Pub Date : 2025-04-25DOI: 10.1016/j.optlaseng.2025.109035
Fengjia Gao , Fei Gao , Li Wang , Yuehui Song , Dengxin Hua , Griša Močnik , Samo Stanič
Multi-longitudinal-mode (MLM) high-spectral-resolution lidar is a new concept of incoherent Doppler wind lidar (IDWL), which can avoid the complex techniques of seed injection as well as the high requirement of frequency stabilization and frequency locking. To achieve high-precision atmospheric wind measurement, an optimized design is performed for the MLM IDWL, which utilizes a free-running MLM laser as the excitation light source and a quadri-channel Mach-Zehnder interferometer (QMZI) as the spectral discriminator. Based on the partial coherence theory of quasi-monochromatic light interference, the data inversion algorithms for MLM IDWL are simplified, and the performance evaluation parameters for MLM IDWL are analyzed. Furthermore, using the control variable method, the key parameters of MLM IDWL are optimized by discussing its performance evaluation parameters in the condition of aerosol Mie scattering or molecular Rayleigh scattering, respectively. The simulation experiments of wind measurement with the optimal key parameters prove that the MLM IDWL can realize the atmospheric wind measurement with an accuracy of 0.3 m/s in the low-altitude environments using aerosol Mie scattering echo signals and with an accuracy of 3.0 m/s in the high-altitude environments using molecular Rayleigh scattering echo signals.
{"title":"Optimization of multi-longitudinal-mode incoherent doppler wind lidar with quadri-channel mach–zehnder interferometer","authors":"Fengjia Gao , Fei Gao , Li Wang , Yuehui Song , Dengxin Hua , Griša Močnik , Samo Stanič","doi":"10.1016/j.optlaseng.2025.109035","DOIUrl":"10.1016/j.optlaseng.2025.109035","url":null,"abstract":"<div><div>Multi-longitudinal-mode (MLM) high-spectral-resolution lidar is a new concept of incoherent Doppler wind lidar (IDWL), which can avoid the complex techniques of seed injection as well as the high requirement of frequency stabilization and frequency locking. To achieve high-precision atmospheric wind measurement, an optimized design is performed for the MLM IDWL, which utilizes a free-running MLM laser as the excitation light source and a quadri-channel Mach-Zehnder interferometer (QMZI) as the spectral discriminator. Based on the partial coherence theory of quasi-monochromatic light interference, the data inversion algorithms for MLM IDWL are simplified, and the performance evaluation parameters for MLM IDWL are analyzed. Furthermore, using the control variable method, the key parameters of MLM IDWL are optimized by discussing its performance evaluation parameters in the condition of aerosol Mie scattering or molecular Rayleigh scattering, respectively. The simulation experiments of wind measurement with the optimal key parameters prove that the MLM IDWL can realize the atmospheric wind measurement with an accuracy of 0.3 m/s in the low-altitude environments using aerosol Mie scattering echo signals and with an accuracy of 3.0 m/s in the high-altitude environments using molecular Rayleigh scattering echo signals.</div></div>","PeriodicalId":49719,"journal":{"name":"Optics and Lasers in Engineering","volume":"192 ","pages":"Article 109035"},"PeriodicalIF":3.5,"publicationDate":"2025-04-25","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143870533","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}
A multi-wavelength underwater wireless optical communication (UWOC) was experimented and studied. The multi-wavelength 450 nm, 518 nm, and 655 nm laser source was used to transmit information in the underwater-air medium up to 17-meter. The data rate used in this study was up to 2.5 Gbps. The optical loss in the 450 nm, 518 nm, and 655 nm in water per meter were 0.55 dB, 0.56 dB, and 0.69 dB, respectively. Several environmental effects such as turbulence and temperature changes were investigated. The bit error rate (BER) value of red, green, and blue-laser can achieve up to , , , respectively under turbulence influence. The laser beam is diverged due to wave and floating bubbles under turbulence influences, especially using a 655 nm red-laser diode. A temperature change did not significantly change the BER value as the turbulence did. The multi-wavelength 450 nm, 518 nm, and 655 nm laser source can achieve bit error rate (BER) under the forward error correction (FEC) limit. This study can further improve the researcher design of their UWOC system for various applications.
