Tingqin Lai 1,2Xiaolin Liang 1,2Yi Zhu 3Xinyi Wu 1,2[ ... ]Shihai Sun 1,2,*
Author Affiliations
Abstract
1 School of Electronics and Communication Engineering, Sun Yat-sen University, Shenzhen 518107, China
2 Shenzhen Campus of Sun Yat-sen University, Shenzhen 518107, China
3 Tsinghua Shenzhen International Graduate School, Tsinghua University, Shenzhen 518055, China
Recently, there has been increased attention toward 3D imaging using single-pixel single-photon detection (also known as temporal data) due to its potential advantages in terms of cost and power efficiency. However, to eliminate the symmetry blur in the reconstructed images, a fixed background is required. This paper proposes a fusion-data-based 3D imaging method that utilizes a single-pixel single-photon detector and millimeter-wave radar to capture temporal histograms of a scene from multiple perspectives. Subsequently, the 3D information can be reconstructed from the one-dimensional fusion temporal data by using an artificial neural network. Both the simulation and experimental results demonstrate that our fusion method effectively eliminates symmetry blur and improves the quality of the reconstructed images.
single-pixel imaging single-photon imaging millimeter-wave radar neural network 
Chinese Optics Letters
2024, 22(2): 022701
Author Affiliations
Abstract
1 Tsinghua Shenzhen International Graduate School, Tsinghua University, Shenzhen 518055, China
2 Department of Precision Instrument, Tsinghua University, Beijing 100084, China
Lens-free on-chip microscopy with RGB LEDs (LFOCM-RGB) provides a portable, cost-effective, and high-throughput imaging tool for resource-limited environments. However, the weak coherence of LEDs limits the high-resolution imaging, and the luminous surfaces of the LED chips on the RGB LED do not overlap, making the coherence-enhanced executions tend to undermine the portable and cost-effective implementation. Here, we propose a specially designed pinhole array to enhance coherence in a portable and cost-effective implementation. It modulates the three-color beams from the RGB LED separately so that the three-color beams effectively overlap on the sample plane while reducing the effective light-emitting area for better spatial coherence. The separate modulation of the spatial coherence allows the temporal coherence to be modulated separately by single spectral filters rather than by expensive triple spectral filters. Based on the pinhole array, the LFOCM-RGB simply and effectively realizes the high-resolution imaging in a portable and cost-effective implementation, offering much flexibility for various applications in resource-limited environments.
lens-free on-chip microscopy LED phase retrieval pinhole array 
Chinese Optics Letters
2024, 22(2): 021101
作者单位
摘要
1 清华大学深圳国际研究生院,广东 深圳 518055
2 西北工业大学物理科学与技术学院,陕西 西安 710072
3 西北工业大学深圳研究院,广东 深圳 518063
在数字全息粒子场成像中,粒子衍射的孔径角很小,重构时具有很长的焦深,造成轴向定位精度远低于横向定位精度。增大照明波长,相当于增大粒子孔径角,因此可得到更高的轴向定位精度。采用红外相干光源照明粒子场,在不提升算法和系统复杂度的前提下提升数字全息粒子场重构的轴向定位精度。从理论上分析数字全息粒子场重构中焦深与轴向定位精度的关系,并分别仿真分析绿光、红光及红外光照明时的粒子场全息重构,分别开展了基于这3种光源的聚苯乙烯微球粒子场全息成像实验。仿真和实验结果研究表明,相比红光,红外光源使焦深减小了约19%,而相比绿光,焦深减小了约39%。增加波长可以减弱离焦像的层间干扰,从而提高了轴向定位精度。
数字全息 粒子场 红外光 轴向定位精度 
激光与光电子学进展
2024, 61(2): 0211022
作者单位
摘要
清华大学深圳国际研究生院,广东 深圳 518055
提出一种基于螺旋波带片的无透镜编码边缘增强成像技术,用螺旋波带片和图像传感器组成成像系统,对拍摄的图片进行反向传播重建。在反向传播中,取强度值可实现各向同性边缘增强成像,取实部或虚部可实现各向异性边缘增强成像。对取实部实现各向异性边缘增强成像进行理论推导,引入初始相位因子实现方向可选择的各向异性边缘增强成像。数值模拟和实验验证了理论分析与实验结果的一致性。对基于菲涅耳波带片、螺旋波带片的无透镜成像系统的边缘增强重建结果进行定量对比分析,结果证明基于螺旋波带片的无透镜成像系统更适用于边缘增强成像。所提技术在缺陷检测、智能识别和虚拟现实技术等领域具有广阔的应用前景。
无透镜成像 边缘增强 螺旋波带片 编码掩模 图像重建 
激光与光电子学进展
2023, 60(8): 0811022
Author Affiliations
Abstract
1 Tsinghua Shenzhen International Graduate School, Tsinghua University, Shenzhen 518055, China
2 Department of Precision Instrument, Tsinghua University, Beijing 100084, China
In this Letter, a single scattering turbulence model in a narrow beam case for ultraviolet (UV) communication is proposed based on the division of the effective scattering volume. This model takes the variation of atmospheric scattering, absorption, and turbulence in different paths into account. Meanwhile, the applicable transceiver configurations of this model are provided by analyzing path loss error caused by the single scattering assumption in the UV channel. Furthermore, we investigate the effect of turbulence on the probability density function of the arriving power in both coplanar and non-coplanar scenarios. The averaging effect of multipath propagation on the arriving power’s fluctuations is presented. Then, the bit-error-rate performance is also studied. This work provides an efficient way for UV turbulence channel estimation.
