Optics and Laser Technology最新文献

{"title":"Simultaneous measurement of temperature by Background-oriented Schlieren and speckle interferometry: Comparison and validation","authors":"Siyuan Fang,&nbsp;Zhongfang Gao,&nbsp;Bicheng Guo,&nbsp;Brian Sangeorzan,&nbsp;Lianxiang Yang","doi":"10.1016/j.optlastec.2024.112161","DOIUrl":"10.1016/j.optlastec.2024.112161","url":null,"abstract":"<div><div>The application of Background-oriented Schlieren (BOS) technology for measuring air flow temperatures is becoming increasingly popular due to its simplicity and practicality. However, there is still a lack of synchronous experimental measurement techniques to verify its measurement accuracy. Electronic Speckle Pattern Interferometry (ESPI), as a high-precision measurement technique, is currently being employed in the field of temperature field measurements. In this study, to verify the accuracy of BOS, an innovative optical setup was designed to achieve the synchronous measurement of temperature field by BOS and ESPI. A plate is set in the object beam path of ESPI, and the laser is irradiated on the plate to form a BOS measurement laser speckle background pattern, which forms a BOS measurement system with the camera. The two measurement systems can simultaneously capture speckle patterns before and after the hot air flow field is introduced into the optical path, enabling the calculation of air temperature. This approach avoids errors that may arise from slight variations in the flow field when comparing results from non-synchronous measurements. The quality of the laser speckle is optimized by adjusting the aperture, beam expander and laser power. The measurement accuracy, uncertainty and sensitivity of BOS are evaluated in the reconstruction of the temperature field of the hot air flow above the alcohol lamp flame. The results show that the temperature field measured by BOS is consistent with the temperature field measured by speckle interferometry, and its measurement sensitivity is related to the flow field position and the focal length of the camera.</div></div>","PeriodicalId":19511,"journal":{"name":"Optics and Laser Technology","volume":"182 ","pages":"Article 112161"},"PeriodicalIF":4.6,"publicationDate":"2024-11-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142700493","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}

{"title":"Low current driven blue-violet light-emitting diodes based on p-GaN/i-Ga2O3/n-Ga2O3:Si structure","authors":"Wenwen Jin ,&nbsp;Xian Zhang ,&nbsp;Guojiao Xiang ,&nbsp;Zhiang Yue ,&nbsp;Enqin Zhao ,&nbsp;Shuaikang Wei ,&nbsp;Jingwen Shu ,&nbsp;Hangyu He ,&nbsp;Meibo Xin ,&nbsp;Fujing Dong ,&nbsp;Yang Zhao ,&nbsp;Hui Wang","doi":"10.1016/j.optlastec.2024.112173","DOIUrl":"10.1016/j.optlastec.2024.112173","url":null,"abstract":"<div><div>This paper reports a low current driven LED with p-GaN/i-Ga₂O₃/n-Ga₂O₃:Si structure prepared by radio frequency (RF) magnetron sputtering, the driving current of the device is only 0.02 mA. Compared with the reported drive current of the LEDs, the reduction is 100 or even 1000 times. Through the study of its electrical properties, it was found that it had excellent rectification characteristics at different ambient temperatures and the turn-on voltage was about 1.8 V. In addition, the leakage current was as low as 4.30 × 10^-8 mA. Through the electroluminescence test, it was found that the device had the function of emitting in the ultraviolet (363 nm) and visible (425 nm) region, which realized the blue-violet luminescence at room temperature. Furthermore, the device had excellent high temperature color stability and ultra-low color temperature of 1924 K. The color coordinate of the device at room temperature was (0.1905,0.0955). A detailed study was conducted on the electroluminescence mechanism of the device through its band structure, and the causes of the luminescence were analyzed through the Gaussian fitting of the EL spectrum.</div></div>","PeriodicalId":19511,"journal":{"name":"Optics and Laser Technology","volume":"182 ","pages":"Article 112173"},"PeriodicalIF":4.6,"publicationDate":"2024-11-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142700494","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}