{"title":"Performance evaluation of multi-wavelength visible light underwater optical communication","authors":"Shofuro Afifah , Jun-Kai Wei , Lina Marlina , Shien-Kuei Liaw , Pei-Jun Lee , Chien-Hung Yeh","doi":"10.1016/j.optlaseng.2025.109026","DOIUrl":"10.1016/j.optlaseng.2025.109026","url":null,"abstract":"<div><div>A multi-wavelength underwater wireless optical communication (UWOC) was experimented and studied. The multi-wavelength 450 nm, 518 nm, and 655 nm laser source was used to transmit information in the underwater-air medium up to 17-meter. The data rate used in this study was up to 2.5 Gbps. The optical loss in the 450 nm, 518 nm, and 655 nm in water per meter were 0.55 dB, 0.56 dB, and 0.69 dB, respectively. Several environmental effects such as turbulence and temperature changes were investigated. The bit error rate (BER) value of red, green, and blue-laser can achieve up to <span><math><mrow><mn>2.1</mn><mspace></mspace><mo>×</mo><msup><mrow><mn>10</mn></mrow><mrow><mo>−</mo><mn>5</mn></mrow></msup></mrow></math></span>, <span><math><mrow><mn>3.1</mn><mspace></mspace><mo>×</mo><msup><mrow><mn>10</mn></mrow><mrow><mo>−</mo><mn>8</mn></mrow></msup></mrow></math></span>, <span><math><mrow><mn>1.7</mn><mspace></mspace><mo>×</mo><msup><mrow><mn>10</mn></mrow><mrow><mo>−</mo><mn>12</mn></mrow></msup></mrow></math></span>, respectively under turbulence influence. The laser beam is diverged due to wave and floating bubbles under turbulence influences, especially using a 655 nm red-laser diode. A temperature change did not significantly change the BER value as the turbulence did. The multi-wavelength 450 nm, 518 nm, and 655 nm laser source can achieve bit error rate (BER) under the forward error correction (FEC) limit. This study can further improve the researcher design of their UWOC system for various applications.</div></div>","PeriodicalId":49719,"journal":{"name":"Optics and Lasers in Engineering","volume":"192 ","pages":"Article 109026"},"PeriodicalIF":3.5,"publicationDate":"2025-04-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143864161","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 : 2025-04-24DOI: 10.1016/j.optlaseng.2025.109032
Mingyang Chen , Jiyue Wang , Mengge Liu , Ziqin Xu , Hao Liu , Mingliang Xu
Passive non-line-of-sight (NLOS) imaging extends the observer's perceptual range, offering promising applications in fields such as autonomous driving and emergency rescue. However, mainstream passive NLOS imaging methods are generally limited to distances of less than 6 meters and often rely on a single simulated light transmission matrix, overlooking brightness and reflection characteristics. To overcome these limitations, we employ an infrared camera to capture relayed signals from long distances and introduce the NLOS Pedestrian Imaging Algorithm based on Light Transport Matrix Decomposition (NLOS-LTMD). This innovative algorithm simulates the light transport matrix in two parts: an illumination transport matrix for reconstructing brightness and a reflection transport matrix for enhancing contours. In addition, we propose an Illumination-Oriented Transformer (IO-Transformer) that utilizes threshold segmentation to identify the most informative regions based on the intensity of illumination information addressing the issue of introducing noise and low-SNR regions during contextual modeling, which can degrade imaging quality. Quantitative and qualitative experiments demonstrate that NLOS-LTMD markedly surpasses existing methods in both robustness and reconstruction quality.
