Oscillating laser was adopted for wire arc additive manufacturing of high-strength aluminum alloy to solve the problems of low forming accuracy and unsatisfactory performances. The effects of laser power on the forming accuracy, microstructure, and mechanical properties of deposited thin-walls were mainly investigated. The results showed that increasing laser power from 1.5 to 2.5 kW improved the flatness of side-wall, and removed the forming defects such as humps, uneven height and overflow. The porosity was decreased from 2.42 % to 1.79 %, and the forming accuracy was increased by 38 %. Moreover, the average grain size of deposited microstructure was reduced by 14 % from 48.55 to 41.67 μm. Owing to these improvements, both the UTS and elongation of deposited thin-wall were improved by 10.1 % and 20.2 %, respectively. The optimized laser oscillation promoted the fast escape of bubbles in molten pool, and also formed stirring effects to transform columnar grains to refined equiaxed grains, thereby improving the mechanical properties of depositions.
{"title":"Effect of laser power on microstructure and mechanical properties of oscillating laser-arc hybrid additive manufactured high-strength aluminum alloy","authors":"Xiaohan Guo, Yunfei Meng, Qianxi Yu, Jianeng Xu, Xu Wu, Hui Chen","doi":"10.1016/j.optlastec.2025.112800","DOIUrl":"10.1016/j.optlastec.2025.112800","url":null,"abstract":"<div><div>Oscillating laser was adopted for wire arc additive manufacturing of high-strength aluminum alloy to solve the problems of low forming accuracy and unsatisfactory performances. The effects of laser power on the forming accuracy, microstructure, and mechanical properties of deposited thin-walls were mainly investigated. The results showed that increasing laser power from 1.5 to 2.5 kW improved the flatness of side-wall, and removed the forming defects such as humps, uneven height and overflow. The porosity was decreased from 2.42 % to 1.79 %, and the forming accuracy was increased by 38 %. Moreover, the average grain size of deposited microstructure was reduced by 14 % from 48.55 to 41.67 μm. Owing to these improvements, both the UTS and elongation of deposited thin-wall were improved by 10.1 % and 20.2 %, respectively. The optimized laser oscillation promoted the fast escape of bubbles in molten pool, and also formed stirring effects to transform columnar grains to refined equiaxed grains, thereby improving the mechanical properties of depositions.</div></div>","PeriodicalId":19511,"journal":{"name":"Optics and Laser Technology","volume":"187 ","pages":"Article 112800"},"PeriodicalIF":4.6,"publicationDate":"2025-03-14","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143620295","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2025-03-13DOI: 10.1016/j.optlastec.2025.112675
Marcos F.L. Alves , Jeferson F. da Silva , Jonathas M. de Oliveira , Laura M.S. dos Santos , Marcos V.D. Vermelho , Noelio O. Dantas , Andre L. Moura , Alcenísio J. Jesus-Silva , Eduardo J.S. Fonseca
We report on the efficient guiding of quantum dot (QD) luminescence in CdS-doped phosphate glasses, enabled by femtosecond laser-written waveguides. Quantum dots are well-known for their tunable optical properties and high quantum efficiency, making them ideal candidates for a wide range of photonic applications. Using ultrashort laser pulses, we fabricated buried waveguides with positive refractive index changes that successfully guided the luminescence emitted by QDs through the glass matrix. Single-track waveguides demonstrated Gaussian output beam profiles at 405 nm, while multi-track waveguides reduced optical losses and enhanced light propagation. These findings highlight the potential for QD luminescence to be effectively confined and guided, making femtosecond laser-written structures a powerful tool in developing QD-based devices. The ability to guide QD luminescence opens new pathways for applications in photonic circuits, displays, solid-state lasers, and solar energy systems, demonstrating the versatile role of QDs in integrated optical technologies.