{"title":"Process study of picosecond laser welding of soda-lime glass","authors":"Yichen Huang ,&nbsp;Zihao Zhang ,&nbsp;Xu Wang ,&nbsp;Liqun Li ,&nbsp;Lijun Yang ,&nbsp;Mingyu Li ,&nbsp;Wenbo Zhu","doi":"10.1016/j.optlastec.2024.112095","DOIUrl":"10.1016/j.optlastec.2024.112095","url":null,"abstract":"<div><div>The various excellent properties of glass make it widely used in aerospace, solar cells and other fields, and its processing methods have also attracted much attention. Ultra-fast laser has the characteristics of high peak energy density and low heat impact, which has unique advantages in welding of transparent materials such as glass. At this stage, most of the ultra-fast laser welding is carried out for the glass with optical contact, and the harsh optical contact conditions hinder the further application of glass welding technology. In this paper, an attempt is made to weld non-optical contacted soda-lime glass using high repetition frequency infrared picosecond laser. The effects of laser power, scanning times, scanning spacing, scanning direction and focus position on weld morphology and breaking strength were systematically investigated. The results show that the scanning times and scanning spacing affect the volume of glass melt on one hand, and the stress magnitude during the welding process on the other hand, which have a greater impact on the overall weld strength. Under the optimal process parameters, an effective connection can be achieved within ± 200 μm of the defocusing amount, and the weld formed has a size of 10 mm × 5 mm. A strength of 24.85 MPa is obtained when the force direction is perpendicular to the scanning direction. The mechanism of glass welding was finally revealed, providing technical guidance for the practical application of ultrafast laser welding of glass.</div></div>","PeriodicalId":19511,"journal":{"name":"Optics and Laser Technology","volume":"182 ","pages":"Article 112095"},"PeriodicalIF":4.6,"publicationDate":"2024-11-19","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142701301","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}

{"title":"Gaussian mixture model based invalid point removal for fringe projection profilometry","authors":"Huixin Song,&nbsp;Lingbao Kong,&nbsp;Qiyuan Wang","doi":"10.1016/j.optlastec.2024.112077","DOIUrl":"10.1016/j.optlastec.2024.112077","url":null,"abstract":"<div><div>In fringe projection profilometry, there inevitably exist many invalid points in the background and the occluded region that are not covered by the fringe pattern. The reconstruction result of invalid points is wrong, which seriously degrades the quality of the reconstructed point cloud and thus affects the measurement accuracy. Therefore, recognizing and removing invalid points is necessary. In this paper, an adaptive invalid point removal method based on Gaussian mixture model (GMM) is innovatively proposed for fringe projection profilometry (FPP). The proposed approach firstly calculates the modulation level using multistep phase-shifting method. Secondly, GMM is applied to model the density distribution of the modulation information and thus classify the pixels based on the modulation information. Thirdly, the classification results are further optimized using absolute phase gradient information and neighborhood information. Then the final classification results of the modulation intensity and the corresponding invalid point identification results can be obtained. A series of experimental results demonstrated that the method can accurately identify invalid points and improve the quality of point cloud reconstruction under different measurement scenarios.</div></div>","PeriodicalId":19511,"journal":{"name":"Optics and Laser Technology","volume":"182 ","pages":"Article 112077"},"PeriodicalIF":4.6,"publicationDate":"2024-11-19","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142701305","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}