{"title":"Passive non-line-of-sight pedestrian imaging based on light transport matrix decomposition","authors":"Mingyang Chen , Jiyue Wang , Mengge Liu , Ziqin Xu , Hao Liu , Mingliang Xu","doi":"10.1016/j.optlaseng.2025.109032","DOIUrl":"10.1016/j.optlaseng.2025.109032","url":null,"abstract":"<div><div>Passive non-line-of-sight (NLOS) imaging extends the observer's perceptual range, offering promising applications in fields such as autonomous driving and emergency rescue. However, mainstream passive NLOS imaging methods are generally limited to distances of less than 6 meters and often rely on a single simulated light transmission matrix, overlooking brightness and reflection characteristics. To overcome these limitations, we employ an infrared camera to capture relayed signals from long distances and introduce the NLOS Pedestrian Imaging Algorithm based on Light Transport Matrix Decomposition (NLOS-LTMD). This innovative algorithm simulates the light transport matrix in two parts: an illumination transport matrix for reconstructing brightness and a reflection transport matrix for enhancing contours. In addition, we propose an Illumination-Oriented Transformer (IO-Transformer) that utilizes threshold segmentation to identify the most informative regions based on the intensity of illumination information addressing the issue of introducing noise and low-SNR regions during contextual modeling, which can degrade imaging quality. Quantitative and qualitative experiments demonstrate that NLOS-LTMD markedly surpasses existing methods in both robustness and reconstruction quality.</div></div>","PeriodicalId":49719,"journal":{"name":"Optics and Lasers in Engineering","volume":"192 ","pages":"Article 109032"},"PeriodicalIF":3.5,"publicationDate":"2025-04-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143870532","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 : 2025-04-23DOI: 10.1016/j.optlaseng.2025.109018
Deepika Tyagi , Vijay Laxmi , Barkathulla Asrafali , Abida Parveen , Mi Lin , Qiong Wang , Keyu Tao , Qiang Liu , Suling Shen , Zhengbiao Ouyang
We present a method of terahertz (THz) wave generation in the complete THz band that harnesses resonance modes within high-quality-factor photonic-crystal resonators. In the proposed method, the input infrared “single-frequency” wave and the resonance mode induced efficiently in the resonator generate a beat note of THz frequency, and the beat note is converted to an independent THz radiation wave with the help of an amplitude demodulator, which provides high power-conversion efficiency (PCE). The theoretical PCE is a 22.93 % half-wave-rectification amplitude demodulator without considering the insertion loss. Through simulations, we demonstrate the feasibility of our approach of inducing a resonance mode from a conventional “single-frequency” wave and using the induced resonance mode to beat with the input source wave with PCE of 24.03 % in agreement with the theoretical PCE value by half-wave-rectification demodulation. Such a high PCE can be obtained only at a certain frequency. The mechanism of the proposed method is further demonstrated experimentally in the microwave band. The proposed method is a general method that can be applied to frequency conversion of all kinds of waves, showcasing its potential across various applications in electronics, optics, acoustics, and beyond. We expect to overcome many future challenges in terahertz technology because of its high efficiency and miniaturization. Furthermore, our findings pave the way for efficient frequency manipulation with broad implications in signal processing, detection, and communication systems.
