Author Affiliations
Abstract
1 School of Instrumentation and Optoelectronic Engineering, Beihang University, Beijing 100191, China
2 College of Electronics and Information Engineering, Sichuan University, Chengdu 610065, China
Light field 3D display technology is considered a revolutionary technology to address the critical visual fatigue issues in the existing 3D displays. Tabletop light field 3D display provides a brand-new display form that satisfies multi-user shared viewing and collaborative works, and it is poised to become a potential alternative to the traditional wall and portable display forms. However, a large radial viewing angle and correct radial perspective and parallax are still out of reach for most current tabletop light field 3D displays due to the limited amount of spatial information. To address the viewing angle and perspective issues, a novel integral imaging-based tabletop light field 3D display with a simple flat-panel structure is proposed and developed by applying a compound lens array, two spliced 8K liquid crystal display panels, and a light shaping diffuser screen. The compound lens array is designed to be composed of multiple three-piece compound lens units by employing a reverse design scheme, which greatly extends the radial viewing angle in the case of a limited amount of spatial information and balances other important 3D display parameters. The proposed display has a radial viewing angle of 68.7° in a large display size of 43.5 inches, which is larger than the conventional tabletop light field 3D displays. The radial perspective and parallax are correct, and high-resolution 3D images can be reproduced in large radial viewing positions. We envision that this proposed display opens up possibility for redefining the display forms of consumer electronics.
tabletop light field 3D display integral imaging compound lens array radial viewing angle Opto-Electronic Advances
2023, 6(6): 220178
1 成都工业学院电子工程学院,四川 成都 611730
2 四川大学电子信息学院,四川 成都 610065
集成成像三维(3D)显示技术具有连续视点、无需助视设备等特点,但普遍存在的视觉串扰现象严重影响立体观看效果。分析图像元在立体视区成像的有效像素区域,推导出图像元上的串扰图像区域分布的变化规律,提出一种立体视区完整的无串扰集成成像3D显示结构。精确设计具有渐变孔径的掩模板阵列,其既能完全透过有效像素光线,使光线向主视区和各阶立体视区成像,保留了集成成像立体视区分布的完整性,又能阻挡串扰像素光线的出射,消除了相邻视区间的串扰,实现了立体视区完整的无串扰集成成像3D显示。提出的结构简单易于实现,有助于集成成像显示技术的进一步推广。
集成成像 立体视区 掩模板阵列 无串扰 激光与光电子学进展
2023, 60(8): 0811020
随着显示技术的发展, 3D显示给人们提供沉浸式体验和更加逼真的立体视觉享受。为了提高成像质量, 准直背光集成成像系统可以收敛像素光线的发散角度, 有效减小中心深度平面后体素的扩散趋势, 进而减小重构体素尺寸, 提高系统分辨率。然而, 由于准直背光系统像素光线的传播路径与传统散射背光系统存在偏移, 导致采样光线的像素映射错误, 进而产生体素漂移和混叠, 影响成像质量。因此, 结合逆向光线追踪技术, 提出一种精准的片源生成方法。该方法建立准直背光系统的光线传播几何, 重新确定采样光线起点和方向, 逆向跟踪每一条光线, 使每根光线信息正确映射到对应像素。实验结果表明, 该方法可以有效矫正光线偏移, 解决体素飘逸和混叠问题, 进而提高系统的成像分辨率。
集成成像 准直背光系统 分辨率 像素映射 体素漂移混叠 integral imaging collimating backlight system resolution pixel mapping voxel drift and aliasing
Author Affiliations
Abstract
1 Optical Communications Laboratory, Ocean College, Zhejiang University, Zhoushan 316021, China
2 Key Laboratory of Ocean Observation-Imaging Testbed of Zhejiang Province, Ocean College, Zhejiang University, Zhoushan 316021, China
Security is one of the key issues in communications, but it has not attracted much attention in the field of underwater wireless optical communication (UWOC). This Letter proposes a UWOC encryption scheme with orthogonal frequency division multiplexing (OFDM) modulation, based on the three-layer chaotic encryption and chaotic discrete Fourier transform (DFT) precoding. The three-layer chaotic encryption processes are bit stream diffusion, in-phase/quadrature encryption, and time-frequency scrambling. With multi-fold data encryption, the scheme can create a keyspace of , effectively resisting brute force attacks and chosen-plaintext attacks. A 3 Gbit/s encrypted OFDM signal is successfully transmitted over a 7 m water channel.