{"title":"A continuous plane of polarization rotator and detector based on the liquid crystal Θ-cell","authors":"Deepak Kararwal,&nbsp;Rahul Panchal,&nbsp;Aloka Sinha","doi":"10.1016/j.optlastec.2024.112138","DOIUrl":"10.1016/j.optlastec.2024.112138","url":null,"abstract":"<div><div>Modulation of the polarization state of optical beams is crucial in advanced optical applications such as polarization microscopy, polarization rotation, and medical imaging. We demonstrate a continuous polarization rotator (PR) by utilizing the liquid crystals (LC) in Θ-cell configuration comprising of circular and parallel alignment of LC on two aligning glass substrates. A rotation of plane of polarization (PoP) up to ∼ 160˚ is observed using Stokes polarimetry. This is further substantiated by the mathematical analysis using Mueller matrix formalism. Further, the device is demonstrated as a PoP detector with high precision detection angle. The PoP is analyzed through single-shot imaging of the intensity distribution of transmitted light through the LC Θ-cell.</div></div>","PeriodicalId":19511,"journal":{"name":"Optics and Laser Technology","volume":"182 ","pages":"Article 112138"},"PeriodicalIF":4.6,"publicationDate":"2024-11-19","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142701300","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}

{"title":"Improved surface quality components enabled by dual-laser additive/subtractive hybrid manufacturing process: Thermal behavior and ablation mechanisms","authors":"Donghua Dai ,&nbsp;Zhiheng Xia ,&nbsp;Yuhang Long ,&nbsp;Han Zhang ,&nbsp;Jianye Liu ,&nbsp;Zhenghua Huang ,&nbsp;Keyu Shi","doi":"10.1016/j.optlastec.2024.112147","DOIUrl":"10.1016/j.optlastec.2024.112147","url":null,"abstract":"<div><div>A high roughness of the laser powder bed fusion (LPBF) process has been one of the most concerned issues in the integrated fabrication of complicated metal parts. In this research, a dual (continuous and ultrafast) laser additive-subtractive hybrid manufacturing (LASHM) process is introduced to improve the surface quality of the LPBF-processed components. Effects of the laser subtractive times and the feed rates on the side surface morphology of the LASHM-processed AISI 316L components were studied. Meanwhile, the VOF transient physical model of LPBF and double temperature physical model of LASHM were established to investigate the individual thermal behaviors and the material melting-ablation mechanisms. For the LPBF process, the operating temperature of the molten pool bottom was firstly stable in 300 K (&lt; 25 ms), then increased to 630 K (25 ms-35 ms) and finally exponentially increased to 3000 K (&gt;35 ms), implying the delayed thermal effect. Meanwhile, the operating temperature of the top region was linearly increased to 2050 K. While for the ultrafast laser subtractive process, the operating temperature of the top region was remained at ∼ 300 K with the temperature rapid increase to 2900 K below 10⁴ ps in the bottom region, leading to the direct material ablation and maintaining the LPBF-processed microstructure. At the laser subtractive times equal to four with the sequence feed rates of 10 μm, 10 μm, 8 μm and 6 μm, the surface roughness Sa and the maximum surface height difference Sz were considerably reduced from 10.774 μm and 73.387 μm to 1.933 μm and 18.151 μm.</div></div>","PeriodicalId":19511,"journal":{"name":"Optics and Laser Technology","volume":"182 ","pages":"Article 112147"},"PeriodicalIF":4.6,"publicationDate":"2024-11-19","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142701306","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}