{"title":"Resonance-mode-induced beating effect for THz wave generation and principal demonstration","authors":"Deepika Tyagi , Vijay Laxmi , Barkathulla Asrafali , Abida Parveen , Mi Lin , Qiong Wang , Keyu Tao , Qiang Liu , Suling Shen , Zhengbiao Ouyang","doi":"10.1016/j.optlaseng.2025.109018","DOIUrl":"10.1016/j.optlaseng.2025.109018","url":null,"abstract":"<div><div>We present a method of terahertz (THz) wave generation in the complete THz band that harnesses resonance modes within high-quality-factor photonic-crystal resonators. In the proposed method, the input infrared “single-frequency” wave and the resonance mode induced efficiently in the resonator generate a beat note of THz frequency, and the beat note is converted to an independent THz radiation wave with the help of an amplitude demodulator, which provides high power-conversion efficiency (PCE). The theoretical PCE is a 22.93 % half-wave-rectification amplitude demodulator without considering the insertion loss. Through simulations, we demonstrate the feasibility of our approach of inducing a resonance mode from a conventional “single-frequency” wave and using the induced resonance mode to beat with the input source wave with PCE of 24.03 % in agreement with the theoretical PCE value by half-wave-rectification demodulation. Such a high PCE can be obtained only at a certain frequency. The mechanism of the proposed method is further demonstrated experimentally in the microwave band. The proposed method is a general method that can be applied to frequency conversion of all kinds of waves, showcasing its potential across various applications in electronics, optics, acoustics, and beyond. We expect to overcome many future challenges in terahertz technology because of its high efficiency and miniaturization. Furthermore, our findings pave the way for efficient frequency manipulation with broad implications in signal processing, detection, and communication systems.</div></div>","PeriodicalId":49719,"journal":{"name":"Optics and Lasers in Engineering","volume":"192 ","pages":"Article 109018"},"PeriodicalIF":3.5,"publicationDate":"2025-04-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143864159","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}
The depth of field is of significant importance in a multitude of imaging systems. It is difficult to balance imaging efficiency and quality. Here, we propose a real-time extended depth of field imaging system based on a liquid lens and Deblur-Unet for automated optical inspection. This method includes calibration, training and real time imaging. In the calibration setup, the liquid lens obtains both focus stack images and a focus scanning image in the same work distance range, and a fused extended depth of field image can be obtained by calculating the sharpness of the focus stack images. In the training setup, the fused extended depth of field image and the focus scanning image will be used to train a deconvolution and denoise Deblur-Unet. In the real time imaging setup, each frame of the focus scanning image obtained by the liquid lens imaging system is processed by the trained Deblur-Unet, and the corresponding extended depth of field image can be obtained. By using the proposed system, we extend the depth of field by >10 times for imaging in online Li-ion battery pole piece flip inspection. The system achieves a frame-rate of up to 50 Hz for 5MP or 20 Hz for 12MP mono images with an RTX 4060 GPU. Furthermore, the concise architecture of the proposed system has the potential to be used in 100MP high resolution and extend depth of field imaging with only one frame sampling, such as in screen inspection or microscopic biological imaging.
{"title":"Real-time extend depth of field imaging based on liquid lens and deblur-unet in automated optical inspection","authors":"Ping Jiang , Ting-Ting Chen , Wen Chen , Si-Yuan Wang","doi":"10.1016/j.optlaseng.2025.109022","DOIUrl":"10.1016/j.optlaseng.2025.109022","url":null,"abstract":"<div><div>The depth of field is of significant importance in a multitude of imaging systems. It is difficult to balance imaging efficiency and quality. Here, we propose a real-time extended depth of field imaging system based on a liquid lens and Deblur-Unet for automated optical inspection. This method includes calibration, training and real time imaging. In the calibration setup, the liquid lens obtains both focus stack images and a focus scanning image in the same work distance range, and a fused extended depth of field image can be obtained by calculating the sharpness of the focus stack images. In the training setup, the fused extended depth of field image and the focus scanning image will be used to train a deconvolution and denoise Deblur-Unet. In the real time imaging setup, each frame of the focus scanning image obtained by the liquid lens imaging system is processed by the trained Deblur-Unet, and the corresponding extended depth of field image can be obtained. By using the proposed system, we extend the depth of field by >10 times for imaging in online Li-ion battery pole piece flip inspection. The system achieves a frame-rate of up to 50 Hz for 5MP or 20 Hz for 12MP mono images with an RTX 4060 GPU. Furthermore, the concise architecture of the proposed system has the potential to be used in 100MP high resolution and extend depth of field imaging with only one frame sampling, such as in screen inspection or microscopic biological imaging.</div></div>","PeriodicalId":49719,"journal":{"name":"Optics and Lasers in Engineering","volume":"192 ","pages":"Article 109022"},"PeriodicalIF":3.5,"publicationDate":"2025-04-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143864162","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 : 2025-04-23DOI: 10.1016/j.optlaseng.2025.109033