security underwater wireless optical communication chaotic encryption chosen-plaintext attacks Chinese Optics Letters
2022, 20(11): 110601
Author Affiliations
Abstract
1 Wuhan Blood Center-Huazhong University of Science and Technology, United Hematology Optical Imaging Center, Hubei Institute of Blood Transfusion, Wuhan Blood Center, Wuhan, Hubei 430030, P. R. China
2 Wuhan Blood Center-Huazhong University of Science and Technology, United Hematology Optical Imaging Center, Britton Chance Center for Biomedical Photonics, School of Optical and Electronic Information-Wuhan National, Laboratory for Optoelectronics, Huazhong University of Science and Technology, 430074, P. R. China
Folate deficiency has been confirmed to be related to various diseases. Unfortunately, there are few reports on the folate status of Chinese adults. This study aims to evaluate the serum folate status of blood donors in south-central China. In this study, 248 blood donors were included. The information on subjects was collected by a brief questionnaire concerning alcohol consumption habits, smoking habits, fruit and vegetable consumption and physical activity. The serum folate concentration was measured by electrochemiluminescence immunoassay. The geometric mean serum folate concentration was 13.4 nmol l-1 (95% CI, 12.7–14.1). The prevalence of serum folate concentrations below 6.8 nmol l-1 was 5.2% (95% CI, 2.5–8.0). There were significant differences in serum folate concentrations with respect to sex (p-values < 0.05), age (p-values < 0.05), fruit and vegetable consumption (p-values < 0.05), and alcohol consumption habits (p-values < 0.05). The concentration of serum folate increased with age (p-values < 0.05) and fruit and vegetable consumption (p-values < 0.05). Individuals with an age of 30 years or younger were nearly 3.5 times as likely as those aged over 30 years to have an insu±cient level of serum folate (OR = 3.48; 95% CI: 1.01–11.99). An age of 30 years or younger was a risk factor for folate deficiency. Most blood donors had su±cient serum folate concentrations in south-central China. National surveys of folate status should be implemented in China.
Serum folate folate status folate deficiency blood donors folate concentrations. Journal of Innovative Optical Health Sciences
2022, 15(2): 2250008
为了提升全息光学元件集成成像3D显示的离屏距离, 提出了一种采用计算全息波前设计, 对集成成像显示时的每个像素发散角进行精细的调控, 来实现增大3D显示的离屏距离的方法。通过对设计波前进行计算机仿真得到了66.0 mm的连续3D景深, 基于空间光调制器的光学重建实验实现了140.0 mm的集成成像离屏距离和75.0 mm的连续景深3D显示。该方法可以为基于全息光学元件的集成成像3D显示提供一种很好的离屏、3D分辨率增强和景深增强解决方案。
集成成像 3D显示 离屏显示 波前设计 全息光学元件 integral imaging 3D display off-screen display wavefront design holographic optical element
Author Affiliations
Abstract
1 Optical Communications Laboratory, Ocean College, Zhejiang University, Zhoushan 316021, China
2 Key Laboratory of Ocean Observation-Imaging Testbed of Zhejiang Province, Ocean College, Zhejiang University, Zhoushan 316021, China
3 The Engineering Research Center of Oceanic Sensing Technology and Equipment, Ministry of Education, Zhejiang University, Zhoushan 316021, China
Due to the proliferation of underwater vehicles and sensors, underwater wireless optical communication (UWOC) is a key enabler for ocean exploration with a strong reliance on short-range bandwidth-intensive communications. A stable optical link is of primary importance for UWOC. A compact, low-power, and low-cost acquisition, pointing, and tracking (APT) system is proposed and experimentally demonstrated to realign the optical link within 0.04 s, even when the UWOC transmitter and receiver are in relative motion. The system successfully achieves rapid auto-alignment through a 4 m tap water channel with a relatively large number of bubbles. Furthermore, the required minimum illumination value is measured to be as low as 7.1 lx, implying that the proposed APT scheme is robust to dim underwater environments. Meanwhile, mobility experiments are performed to verify the performance of the APT system. The proposed system can rapidly and automatically align moving targets in complex and unstable underwater environments, which can potentially boost the practical applications of UWOC.
acquisition pointing and tracking underwater wireless optical communication Chinese Optics Letters
2021, 19(5): 050604
针对传统集成成像显示技术存在深度反转,需要进行二次成像的问题,提出一种无深度反转的集成成像一次拍摄方法。该方法采用离轴平行式集成成像拍摄结构对三维(3D)场景进行拍摄,通过设计合理的拍摄参数,重排图像元,生成无梯形畸变的图像阵列(EIA),直接用于集成成像显示,解决了传统集成成像的深度反转问题,避免了复杂且繁琐的图像校正和二次成像过程,可快速生成具有正确深度信息的EIA。该方法所获取的EIA在集成成像3D显示实验中重建的3D图像具有正确的深度和逼真清晰的立体显示效果,验证了本文方法的正确性。
成像系统 三维显示 集成成像 深度反转 再现距离