{"title":"Microstructures and mechanical properties of pure copper manufactured by high-strength laser powder bed fusion","authors":"Yi Wei ,&nbsp;Genyu Chen ,&nbsp;Zhikang Xiao ,&nbsp;Yi Zhang ,&nbsp;Yunlong Zhou ,&nbsp;Xufei Liu ,&nbsp;Wei Li ,&nbsp;Jianbo Xu","doi":"10.1016/j.optlastec.2024.112134","DOIUrl":"10.1016/j.optlastec.2024.112134","url":null,"abstract":"<div><div>Pure copper is widely used in motor windings, heat exchangers and aerospace engines because of its high electrical and thermal conductivity. High-strength laser powder bed fusion (HS-LPBF) not only allows rapid production of components with complex geometry and high spatial resolution, but also offers various advantages such as small focal spot diameter, fine powder, and small layer thickness, providing advantages for forming complex structural parts in fields such as engines and heat exchangers. A single factor single layer experiment was performed by varying the hatch spacing (H), and the range of hatch spacing was determined according to the overlap rate. The degree of influence of process parameters on the relative density of pure copper specimens was analyzed using an orthogonal experiment, and a comparative study of the phase composition, microstructure and mechanical properties of pure copper specimens was carried out by varying the laser power. The characteristics of pure copper formed by HS-LPBF were analyzed. In addition, the effect of heat treatment on the microstructure and mechanical properties of pure copper specimens was investigated, and the fracture morphology of the specimens was observed comparatively. The results show that the HS-LPBF technique can effectively increase the energy density and improve the specific surface area of the powder and the laser absorptivity due to its small focal spot diameter, fine powder and layer thickness, thus reducing the minimum energy required to melt pure copper powder. The optimum process parameters were obtained by orthogonal experiment with a relative density of 98.1 % of the specimen. The highest hardness, ultimate tensile strength and elongation were obtained at a laser power of 260 W with 84 HV, 320 MPa and 17.8 %, respectively. This ultimate tensile strength is 18 % higher than the highest ultimate tensile strength that has been reported so far. In addition, the average grain size of the optimal specimens was 3.6 µm. Mechanical properties such as hardness, tensile strength and elongation of pure copper parts can be significantly improved by precisely controlling the process parameters, in particular laser power and hatch spacing.</div></div>","PeriodicalId":19511,"journal":{"name":"Optics and Laser Technology","volume":"182 ","pages":"Article 112134"},"PeriodicalIF":4.6,"publicationDate":"2024-11-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142701371","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}

{"title":"Rapid optimization of iron-based alloy laser cladding process based on orthogonal experiment and machine learning for Q345","authors":"Yi Zhang ,&nbsp;Peikang Bai ,&nbsp;Zhonghua Li ,&nbsp;Jie Zhang","doi":"10.1016/j.optlastec.2024.112086","DOIUrl":"10.1016/j.optlastec.2024.112086","url":null,"abstract":"<div><div>The properties of laser cladding coatings are closely correlated with process parameters. The laser power (P), scanning speed (V_S), and powder feeding rate(V_F) were optimized to enhance the comprehensive properties of laser cladding iron-based alloy single coating on Q345, with a focus on achieving targets such as dilution rate (η), aspect ratio (W/H), and hardness (H_D) of single coating. Firstly, the impact of process parameters on coating properties were analyzed through orthogonal experiments. Subsequently, prediction models between process parameters and coating properties were established by using back propagation neural network(BPNN), which optimized by particle swarm optimization(PSO) and Genetic Algorithm(GA). Finally, non-dominated sorting genetic algorithm II(NSGA-II) was employed to optimize the process parameters, and the optimized results were verified and analyzed. The findings indicate that laser power is the primary factor influencing dilution rate and hardness, while powder feeding rate primarily affects aspect ratio. The optimized process parameters include a laser power of 934 W, scanning speed of 352 mm/min, powder feeding rate of 0.64r/min, corresponding aspect ratio of 3.06, hardness of 613HV, dilution rate of 0.33. There were no obvious defects in the coating and the coating hardness was three times higher than that of the substrate. The optimization results of orthogonal experiments are constrained by the process range, fortunately, the utilization of machine learning optimization methods can effectively address these limitations and avoid the re-experiment due to improper settings in orthogonal experiments. It offers a rapid and efficient method for optimizing laser cladding process parameters.</div></div>","PeriodicalId":19511,"journal":{"name":"Optics and Laser Technology","volume":"182 ","pages":"Article 112086"},"PeriodicalIF":4.6,"publicationDate":"2024-11-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142701299","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}