Jian Liu , Han Su , Linghui Kong , Dongni Yang , Nan Lu , Yao Yu , Yuqian Zhao , Yi Wang , Zhenhe Ma
In the study of age-related macular degeneration (AMD), optical coherence tomography OCT has proven invaluable in identifying biomarkers that assess disease progression. However, Optical coherence tomography (OCT) signals are easily affected by light intensity, which has led to criticism in clinical applications. Optical attenuation coefficient (OAC) provides local tissue properties without the influences of the OCT system and accumulated light attenuation, which is useful for quantifying pathological changes by enhancing the differentiation between diseased and normal tissues. Previous methods of OAC for retinal imaging have not considered the influence of the backscattering fraction, which varies across different tissues. In this paper, we proposed a priori segmentation mediated local depth-resolved (LDR) algorithm to improve the accuracy and stability of retinal pigment epithelium (RPE) layer OAC calculations. The LDR algorithm utilizes a new method for estimating residual light intensity, which replaces the conventional approaches of accumulating all residual signals or using numerical fitting methods. This improvement enables the LDR algorithm to perform OAC conversion at any depth range in OCT images (including RPE), regardless of whether the light energy is completely attenuated. When there are drusen between the RPE and BM that are difficult to segment precisely, we use a backscattering compensation method to make the RPE and drusen have the same backscattering coefficient, and then use the LDR algorithm to calculate the OAC of the RPE layer. The algorithm was evaluated using phantoms, healthy subjects, and patients with early atrophic AMD, demonstrating its reliability and practicality.
{"title":"A priori segmentation mediated local depth-resolved optical attenuation coefficient mapping of RPE complex for the investigation of age-related macular degeneration","authors":"Jian Liu , Han Su , Linghui Kong , Dongni Yang , Nan Lu , Yao Yu , Yuqian Zhao , Yi Wang , Zhenhe Ma","doi":"10.1016/j.optlaseng.2025.109033","DOIUrl":"10.1016/j.optlaseng.2025.109033","url":null,"abstract":"<div><div>In the study of age-related macular degeneration (AMD), optical coherence tomography OCT has proven invaluable in identifying biomarkers that assess disease progression. However, Optical coherence tomography (OCT) signals are easily affected by light intensity, which has led to criticism in clinical applications. Optical attenuation coefficient (OAC) provides local tissue properties without the influences of the OCT system and accumulated light attenuation, which is useful for quantifying pathological changes by enhancing the differentiation between diseased and normal tissues. Previous methods of OAC for retinal imaging have not considered the influence of the backscattering fraction, which varies across different tissues. In this paper, we proposed a priori segmentation mediated local depth-resolved (LDR) algorithm to improve the accuracy and stability of retinal pigment epithelium (RPE) layer OAC calculations. The LDR algorithm utilizes a new method for estimating residual light intensity, which replaces the conventional approaches of accumulating all residual signals or using numerical fitting methods. This improvement enables the LDR algorithm to perform OAC conversion at any depth range in OCT images (including RPE), regardless of whether the light energy is completely attenuated. When there are drusen between the RPE and BM that are difficult to segment precisely, we use a backscattering compensation method to make the RPE and drusen have the same backscattering coefficient, and then use the LDR algorithm to calculate the OAC of the RPE layer. The algorithm was evaluated using phantoms, healthy subjects, and patients with early atrophic AMD, demonstrating its reliability and practicality.</div></div>","PeriodicalId":49719,"journal":{"name":"Optics and Lasers in Engineering","volume":"192 ","pages":"Article 109033"},"PeriodicalIF":3.5,"publicationDate":"2025-04-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143864160","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 : 2025-04-22DOI: 10.1016/j.optlaseng.2025.109030
Zhao Chen , Gaoliang Peng , Wei Zhang , Hongzhao Lin , Hang Li , Zhixiong Li
The rotating double-prism system, an emerging beam steering mechanism, achieves optical axis deflection through rotational modulation of two prisms, enabling high-precision angular positioning in free space. Due to the structural configuration of the two prisms arranged in series, the target tracking based on image feedback has strong nonlinear characteristics and coupling within the rotating double prism system. Consequently, the two prisms must be controlled in coordination to effectively deflect the reflected light. This paper introduces an innovative approach to adjusting the boresight by employing virtual axis angular deviation, grounded in the inverse ray tracing method. This method effectively separates the virtual pointing axis from the target visual axis. In contrast to traditional methods that rely only on the equivalent approximate information of image deviation for control, the proposed technique offers a more precise solution. In addition, the integration of a coupled proportional controller into the visual axis control method enables the system to stably track dynamic and static targets in real time. In the static target tracking experiment, the proposed method demonstrates effective convergence for targets at different positions in the working area. In the dynamic target tracking experiment, it successfully tracks targets moving at different speeds and along various trajectories. Compared with existing tracking methods, the proposed method has improved tracking performance.