{"title":"Efficient guiding of quantum dot luminescence in CdS-doped phosphate glasses via femtosecond laser-written waveguides","authors":"Marcos F.L. Alves , Jeferson F. da Silva , Jonathas M. de Oliveira , Laura M.S. dos Santos , Marcos V.D. Vermelho , Noelio O. Dantas , Andre L. Moura , Alcenísio J. Jesus-Silva , Eduardo J.S. Fonseca","doi":"10.1016/j.optlastec.2025.112675","DOIUrl":"10.1016/j.optlastec.2025.112675","url":null,"abstract":"<div><div>We report on the efficient guiding of quantum dot (QD) luminescence in CdS-doped phosphate glasses, enabled by femtosecond laser-written waveguides. Quantum dots are well-known for their tunable optical properties and high quantum efficiency, making them ideal candidates for a wide range of photonic applications. Using ultrashort laser pulses, we fabricated buried waveguides with positive refractive index changes that successfully guided the luminescence emitted by QDs through the glass matrix. Single-track waveguides demonstrated Gaussian output beam profiles at 405 nm, while multi-track waveguides reduced optical losses and enhanced light propagation. These findings highlight the potential for QD luminescence to be effectively confined and guided, making femtosecond laser-written structures a powerful tool in developing QD-based devices. The ability to guide QD luminescence opens new pathways for applications in photonic circuits, displays, solid-state lasers, and solar energy systems, demonstrating the versatile role of QDs in integrated optical technologies.</div></div>","PeriodicalId":19511,"journal":{"name":"Optics and Laser Technology","volume":"187 ","pages":"Article 112675"},"PeriodicalIF":4.6,"publicationDate":"2025-03-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143610646","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2025-03-13DOI: 10.1016/j.optlastec.2025.112779
Lei Chen , Longfei Yin , Xiaoqian Liang , Tiantian Liu , Yanrui Guo , Murong Li , Wenting Yu , Guohua Wu
In our research, we conducted a detailed analysis of the impact and causes of argon (Ar) as a buffer gas on the transmission characteristics of K-FADOF at the wavelenght of 767 nm and 770 nm. The experimental findings indicate that the incorporation of Ar has a profound effect on reshaping the spectral transmission of both the D1 and D2 lines. Notably, as the argon pressure rises, the sidebands of the D2 line are significantly subdued, while intriguingly, its central peak retains a transmission level of 40 %. Simultaneously, there is a general degradation in the transmission efficiency of the D1 line, which can be attributed to its formation mechanism mirroring that of the D2 line’s sidebands, making it susceptible to suppression by argon. The strategy of introducing argon to modulate the transmission spectrum not only provides valuable insights for the design of high-performance 770 nm K-FADOF but is also applicable to Na-FADOF, aiding in the design of high-performance filters that can effectively suppress mutual interference caused by the mere 0.6 nm wavelength difference between their yellow doublets.
{"title":"Investigation on the differential impact of argon on the transmission performance of the atomic Faraday filter operating in the potassium yellow doublet","authors":"Lei Chen , Longfei Yin , Xiaoqian Liang , Tiantian Liu , Yanrui Guo , Murong Li , Wenting Yu , Guohua Wu","doi":"10.1016/j.optlastec.2025.112779","DOIUrl":"10.1016/j.optlastec.2025.112779","url":null,"abstract":"<div><div>In our research, we conducted a detailed analysis of the impact and causes of argon (Ar) as a buffer gas on the transmission characteristics of K-FADOF at the wavelenght of 767 nm and 770 nm. The experimental findings indicate that the incorporation of Ar has a profound effect on reshaping the spectral transmission of both the D1 and D2 lines. Notably, as the argon pressure rises, the sidebands of the D2 line are significantly subdued, while intriguingly, its central peak retains a transmission level of 40 %. Simultaneously, there is a general degradation in the transmission efficiency of the D1 line, which can be attributed to its formation mechanism mirroring that of the D2 line’s sidebands, making it susceptible to suppression by argon. The strategy of introducing argon to modulate the transmission spectrum not only provides valuable insights for the design of high-performance 770 nm K-FADOF but is also applicable to Na-FADOF, aiding in the design of high-performance filters that can effectively suppress mutual interference caused by the mere 0.6 nm wavelength difference between their yellow doublets.</div></div>","PeriodicalId":19511,"journal":{"name":"Optics and Laser Technology","volume":"187 ","pages":"Article 112779"},"PeriodicalIF":4.6,"publicationDate":"2025-03-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143610644","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2025-03-13DOI: 10.1016/j.optlastec.2025.112802
