identifying their strengths, weaknesses, and remaining challenges to guide future research. Furthermore, accuracy verification and error compensation strategies for composite surface measurement systems are comprehensively summarized, revealing current research gaps. Finally, future development trends and potential research directions in composite surface measurement and calibration are discussed to address practical challenges such as in-situ measurement in industrial manufacturing, and to provide valuable insights for subsequent studies.
{"title":"Review of system modeling and calibration technologies for specular/diffuse composite surface metrology","authors":"Yanling Li , Feng Gao , Yongjia Xu , Matthew Hill , Yubo Ni , Nan Gao , Zhaozong Meng , Zonghua Zhang , Xiangqian Jiang","doi":"10.1016/j.optlaseng.2026.109662","DOIUrl":"10.1016/j.optlaseng.2026.109662","url":null,"abstract":"<div><div>Geometric optics based optical phase measuring techniques, most prominently fringe projection profilometry (FPP) and phase measuring deflectometry (PMD), have been widely researched for three-dimensional (3D) shape measurement of both diffuse and specular surfaces owing to their advantages of non-contact, speed, and accuracy. FPP is well suited for the measurement of diffuse surfaces, while PMD excels in the measurement of specular surfaces. Various system models and calibration methods for the measurement of composite surfaces have been detailed in literature; however, a comparative overview of the strengths and weaknesses of viable measurement models, calibration methods and application scenarios are lacking. In this work, a review of the advancements in composite surface measurement is presented. Firstly, the fundamental principles of different models are reviewed and categorized, with a comparative analysis of their advantages, limitations, and future development directions. Then, existing calibration techniques are systematically summarized and classified according to their logical relationships, identifying their strengths, weaknesses, and remaining challenges to guide future research. Furthermore, accuracy verification and error compensation strategies for composite surface measurement systems are comprehensively summarized, revealing current research gaps. Finally, future development trends and potential research directions in composite surface measurement and calibration are discussed to address practical challenges such as in-situ measurement in industrial manufacturing, and to provide valuable insights for subsequent studies.</div></div>","PeriodicalId":49719,"journal":{"name":"Optics and Lasers in Engineering","volume":"201 ","pages":"Article 109662"},"PeriodicalIF":3.7,"publicationDate":"2026-06-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146079584","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 : 2026-06-01Epub Date: 2026-02-09DOI: 10.1016/j.optlaseng.2026.109680
Mustafa Kirlar, Mustafa Turkmen
A theoretical analysis of an ultra-broadband metalens is presented. The proposed metalens, composed of tungsten disulfide (WS₂) nanofins positioned on a glass substrate, is capable of focusing light across an exceptionally wide spectral range from 450 to 1700 nm. WS₂ is chosen for its high refractive index and good optical performance within this range. The metalens is designed using the finite-difference time-domain (FDTD) method based on the Pancharatnam–Berry (P-B) phase principle. Unlike previous studies, this work demonstrates a single metalens design capable of broadband focusing across the 450–1700 nm wavelength range. The results reveal high and stable numerical aperture values across the designed wavelengths, along with a remarkable polarization conversion efficiency of up to 99.2 % for the metalens unit cell. Despite operating over a very broad bandwidth, the metalens achieves diffraction-limited focusing for nearly all designed wavelengths. Furthermore, it exhibits a focusing efficiency reaching 62 % and maintains a high numerical aperture of approximately 0.91, indicating excellent optical performance within the targeted range. Additionally, the chromatic aberration (3.3 %) remains very low across the 450–1700 nm spectrum. The demonstrated diffraction-limited focusing, minimal chromatic aberration, high numerical aperture, and outstanding polarization conversion efficiency (PCE) highlight the potential of this design for advanced nanophotonic applications in the visible and near-infrared regions.