{"title":"A beam pointing and tracking control method for rotating double-prism system based on virtual axis angular deviation strategy","authors":"Zhao Chen , Gaoliang Peng , Wei Zhang , Hongzhao Lin , Hang Li , Zhixiong Li","doi":"10.1016/j.optlaseng.2025.109030","DOIUrl":"10.1016/j.optlaseng.2025.109030","url":null,"abstract":"<div><div>The rotating double-prism system, an emerging beam steering mechanism, achieves optical axis deflection through rotational modulation of two prisms, enabling high-precision angular positioning in free space. Due to the structural configuration of the two prisms arranged in series, the target tracking based on image feedback has strong nonlinear characteristics and coupling within the rotating double prism system. Consequently, the two prisms must be controlled in coordination to effectively deflect the reflected light. This paper introduces an innovative approach to adjusting the boresight by employing virtual axis angular deviation, grounded in the inverse ray tracing method. This method effectively separates the virtual pointing axis from the target visual axis. In contrast to traditional methods that rely only on the equivalent approximate information of image deviation for control, the proposed technique offers a more precise solution. In addition, the integration of a coupled proportional controller into the visual axis control method enables the system to stably track dynamic and static targets in real time. In the static target tracking experiment, the proposed method demonstrates effective convergence for targets at different positions in the working area. In the dynamic target tracking experiment, it successfully tracks targets moving at different speeds and along various trajectories. Compared with existing tracking methods, the proposed method has improved tracking performance.</div></div>","PeriodicalId":49719,"journal":{"name":"Optics and Lasers in Engineering","volume":"192 ","pages":"Article 109030"},"PeriodicalIF":3.5,"publicationDate":"2025-04-22","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143858774","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 : 2025-04-22DOI: 10.1016/j.optlaseng.2025.108980
He Wang , Dewen Cheng , Da Wang , Ximeng Wang , Yongtian Wang
The concept of spatial multiplexing and dual focal planes has emerged as a prominent research focus in the field of near-eye display and optometry. The development of a biocular optical near-eye head-up display featuring spatial multiplexing and dual focal planes capabilities poses a significant challenge. This study introduces a design method for a large-aperture biocular near-eye head-up display based on birdbath optical structure. The system consists of 10 optical components, a transparent LCD display, and a high-brightness LCD display with a specially designed backlight, which magnifies the images displayed by the two LCD displays. The optical system comprises a beam splitter, a curved reflective mirror, 8 single lenses, a transparent LCD display, and a high-brightness LCD display with a specially designed backlight. This system is designed to amplify the visual content shown on the paired LCD displays. In contrast to conventional multifocal optical approaches, the system outlined in this study forgoes the beam-splitting technique. Instead, it places the two LCD displays co-axially in space to achieve spatial multiplexing. Simultaneously, both LCD displays are illuminated by the same backlight module. This approach increases the flexibility of placing transparent LCD displays in three-dimensional space while diminishing the brightness of transparent LCD displays to amplify the defocus stimulation effect within this optical path. Both focal planes are based on 5.5-inch LCD displays. The entire optical system offers a diagonal field of view measuring 30°, an eye box of 100 mm × 70 mm, and an eye relief of 225 mm.