Yufeng Wang , Wenhao Zhang , Dan Chen , Gerui Zhang , Tao Gong , Zhaofeng Liang , Anmin Yin , Yanjie Zhang , Wenxiang Ding
The multi-modal coupling of the laser generated ultrasonic waves in metallic additive manufacturing poses significant challenges for defects detection when using traditional C-scan imaging methods. This paper proposes an improved MobileViT-based intelligent method for defects detection using laser ultrasonic C-scan imaging. First, the Efficient Channel Attention is integrated into the inverted residual block to enhance the prominent features in the down-sampled feature maps. Second, a Receptive-Field Attention Convolution is introduced to dynamically assign convolutional kernel weights based on the significance of image features, enhancing the model’s capability to capture global image features. When utilizing C-scan image sequences from metal additive manufactured structures, the modified MobileViT network achieves a defect recognition accuracy of 98.31%. In addition, the proposed network also shows good classification results on the public NEU-CLS dataset, surpassing the comprehensive performance of EfficientNetB1, ShuffleNetV2, et al. This result shows that the improved MobileViT network offers a promising solution for defect detection precisely in metal additive manufacturing, which has potential for online inspection applications in the future.
{"title":"Defects detection in metallic additive manufactured structures utilizing multi-modal laser ultrasonic imaging integrated with an improved MobileViT network","authors":"Yufeng Wang , Wenhao Zhang , Dan Chen , Gerui Zhang , Tao Gong , Zhaofeng Liang , Anmin Yin , Yanjie Zhang , Wenxiang Ding","doi":"10.1016/j.optlastec.2025.112802","DOIUrl":"10.1016/j.optlastec.2025.112802","url":null,"abstract":"<div><div>The multi-modal coupling of the laser generated ultrasonic waves in metallic additive manufacturing poses significant challenges for defects detection when using traditional C-scan imaging methods. This paper proposes an improved MobileViT-based intelligent method for defects detection using laser ultrasonic C-scan imaging. First, the Efficient Channel Attention is integrated into the inverted residual block to enhance the prominent features in the down-sampled feature maps. Second, a Receptive-Field Attention Convolution is introduced to dynamically assign convolutional kernel weights based on the significance of image features, enhancing the model’s capability to capture global image features. When utilizing C-scan image sequences from metal additive manufactured structures, the modified MobileViT network achieves a defect recognition accuracy of 98.31%. In addition, the proposed network also shows good classification results on the public NEU-CLS dataset, surpassing the comprehensive performance of EfficientNetB1, ShuffleNetV2, et al. This result shows that the improved MobileViT network offers a promising solution for defect detection precisely in metal additive manufacturing, which has potential for online inspection applications in the future.</div></div>","PeriodicalId":19511,"journal":{"name":"Optics and Laser Technology","volume":"187 ","pages":"Article 112802"},"PeriodicalIF":4.6,"publicationDate":"2025-03-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143620816","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2025-03-13DOI: 10.1016/j.optlastec.2025.112791
Leshi Shu, Gang Zou, Zhaoxu Meng, Yilin Wang
The surface defect detection method of weld seam based on line-structured light has the advantages of non-contact measurement, high accuracy, and strong anti-interference capability, which has received increasing attention. How to improve the efficiency of defect detection to meet the needs of online detection in actual industry, while ensuring detection accuracy remains a challenge. This study proposed a surface defect detection method for weld seam based on Stacked Auto Encoder (SAE) model and background extraction method. In the proposed method, the raw weld contour data obtained from the structured light sensor is preprocessed to reduce the influence of environmental noise and sensor movement. Then defect detection is divided into two steps: defect recognition and defect segmentation. The former applies the SAE model to identify defective areas in the entire weld seam to avoid analyzing defect free areas and improve efficiency, while the latter uses the background extraction method to segment defects from the contour of the weld seam containing defects to reduce the complexity of defect segmentation. The proposed method has been applied to the typical defect detection of aluminum alloy samples of high-speed rail vehicle bodies, such as surface pore, arc pits, overlap, undercut, and surface collapse. The results show that the accuracy of the defect recognition model in recognizing continuous weld defects exceeds 97 %. The segmentation error of typical weld seam defects is within 0.2 mm.