{"title":"Enhanced three-channel dual-polarization silicon photonic balanced receiver for long-range FMCW laser ranging systems","authors":"Jing Wang ,&nbsp;Lin Zhu ,&nbsp;Ben Niu ,&nbsp;Yan Zuo ,&nbsp;De Zhou ,&nbsp;Rui Zhu ,&nbsp;Hongsong Xu ,&nbsp;Hao Wang ,&nbsp;Wenjie Zhu ,&nbsp;Xiong Jiang ,&nbsp;Qifeng Liu ,&nbsp;Dechuan Zhang","doi":"10.1016/j.optlastec.2024.112131","DOIUrl":"10.1016/j.optlastec.2024.112131","url":null,"abstract":"<div><div>We present an improved three-channel dual-polarization silicon photonic balanced receiver specifically designed for frequency-modulated continuous-wave (FMCW) ranging systems. By leveraging silicon photonics technology, we have integrated previously discrete functional devices onto a single chip, significantly reducing system volume and enhancing integration. To address the limitations of existing multi-channel balanced receivers, we performed a systematic analysis and optimization of the receiver’s components. Our optimizations included enhancing photodetector responsivity, minimizing dark current, refining layout and wire bonding, optimizing packaging coupling processes, and improving the bandwidth and noise characteristics of the receiving link. As a result, we developed a germanium-silicon photodetector with a high responsivity of ∼ 1.09 A/W, minimal dark current of ∼ 4 nA, and bandwidth of 28 GHz. Furthermore, we realized a 3-channel dual-polarization balanced receiver chip using 130 nm CMOS technology, achieving low loss and crosstalk through layout optimization and effective packaging. The receiver was validated through an FMCW ranging system setup, demonstrating a ranging capacity exceeding 180 m across all three channels, outperforming previous works. Our receiver satisfies the potential demands of long-range and high-resolution FMCW ranging, particularly relevant for automotive LiDAR applications.</div></div>","PeriodicalId":19511,"journal":{"name":"Optics and Laser Technology","volume":"182 ","pages":"Article 112131"},"PeriodicalIF":4.6,"publicationDate":"2024-11-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142701370","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}

{"title":"Decoupled measurement of silicon-based film and substrate thickness by hybrid reflectance spectroscopy","authors":"Bai Chengpei ,&nbsp;Sun Xinlei ,&nbsp;Liu Zhaoran,&nbsp;Niu Baoxin,&nbsp;Wang Zizheng,&nbsp;Yao Chengyuan,&nbsp;Shen Wanfu,&nbsp;Hu Chunguang","doi":"10.1016/j.optlastec.2024.112143","DOIUrl":"10.1016/j.optlastec.2024.112143","url":null,"abstract":"<div><div>Semiconductor manufacturing requires accurate measurement of film thickness, which significantly impacts the performance and reliability of device based on multilayer film structures. In this study, to simultaneously analyze multilayer films with significant thickness differences, a hybrid reflectance spectroscopy was proposed by combining differential reflectance spectroscopy (DRS) for thin films and reflectance spectroscopy (RS) for thick substrate. By integrating visible and near-infrared light, a comprehensive system is developed with microscopic imaging, DRS, and RS techniques. Furthermore, a practical algorithm was proposed to obtain the thickness differences of multilayer structure like Silicon-on-Insulator (SOI), with thickness of layers ranging from nanometers to micrometers and substrate thickness at hundreds of micrometers. The ability of wide range measurement and repeatability was verified by experiment conducted on SiO₂/Si samples, with thickness compared to nominal thickness by commercial ellipsometer across a range of 12 nm to 500 nm. The decouple of multilayer thickness was validated by experiment conducted on SOI, comparing to nominal thickness by scanning electron microscope (SEM).</div></div>","PeriodicalId":19511,"journal":{"name":"Optics and Laser Technology","volume":"182 ","pages":"Article 112143"},"PeriodicalIF":4.6,"publicationDate":"2024-11-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142701372","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}