{"title":"Ultra-broadband achromatic metalens based on polarization conversion metasurface","authors":"Mustafa Kirlar, Mustafa Turkmen","doi":"10.1016/j.optlaseng.2026.109680","DOIUrl":"10.1016/j.optlaseng.2026.109680","url":null,"abstract":"<div><div>A theoretical analysis of an ultra-broadband metalens is presented. The proposed metalens, composed of tungsten disulfide (WS₂) nanofins positioned on a glass substrate, is capable of focusing light across an exceptionally wide spectral range from 450 to 1700 nm. WS₂ is chosen for its high refractive index and good optical performance within this range. The metalens is designed using the finite-difference time-domain (FDTD) method based on the Pancharatnam–Berry (P-B) phase principle. Unlike previous studies, this work demonstrates a single metalens design capable of broadband focusing across the 450–1700 nm wavelength range. The results reveal high and stable numerical aperture values across the designed wavelengths, along with a remarkable polarization conversion efficiency of up to 99.2 % for the metalens unit cell. Despite operating over a very broad bandwidth, the metalens achieves diffraction-limited focusing for nearly all designed wavelengths. Furthermore, it exhibits a focusing efficiency reaching 62 % and maintains a high numerical aperture of approximately 0.91, indicating excellent optical performance within the targeted range. Additionally, the chromatic aberration (3.3 %) remains very low across the 450–1700 nm spectrum. The demonstrated diffraction-limited focusing, minimal chromatic aberration, high numerical aperture, and outstanding polarization conversion efficiency (PCE) highlight the potential of this design for advanced nanophotonic applications in the visible and near-infrared regions.</div></div>","PeriodicalId":49719,"journal":{"name":"Optics and Lasers in Engineering","volume":"201 ","pages":"Article 109680"},"PeriodicalIF":3.7,"publicationDate":"2026-06-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146189440","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 : 2026-06-01Epub Date: 2026-02-12DOI: 10.1016/j.optlaseng.2026.109681
Qichao Shen , Fangjun Xie , Shenghuan Jin , Donghui Zhang , Feng Wang , Yingjie Yu , Lin Chang
n advanced manufacturing and precision metrology, accurate measurement of the surface topography of each surface within transparent parallel optical components is crucial for controlling device performance. Multi-surface wavelength-tuned interferometry often suffers from spectral crowding and severe crosstalk due to the superposition of harmonic signals. Conventional FFT-based analysis is prone to spectral leakage under conditions of low signal-to-noise ratio (SNR) and non-integer period sampling, making it difficult to ensure measurement accuracy. To address these challenges, we propose a Hilbert-subspace Joint Parameter Estimation for Multi-surface Phase-shifting Interferometry (HJPE-MPI) algorithm. This algorithm utilizes the Hilbert transform to construct analytic signals, which are then used to form a Hankel matrix for subspace decomposition, enabling high-resolution frequency estimation of sampled interference signals. The estimated frequency offsets are subsequently used to correct the amplitude and phase of the harmonic components corresponding to each surface, thereby enabling joint and precise parameter localization. Simulation and experimental results demonstrate that the proposed method significantly outperforms conventional algorithms in the estimation accuracy of frequency, phase, and amplitude for multi-harmonic interference signals, and exhibits excellent repeatability and stability in measurements of a 30 mm-thick transparent plate.
{"title":"Subspace joint parameter estimation algorithm based on hilbert transform for constructing analytical signals in high-precision multi-surface phase-shifting interferometry","authors":"Qichao Shen , Fangjun Xie , Shenghuan Jin , Donghui Zhang , Feng Wang , Yingjie Yu , Lin Chang","doi":"10.1016/j.optlaseng.2026.109681","DOIUrl":"10.1016/j.optlaseng.2026.109681","url":null,"abstract":"<div><div>n advanced manufacturing and precision metrology, accurate measurement of the surface topography of each surface within transparent parallel optical components is crucial for controlling device performance. Multi-surface wavelength-tuned interferometry often suffers from spectral crowding and severe crosstalk due to the superposition of harmonic signals. Conventional FFT-based analysis is prone to spectral leakage under conditions of low signal-to-noise ratio (SNR) and non-integer period sampling, making it difficult to ensure measurement accuracy. To address these challenges, we propose a Hilbert-subspace Joint Parameter Estimation for Multi-surface Phase-shifting Interferometry (HJPE-MPI) algorithm. This algorithm utilizes the Hilbert transform to construct analytic signals, which are then used to form a Hankel matrix for subspace decomposition, enabling high-resolution frequency estimation of sampled interference signals. The estimated frequency offsets are subsequently used to correct the amplitude and phase of the harmonic components corresponding to each surface, thereby enabling joint and precise parameter localization. Simulation and experimental results demonstrate that the proposed method significantly outperforms conventional algorithms in the estimation accuracy of frequency, phase, and amplitude for multi-harmonic interference signals, and exhibits excellent repeatability and stability in measurements of a 30 mm-thick transparent plate.</div></div>","PeriodicalId":49719,"journal":{"name":"Optics and Lasers in Engineering","volume":"201 ","pages":"Article 109681"},"PeriodicalIF":3.7,"publicationDate":"2026-06-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146189438","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 : 2026-06-01Epub Date: 2026-01-31DOI: 10.1016/j.optlaseng.2026.109661
Chenbo Zhang , Guangjian Wang , Zongxing Gong , Hengyi Lei , Peng Gong
Fringe projection profilometry (FPP) is a widely employed non-contact 3D measurement technique. In a triangulation-based single-projector-camera configuration FPP system, phase establishes the pixel correspondence between the camera and projector to achieve 3D reconstruction. However, when measuring objects with complex textures, significant height jumps occur near reflectance discontinuity boundaries, substantially affecting measurement accuracy. Analysis indicates that camera defocusing and reflectance discontinuity jointly generate phase artifact error, leading to pixel matching error and ultimately causing height jump. From the perspective of reducing matching error, this paper proposes a height jump error compensation method based on epipolar constraint. First, a one-dimensional model of phase artifact error is established, and an analytical expression is derived, revealing the correlation of phase artifact error in orthogonal phase-shifting fringes with identical frequency. Based on this, the relationship between horizontal and vertical coordinate offset error in the projector coordinate system is derived, and iterative compensation is applied to the horizontal coordinate of the projector pixel in conjunction with epipolar constraint, effectively reducing matching error and improving the 3D measurement accuracy of complex textured objects. Quantitative and qualitative experiments demonstrate the effectiveness of the proposed method, with quantitative experiments showing that the proposed method reduces texture-induced height jump error by 67.33%.