{"title":"A large-aperture biocular virtual reality head-up display system with spatial multiplexing and dual focal planes using birdbath optical structure","authors":"He Wang , Dewen Cheng , Da Wang , Ximeng Wang , Yongtian Wang","doi":"10.1016/j.optlaseng.2025.108980","DOIUrl":"10.1016/j.optlaseng.2025.108980","url":null,"abstract":"<div><div>The concept of spatial multiplexing and dual focal planes has emerged as a prominent research focus in the field of near-eye display and optometry. The development of a biocular optical near-eye head-up display featuring spatial multiplexing and dual focal planes capabilities poses a significant challenge. This study introduces a design method for a large-aperture biocular near-eye head-up display based on birdbath optical structure. The system consists of 10 optical components, a transparent LCD display, and a high-brightness LCD display with a specially designed backlight, which magnifies the images displayed by the two LCD displays. The optical system comprises a beam splitter, a curved reflective mirror, 8 single lenses, a transparent LCD display, and a high-brightness LCD display with a specially designed backlight. This system is designed to amplify the visual content shown on the paired LCD displays. In contrast to conventional multifocal optical approaches, the system outlined in this study forgoes the beam-splitting technique. Instead, it places the two LCD displays co-axially in space to achieve spatial multiplexing. Simultaneously, both LCD displays are illuminated by the same backlight module. This approach increases the flexibility of placing transparent LCD displays in three-dimensional space while diminishing the brightness of transparent LCD displays to amplify the defocus stimulation effect within this optical path. Both focal planes are based on 5.5-inch LCD displays. The entire optical system offers a diagonal field of view measuring 30°, an eye box of 100 mm × 70 mm, and an eye relief of 225 mm.</div></div>","PeriodicalId":49719,"journal":{"name":"Optics and Lasers in Engineering","volume":"192 ","pages":"Article 108980"},"PeriodicalIF":3.5,"publicationDate":"2025-04-22","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143858775","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 : 2025-04-21DOI: 10.1016/j.optlaseng.2025.109021
Pengyan Zhang , Zhiyong Wang , Keyu Tan , Zhuofan Dong , Qidi Zhou , Chuanwei Li , Wei Qiu
The stress in coatings is one of the key factors leading to the failure of thermal barrier coatings (TBCs). This study proposes a testing technique for measuring the stress in topcoat layer of the TBCs using Terahertz Time-Domain Spectroscopy (THz-TDS), based on the specific propagation characteristics of THz radiation in multi-layer materials. In this work, a stress measurement principle was firstly proposed to measure the stress in topcoat layer based on the classic stress-optic law. Then, we experimentally calibrated the stress-optic coefficients of the ceramic topcoat material (ZrO2) required for stress measurement. Based on the proposed measurement principle, an algorithm was designed to determine the loading stress in topcoat layer by analyzing the translation of time-domain pulse of the reflected THz signal. Finally, we designed and conducted verification experiments using a four-point bending sample. The result of experimental measurements aligned well with the theoretical calculations.