{"title":"An online surface defect detection method for weld seam based on SAE model and background extraction method","authors":"Leshi Shu, Gang Zou, Zhaoxu Meng, Yilin Wang","doi":"10.1016/j.optlastec.2025.112791","DOIUrl":"10.1016/j.optlastec.2025.112791","url":null,"abstract":"<div><div>The surface defect detection method of weld seam based on line-structured light has the advantages of non-contact measurement, high accuracy, and strong anti-interference capability, which has received increasing attention. How to improve the efficiency of defect detection to meet the needs of online detection in actual industry, while ensuring detection accuracy remains a challenge. This study proposed a surface defect detection method for weld seam based on Stacked Auto Encoder (SAE) model and background extraction method. In the proposed method, the raw weld contour data obtained from the structured light sensor is preprocessed to reduce the influence of environmental noise and sensor movement. Then defect detection is divided into two steps: defect recognition and defect segmentation. The former applies the SAE model to identify defective areas in the entire weld seam to avoid analyzing defect free areas and improve efficiency, while the latter uses the background extraction method to segment defects from the contour of the weld seam containing defects to reduce the complexity of defect segmentation. The proposed method has been applied to the typical defect detection of aluminum alloy samples of high-speed rail vehicle bodies, such as surface pore, arc pits, overlap, undercut, and surface collapse. The results show that the accuracy of the defect recognition model in recognizing continuous weld defects exceeds 97 %. The segmentation error of typical weld seam defects is within 0.2 mm.</div></div>","PeriodicalId":19511,"journal":{"name":"Optics and Laser Technology","volume":"187 ","pages":"Article 112791"},"PeriodicalIF":4.6,"publicationDate":"2025-03-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143620817","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2025-03-13DOI: 10.1016/j.optlastec.2025.112790
Yang Liu , Pengfei Ouyang , Zhaoyang Zhang , Wei Xue , Yufeng Wang , Hao Zhu , Kun Xu , Jingtao Wang , Jie Cai , Jinzhong Lu
The cooling holes of the blade of aircraft engines play an important role in improving their performance. In this paper, a water-assisted laser machining method is proposed as a means of achieving high-quality manufacturing of the cooling holes. Multi-energy field simulations and extensive experiments were carried out to explore the processing effects of this new composite manufacturing technology. The mechanism of the backside water-assisted laser machining process was analyzed using finite element multi-energy field simulation. It was demonstrated that the cooling effect of the backside water flow became increasingly significant as the number of laser pulses increased. The experimental results of the backside water-assisted laser drilling for the straight and inclined circular, square and trapezoidal holes exhibited superior performance. It was demonstrated that the entrances and exits of the micro-holes prepared by the water-assisted laser drilling process exhibited increased dimensions, enhanced entrance morphology, superior quality of the hole wall, and a notable reduction in thermal defects. The interaction between the liquid and the laser enabled the secondary removal of the hole wall material, which in turn improved the quality of micro-hole.