{"title":"Improving 3D measurement accuracy of fringe projection profilometry for complex textured objects by reducing projector-camera pixel matching errors","authors":"Chenbo Zhang , Guangjian Wang , Zongxing Gong , Hengyi Lei , Peng Gong","doi":"10.1016/j.optlaseng.2026.109661","DOIUrl":"10.1016/j.optlaseng.2026.109661","url":null,"abstract":"<div><div>Fringe projection profilometry (FPP) is a widely employed non-contact 3D measurement technique. In a triangulation-based single-projector-camera configuration FPP system, phase establishes the pixel correspondence between the camera and projector to achieve 3D reconstruction. However, when measuring objects with complex textures, significant height jumps occur near reflectance discontinuity boundaries, substantially affecting measurement accuracy. Analysis indicates that camera defocusing and reflectance discontinuity jointly generate phase artifact error, leading to pixel matching error and ultimately causing height jump. From the perspective of reducing matching error, this paper proposes a height jump error compensation method based on epipolar constraint. First, a one-dimensional model of phase artifact error is established, and an analytical expression is derived, revealing the correlation of phase artifact error in orthogonal phase-shifting fringes with identical frequency. Based on this, the relationship between horizontal and vertical coordinate offset error in the projector coordinate system is derived, and iterative compensation is applied to the horizontal coordinate of the projector pixel in conjunction with epipolar constraint, effectively reducing matching error and improving the 3D measurement accuracy of complex textured objects. Quantitative and qualitative experiments demonstrate the effectiveness of the proposed method, with quantitative experiments showing that the proposed method reduces texture-induced height jump error by 67.33%.</div></div>","PeriodicalId":49719,"journal":{"name":"Optics and Lasers in Engineering","volume":"201 ","pages":"Article 109661"},"PeriodicalIF":3.7,"publicationDate":"2026-06-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146189769","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 : 2026-06-01Epub Date: 2026-02-02DOI: 10.1016/j.optlaseng.2026.109669
Yunmei Jiao , Huifeng Wang , Hao Du , Yuanhe Shan , Zefeng Pan , Chengyan Zhang , He Huang
Visual inspection of underwater infrastructure is severely hampered by image degradation from light scattering in turbid media, which obscures critical surface defects. To address this engineering challenge, this paper proposes a robust visual enhancement method based on polarization imaging. The proposed framework operates through two primary stages. The first stage involves physical parameter estimation, where a DoP-Guided Hierarchical Quadtree Background Light Estimation (DHQBLE) technique is developed, and scene depth is robustly estimated by jointly optimizing the red channel prior, the Polarization Gradient Direction Field (PGDF), and multi-channel attenuation differences. The second stage focuses on adaptive feature fusion, implemented through a Multi-scale Decomposition Fusion with Contrast Consistency (MDF-CC) framework that adaptively integrates intensity and polarization features to enhance image contrast and restore fine structural details. Comprehensive experiments were conducted on self-built and real-world underwater datasets, encompassing various defect types (cracks, holes, spalling) and environmental conditions (turbidity: 1.78–5.39 g/L; flow velocity: 2.65–4.42 m/s). The results demonstrate that the proposed method consistently outperforms state-of-the-art approaches, achieving superior quantitative (PSNR, SSIM, contrast, entropy) and qualitative performance. This confirms its effectiveness as a robust solution for high-fidelity optical inspection in complex underwater environments.