ultraviolet communication single scattering approximate model atmospheric turbulence 
Chinese Optics Letters
2020, 18(12): 120602
作者单位
摘要
清华大学深圳研究生院 光盘国家工程研究中心深圳分中心, 广东 深圳 518055
由于采用发光二极管(LED)制作显示薄膜, 所以可以改善常规显示屏有缝拼接, 刷新频率低, 应用场合相对窄的缺点, 如果显示薄膜的衬底材料为聚碳酸酯(PI)薄膜, 薄膜后的印刷电路板(PCB)也做成柔性的, 那么显示屏就是柔性LED显示屏了, 可以应用到更多的场合。显示屏的核心设计是显示薄膜的设计, 此设计制作的柔性显示薄膜, 要求像素间距为1 mm, 折弯半径小于10 cm。最后采用lighttools专业软件进行仿真分析, 并进行了一系列具体实验, 测出这种像素间距为1 mm的样品折弯半径为3.1 cm, 可以看出: 实验结果和仿真分析有较大吻合性 , 说明这种设计有充分的可行性。
光学结构设计 显示薄膜 荧光粉 lighttools仿真 design of optical structure display film phosphor simulation in lighttools 
应用光学
2019, 40(5): 871
作者单位
摘要
1 清华大学深圳研究生院, 广东 深圳 518055
2 清华大学精密仪器系, 北京 100084
3 宁波大学物理系光学研究所, 浙江 宁波 315211
数字微镜器件(DMD)具有较高的刷新速率和衍射效率,是理想的动态计算全息图加载器件。采用发光二极管(LED)作为光源来代替激光可以有效减少由激光的时间和空间相干性带来的散斑噪声。提出了一种以LED为光源、以DMD为计算全息图承载器的全息显示系统。研究了DMD进行全息显示的调制特性,分析了LED作为再现光源导致像质变差的原因,并用数值仿真的方法验证了LED的相干性和准直度对DMD全息显示系统再现像像质的影响。根据仿真分析结果,采用滤色片和空间滤波器来提高LED的相干性,同时采用非球面准直透镜来改善光的利用效率,最终得到了较好的显示效果。
全息 全息显示 部分相干光 数字微镜器件 发光二极管 计算全息图 
光学学报
2016, 36(7): 0709001
作者单位
摘要
1 清华大学 深圳研究生院, 广东 深圳 518055
2 中山大学 中法核工程与技术学院, 广东 珠海 519000
通过微电子机械技术(MEMS)在抛光的熔融石英基材表面制作了平面精度达到0.4 μm的超大单片面积的全息透镜。采用了分辨率达到0.2 μm的步进投影式拼接光刻, 适合石英基材的专用等离子耦合刻蚀(ICP)干法刻蚀技术, 特殊的物理清洗方法, 以及相关的多项辅助工艺。透镜理想面形横截面曲线为分段抛物线, 每一片由23个柱状结构单元周期横向排列构成, 采用等深度不等宽度的4台阶结构拟合, 单元宽度约为2.966 mm。在4 in(10.16 cm)圆片上, 获得了单片尺寸为68 mm×68 mm的方形透镜。采用接触式台阶仪, 扫描电子显微镜(SEM), 高倍光学显微镜等方法进行不同阶段检测。结果显示: 台阶平面精度为0.4 μm, 垂直精度为30 nm, 有非常好的立墙陡直度和刻蚀均匀性。此工艺方案可实现小规模批量生产, 成本适中, 可以直接用于制作6 in(15.24 cm)以上同等级要求的石英透镜, 经适当改进也可用于蓝宝石等基底材料的制作。
微电子工艺 光刻 全息透镜 等离子耦合干法刻蚀 微机电系统(MEMS) micro electronic process photo lithography hologram lens Inductively Coupled Plasma(ICP) dry etch Micro-electro-mechanical System(MEMS) 
光学 精密工程
2015, 23(11): 3107
Author Affiliations
Abstract
In holographic encryption, double random-phase encoding in the Fresnel domain (DRPEiFD) is a prevalent encryption method because it is lensless and secure. However, noises bring adverse effects during decryption. In this letter, we introduce quick-response (QR) coding during encryption to resist noises. We transform the original information into a QR code and then encrypt the code as a hologram through DRPEiFD. To retrieve the input, we decrypt the hologram in the opposite manner to the encryption and subsequently obtain a QR code with noises. By scanning this code with proper applications in smartphones, we can obtain a noise-free retrieval. Numerical experiments and images scanned by a smartphone are shown to validate our proposed method.
060.4785 Optical security and encryption 070.4560 Data processing by optical means 090.1760 Computer holography 100.4998 Pattern recognition, optical security and encryption 
Chinese Optics Letters
2014, 12(1): 010601
作者单位
摘要
1 清华大学 深圳研究生院, 广东 深圳 518055
2 清华大学 精密仪器系, 北京 100084
主要研究并设计了消除自由立体前投影显示亮线的增透膜系。分析了显示亮线产生的原因,该亮线是由微柱透镜表面的反射造成的。选用Ta2O5和SiO2设计了13层高硬度和高透过率的增透膜。三者的热膨胀系数基本一致,避免了膜层的断裂。该膜系的SiO2膜层总厚度大于1μm,大大提高了增透膜的耐摩擦性。Ta2O5膜层总厚度只有33.1nm,大大减少了高温蒸发时间,避免了PMMA板材的高温变形。镀膜后透镜板在可见光波段透过率理论最高可达98%左右,消除了表面反射亮线,大大提高了柱镜板的透过率。
微柱透镜 自由立体显示 前投影 亮线 增透膜 microcylindrical lens autostereoscopic display front projection bright line antireflection coating 
半导体光电
2013, 34(6): 1043

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