{"title":"Multi-energy field simulation and experimental research on backside water assisted laser processing for thin-walled irregular metal micro-holes","authors":"Yang Liu , Pengfei Ouyang , Zhaoyang Zhang , Wei Xue , Yufeng Wang , Hao Zhu , Kun Xu , Jingtao Wang , Jie Cai , Jinzhong Lu","doi":"10.1016/j.optlastec.2025.112790","DOIUrl":"10.1016/j.optlastec.2025.112790","url":null,"abstract":"<div><div>The cooling holes of the blade of aircraft engines play an important role in improving their performance. In this paper, a water-assisted laser machining method is proposed as a means of achieving high-quality manufacturing of the cooling holes. Multi-energy field simulations and extensive experiments were carried out to explore the processing effects of this new composite manufacturing technology. The mechanism of the backside water-assisted laser machining process was analyzed using finite element multi-energy field simulation. It was demonstrated that the cooling effect of the backside water flow became increasingly significant as the number of laser pulses increased. The experimental results of the backside water-assisted laser drilling for the straight and inclined circular, square and trapezoidal holes exhibited superior performance. It was demonstrated that the entrances and exits of the micro-holes prepared by the water-assisted laser drilling process exhibited increased dimensions, enhanced entrance morphology, superior quality of the hole wall, and a notable reduction in thermal defects. The interaction between the liquid and the laser enabled the secondary removal of the hole wall material, which in turn improved the quality of micro-hole.</div></div>","PeriodicalId":19511,"journal":{"name":"Optics and Laser Technology","volume":"187 ","pages":"Article 112790"},"PeriodicalIF":4.6,"publicationDate":"2025-03-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143620815","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2025-03-13DOI: 10.1016/j.optlastec.2025.112756
Min Li , Xin Liu , Junbo Zhang , Ang Zhang , Hao Xian
Telescope alignment is one of the key factors to ensure the image quality and resolutions. In this paper, a wavefront sensorless method based on images using optimization algorithms is proposed. To verify the validity and universality, different kinds of telescopes are employed, and misalignments are corrected based on images with various sampling parameters. Nesterov-accelerated adaptive moment stochastic parallel gradient descent (Nadam SPGD) algorithm is adopted to search for the optimal solution in simulations. Results show that the average errors in the 80% encircled energy radius between corrected images and designed images are no larger than 0.2 pixels, satisfying the demands of image quality. Without increasing complexity of optical systems and alignment processes, the proposed method can align telescopes effectively even if images are undersampled seriously.
{"title":"Research on telescope alignment using a generic wavefront sensorless method based on images with different sampling parameters","authors":"Min Li , Xin Liu , Junbo Zhang , Ang Zhang , Hao Xian","doi":"10.1016/j.optlastec.2025.112756","DOIUrl":"10.1016/j.optlastec.2025.112756","url":null,"abstract":"<div><div>Telescope alignment is one of the key factors to ensure the image quality and resolutions. In this paper, a wavefront sensorless method based on images using optimization algorithms is proposed. To verify the validity and universality, different kinds of telescopes are employed, and misalignments are corrected based on images with various sampling parameters. Nesterov-accelerated adaptive moment stochastic parallel gradient descent (Nadam SPGD) algorithm is adopted to search for the optimal solution in simulations. Results show that the average errors in the 80% encircled energy radius between corrected images and designed images are no larger than 0.2 pixels, satisfying the demands of image quality. Without increasing complexity of optical systems and alignment processes, the proposed method can align telescopes effectively even if images are undersampled seriously.</div></div>","PeriodicalId":19511,"journal":{"name":"Optics and Laser Technology","volume":"187 ","pages":"Article 112756"},"PeriodicalIF":4.6,"publicationDate":"2025-03-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143610645","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2025-03-12DOI: 10.1016/j.optlastec.2025.112788
Lihui Xu , Guoqing Yuan
Nanosecond lasers are widely used in surface modification of materials, and research into their ablation mechanisms remains ongoing. In this study, copper was selected as the research object, and a finite element model (FEM) coupling heat transfer and fluid flow was established using the level set method. The nanosecond laser ablation process under movement was studied in detail. The effects of thermal accumulation from multi-pulse moving lasers on the morphology of ablation craters were analyzed, along with the variation patterns of crater morphology under different average powers, pulse frequencies, and scanning speeds. The results indicate that (a) the increase in average power and the decrease in pulse frequency lead to higher energy density, resulting in a smaller recast layer, a larger heat-affected zone (HAZ), deeper craters, larger crater radii, and higher crater rims. Additionally, subsequent pulses have an increasing impact on the morphology of previously formed craters, potentially leading to crater tilt defects. (b) In operating conditions (OC) 1, 2, 7, and 8, copper has already melted and vaporized by the end of the first pulse. During solidification, the crater size gradually decreases, and small rims form on both sides of the crater due to Marangoni forces and recoil pressure. The solidification process lasts 11.3 times longer than the melting process. (c) The ablation threshold of copper ranges between 12.73 and 19.10 J/cm2. A multiple linear regression fit yielded a relationship between the crater depth and energy density as well as the overlap rate: hd = -8.78 + 0.68ψ + 0.60δ, which accurately predicts crater depth. This provides a theoretical foundation for predicting the crater morphology in moving pulsed laser ablation (PLA) and optimizing laser processing parameters.