{"title":"Robust polarimetric image restoration for underwater concrete defect inspection in turbid environments","authors":"Yunmei Jiao , Huifeng Wang , Hao Du , Yuanhe Shan , Zefeng Pan , Chengyan Zhang , He Huang","doi":"10.1016/j.optlaseng.2026.109669","DOIUrl":"10.1016/j.optlaseng.2026.109669","url":null,"abstract":"<div><div>Visual inspection of underwater infrastructure is severely hampered by image degradation from light scattering in turbid media, which obscures critical surface defects. To address this engineering challenge, this paper proposes a robust visual enhancement method based on polarization imaging. The proposed framework operates through two primary stages. The first stage involves physical parameter estimation, where a DoP-Guided Hierarchical Quadtree Background Light Estimation (DHQBLE) technique is developed, and scene depth is robustly estimated by jointly optimizing the red channel prior, the Polarization Gradient Direction Field (PGDF), and multi-channel attenuation differences. The second stage focuses on adaptive feature fusion, implemented through a Multi-scale Decomposition Fusion with Contrast Consistency (MDF-CC) framework that adaptively integrates intensity and polarization features to enhance image contrast and restore fine structural details. Comprehensive experiments were conducted on self-built and real-world underwater datasets, encompassing various defect types (cracks, holes, spalling) and environmental conditions (turbidity: 1.78–5.39 g/L; flow velocity: 2.65–4.42 m/s). The results demonstrate that the proposed method consistently outperforms state-of-the-art approaches, achieving superior quantitative (PSNR, SSIM, contrast, entropy) and qualitative performance. This confirms its effectiveness as a robust solution for high-fidelity optical inspection in complex underwater environments.</div></div>","PeriodicalId":49719,"journal":{"name":"Optics and Lasers in Engineering","volume":"201 ","pages":"Article 109669"},"PeriodicalIF":3.7,"publicationDate":"2026-06-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146189768","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 : 2026-06-01Epub Date: 2026-02-02DOI: 10.1016/j.optlaseng.2026.109666
Lucas Person , Théo Sentagne , Raphaël Fouque , Robin Bouclier , John-Eric Dufour , Jean-Charles Passieux , Jean-Noël Périé
Digital Image Correlation typically involves deforming a pixelated image in order to compare its grey levels with those of another image. To achieve sub-pixel accuracy, grey-level interpolation is required. However, this interpolation is non-physical and introduces biases that become particularly detrimental under finite strains. In this work, we propose an alternative photometric approach that entirely avoids interpolation, grounded in a rigorous formulation of the direct image formation problem. The inverse problem is then posed as the joint estimation of a super-resolved digital twin—representing the scene and sensor characteristics—and the displacement fields. Both are estimated by minimising a single cost function that compares all available real images to their synthetic counterparts generated through a physically based rendering model. This minimisation is performed using an efficient alternating minimisation scheme. Several two-dimensional test cases are analysed, demonstrating that the proposed method is effectively unbiased and exhibits significantly lower uncertainties than state-of-the-art DIC techniques.
{"title":"A Photometric approach to Digital Image Correlation with a Super-Resolved digital twin (SR-PhDIC)","authors":"Lucas Person , Théo Sentagne , Raphaël Fouque , Robin Bouclier , John-Eric Dufour , Jean-Charles Passieux , Jean-Noël Périé","doi":"10.1016/j.optlaseng.2026.109666","DOIUrl":"10.1016/j.optlaseng.2026.109666","url":null,"abstract":"<div><div>Digital Image Correlation typically involves deforming a pixelated image in order to compare its grey levels with those of another image. To achieve sub-pixel accuracy, grey-level interpolation is required. However, this interpolation is non-physical and introduces biases that become particularly detrimental under finite strains. In this work, we propose an alternative photometric approach that entirely avoids interpolation, grounded in a rigorous formulation of the direct image formation problem. The inverse problem is then posed as the joint estimation of a super-resolved digital twin—representing the scene and sensor characteristics—and the displacement fields. Both are estimated by minimising a single cost function that compares all available real images to their synthetic counterparts generated through a physically based rendering model. This minimisation is performed using an efficient alternating minimisation scheme. Several two-dimensional test cases are analysed, demonstrating that the proposed method is effectively unbiased and exhibits significantly lower uncertainties than state-of-the-art DIC techniques.</div></div>","PeriodicalId":49719,"journal":{"name":"Optics and Lasers in Engineering","volume":"201 ","pages":"Article 109666"},"PeriodicalIF":3.7,"publicationDate":"2026-06-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146189774","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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