{"title":"Measurement of stress in thermal barrier coatings using terahertz time domain spectroscopy","authors":"Pengyan Zhang , Zhiyong Wang , Keyu Tan , Zhuofan Dong , Qidi Zhou , Chuanwei Li , Wei Qiu","doi":"10.1016/j.optlaseng.2025.109021","DOIUrl":"10.1016/j.optlaseng.2025.109021","url":null,"abstract":"<div><div>The stress in coatings is one of the key factors leading to the failure of thermal barrier coatings (TBCs). This study proposes a testing technique for measuring the stress in topcoat layer of the TBCs using Terahertz Time-Domain Spectroscopy (THz-TDS), based on the specific propagation characteristics of THz radiation in multi-layer materials. In this work, a stress measurement principle was firstly proposed to measure the stress in topcoat layer based on the classic stress-optic law. Then, we experimentally calibrated the stress-optic coefficients of the ceramic topcoat material (ZrO<sub>2</sub>) required for stress measurement. Based on the proposed measurement principle, an algorithm was designed to determine the loading stress in topcoat layer by analyzing the translation of time-domain pulse of the reflected THz signal. Finally, we designed and conducted verification experiments using a four-point bending sample. The result of experimental measurements aligned well with the theoretical calculations.</div></div>","PeriodicalId":49719,"journal":{"name":"Optics and Lasers in Engineering","volume":"191 ","pages":"Article 109021"},"PeriodicalIF":3.5,"publicationDate":"2025-04-21","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143851921","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 : 2025-04-21DOI: 10.1016/j.optlaseng.2025.109028
Hang Zhang , Ziwei Zhao , Zhaochuan Hu , Kun Tang , Tianyi Liu , Weidong Tang
In Generation IV nuclear power systems, nuclear fuel performance and plant safety are significantly influenced by the coating thickness of coated fuel particle. However, coated fuel particles have a small enclosed spherical structure and diverse coating configurations, which makes significant challenge for the existing measurement methods. To address this problem, a superpixel-based fuzzy c-means clustering is proposed using colour, texture and position features (SFCM-CTP), for the coating segmentation and thickness measurement of diverse coated fuel particles. Initially, a morphologically-based central particle extraction method is developed to eliminate background interference from neighboring particles. Subsequently, an efficient particle image feature extraction method is proposed, which considers local statistical information, including colour, texture and position features in a comprehensive manner. Based on these features, an effective unsupervised coating segmentation method is proposed by combining simple linear iterative clustering (SLIC) and fuzzy clustering. The experimental results on the constructed particle dataset demonstrate that the proposed method not only performs well in the coating segmentation performance and thickness measurement, but also maintains high accuracy for particles with diverse coating configurations. The Dice values achieve 0.9724, 0.9742, 0.9333 on three configurations of particles, respectively.
{"title":"Superpixel-based fuzzy clustering for the coating segmentation and thickness measurement of diverse coated fuel particles using local statistical features","authors":"Hang Zhang , Ziwei Zhao , Zhaochuan Hu , Kun Tang , Tianyi Liu , Weidong Tang","doi":"10.1016/j.optlaseng.2025.109028","DOIUrl":"10.1016/j.optlaseng.2025.109028","url":null,"abstract":"<div><div>In Generation IV nuclear power systems, nuclear fuel performance and plant safety are significantly influenced by the coating thickness of coated fuel particle. However, coated fuel particles have a small enclosed spherical structure and diverse coating configurations, which makes significant challenge for the existing measurement methods. To address this problem, a superpixel-based fuzzy <em>c</em>-means clustering is proposed using colour, texture and position features (SFCM-CTP), for the coating segmentation and thickness measurement of diverse coated fuel particles. Initially, a morphologically-based central particle extraction method is developed to eliminate background interference from neighboring particles. Subsequently, an efficient particle image feature extraction method is proposed, which considers local statistical information, including colour, texture and position features in a comprehensive manner. Based on these features, an effective unsupervised coating segmentation method is proposed by combining simple linear iterative clustering (SLIC) and fuzzy clustering. The experimental results on the constructed particle dataset demonstrate that the proposed method not only performs well in the coating segmentation performance and thickness measurement, but also maintains high accuracy for particles with diverse coating configurations. The Dice values achieve 0.9724, 0.9742, 0.9333 on three configurations of particles, respectively.</div></div>","PeriodicalId":49719,"journal":{"name":"Optics and Lasers in Engineering","volume":"191 ","pages":"Article 109028"},"PeriodicalIF":3.5,"publicationDate":"2025-04-21","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143851924","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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