{"title":"The detailed study of surface morphology evolution in copper under moving pulsed laser ablation considering thermal-fluid-solid coupling effects","authors":"Lihui Xu , Guoqing Yuan","doi":"10.1016/j.optlastec.2025.112788","DOIUrl":"10.1016/j.optlastec.2025.112788","url":null,"abstract":"<div><div>Nanosecond lasers are widely used in surface modification of materials, and research into their ablation mechanisms remains ongoing. In this study, copper was selected as the research object, and a finite element model (FEM) coupling heat transfer and fluid flow was established using the level set method. The nanosecond laser ablation process under movement was studied in detail. The effects of thermal accumulation from multi-pulse moving lasers on the morphology of ablation craters were analyzed, along with the variation patterns of crater morphology under different average powers, pulse frequencies, and scanning speeds. The results indicate that (a) the increase in average power and the decrease in pulse frequency lead to higher energy density, resulting in a smaller recast layer, a larger heat-affected zone (HAZ), deeper craters, larger crater radii, and higher crater rims. Additionally, subsequent pulses have an increasing impact on the morphology of previously formed craters, potentially leading to crater tilt defects. (b) In operating conditions (OC) 1, 2, 7, and 8, copper has already melted and vaporized by the end of the first pulse. During solidification, the crater size gradually decreases, and small rims form on both sides of the crater due to Marangoni forces and recoil pressure. The solidification process lasts 11.3 times longer than the melting process. (c) The ablation threshold of copper ranges between 12.73 and 19.10 J/cm<sup>2</sup>. A multiple linear regression fit yielded a relationship between the crater depth and energy density as well as the overlap rate: <em>h</em><sub>d</sub> = -8.78 + 0.68<em>ψ</em> + 0.60<em>δ</em>, which accurately predicts crater depth. This provides a theoretical foundation for predicting the crater morphology in moving pulsed laser ablation (PLA) and optimizing laser processing parameters.</div></div>","PeriodicalId":19511,"journal":{"name":"Optics and Laser Technology","volume":"187 ","pages":"Article 112788"},"PeriodicalIF":4.6,"publicationDate":"2025-03-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143610643","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2025-03-12DOI: 10.1016/j.optlastec.2025.112757
Muhammad Awais , Taeil Yoon , Chi-Ok Hwang , Byeongha Lee
In optics, phase measurement techniques face challenges because phase values are confined within 2π, leading to the problem of phase unwrapping. Many methods, including deep learning-based approaches, have been proposed to address this issue. However, high noise in a wrapped phase image often causes these techniques to fail, resulting in error accumulation and high computation time. To overcome these challenges, we propose a robust and fast deep learning-based method called DenSFA-PU (Densely Connected Spatial Feature Aggregator for Phase Unwrapping), which treats this problem as a regression task. Our approach uses an encoder-decoder architecture with densely connected neural networks and a spatial feature aggregator module for noise reduction and robust feature representation. Comparative analysis using both synthetic data and real-world data obtained through digital holography demonstrates that our method outperforms existing techniques, achieving greater computational efficiency with an average unwrapping time of 29.31 ms, significantly faster than other methods. It also shows superior accuracy, with consistently good NRMSE, PSNR, and SSIM values across all cases, highlighting its robustness in handling highly noisy wrapped phase images. Additionally, its ability to operate with minimal training data makes it highly suitable for the applications requiring fast and accurate phase unwrapping with a limited data set.
{"title":"DenSFA-PU: Learning to unwrap phase in severe noisy conditions","authors":"Muhammad Awais , Taeil Yoon , Chi-Ok Hwang , Byeongha Lee","doi":"10.1016/j.optlastec.2025.112757","DOIUrl":"10.1016/j.optlastec.2025.112757","url":null,"abstract":"<div><div>In optics, phase measurement techniques face challenges because phase values are confined within 2π, leading to the problem of phase unwrapping. Many methods, including deep learning-based approaches, have been proposed to address this issue. However, high noise in a wrapped phase image often causes these techniques to fail, resulting in error accumulation and high computation time. To overcome these challenges, we propose a robust and fast deep learning-based method called DenSFA-PU (<strong>Den</strong>sely Connected <strong>S</strong>patial <strong>F</strong>eature <strong>A</strong>ggregator for <strong>P</strong>hase <strong>U</strong>nwrapping), which treats this problem as a regression task. Our approach uses an encoder-decoder architecture with densely connected neural networks and a spatial feature aggregator module for noise reduction and robust feature representation. Comparative analysis using both synthetic data and real-world data obtained through digital holography demonstrates that our method outperforms existing techniques, achieving greater computational efficiency with an average unwrapping time of 29.31 ms, significantly faster than other methods. It also shows superior accuracy, with consistently good NRMSE, PSNR, and SSIM values across all cases, highlighting its robustness in handling highly noisy wrapped phase images. Additionally, its ability to operate with minimal training data makes it highly suitable for the applications requiring fast and accurate phase unwrapping with a limited data set.</div></div>","PeriodicalId":19511,"journal":{"name":"Optics and Laser Technology","volume":"187 ","pages":"Article 112757"},"PeriodicalIF":4.6,"publicationDate":"2025-03-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143601815","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
This work explores application of NiTi shape memory alloy (SMA) thin film composite structure in a parallel manipulator assembly for laser beam steering. A thin and lightweight NiTi SMA based mirror fabricated by thermal evaporation was manipulated with the help of four bimorph actuators assembled in a Stewart platform arrangement. By utilizing ArUco-based markers and computer vision techniques, the live position of the mirror was monitored. The program analyzed the position and tilt of three ArUco markers on the mirror to determine the tilt of the mirror on actuation. The maximum tilt of the mirror achieved was 28.76° with respect to x direction for an 8 V supply and 0.25 Hz frequency. Moreover, the position of the laser beam reflected from the micromirror was also studied. The maximum deflection achieved for the reflected laser beam was 1.01°±0.18° in x-direction and 0.42°±0.05° in z-direction.
{"title":"Realization of SMA bimorph based composite mirror and actuator in a Stewart platform arrangement for beam steering application","authors":"Kaushal Gangwar, Srijan Parashar, Palani Iyamperumal Anand","doi":"10.1016/j.optlastec.2025.112765","DOIUrl":"10.1016/j.optlastec.2025.112765","url":null,"abstract":"<div><div>This work explores application of NiTi shape memory alloy (SMA) thin film composite structure in a parallel manipulator assembly for laser beam steering. A thin and lightweight NiTi SMA based mirror fabricated by thermal evaporation was manipulated with the help of four bimorph actuators assembled in a Stewart platform arrangement. By utilizing ArUco-based markers and computer vision techniques, the live position of the mirror was monitored. The program analyzed the position and tilt of three ArUco markers on the mirror to determine the tilt of the mirror on actuation. The maximum tilt of the mirror achieved was 28.76° with respect to x direction for an 8 V supply and 0.25 Hz frequency. Moreover, the position of the laser beam reflected from the micromirror was also studied. The maximum deflection achieved for the reflected laser beam was 1.01°±0.18° in x-direction and 0.42°±0.05° in z-direction.</div></div>","PeriodicalId":19511,"journal":{"name":"Optics and Laser Technology","volume":"187 ","pages":"Article 112765"},"PeriodicalIF":4.6,"publicationDate":"2025-03-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143601816","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
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