Prototype of a Meter-Wavelength Radio Telescope with Wide Field-of-View

Bulletin of the Lebedev Physics Institute - The scheme and components of a wide field-of-view meter-wavelength radio telescope prototype developed based on an antenna array consisting of 128...     

Three-Dimensional Information Acquisition Using a Compound Imaging System

The TOMBO (thin observation module by bound optics) system is a compound imaging system inspired by a biological visual system. Various interesting features can be utilized in the applications of the TOMBO system: in this paper, we present an effective method for three-dimensional information acquisition. An image captured by the TOMBO system is composed of multiple images observed from several viewpoints. Distance between the TOMBO system and an object can be estimated using disparity of the captured images. A new method for estimation of the object distance is introduced. In the experiment, multiple object distances can be successfully estimated by the proposed method. Using the obtained distances for image reconstruction, we can generate a composite image focussing on multiple objects.     

基于相位辅助的三维数字成像与测量

综述了基于相位辅助的三维数字成像与测量的核心技术.以相机模型为基础,建立了三维数字成像系统模型和三维测量网模型,并介绍了相关的标定技术.在主动立体视觉的理论框架下,综述了相位提取、相位展开、对应点搜索等单视点深度像重建的关键技术.介绍了深度数据后处理技术,其中包括多视点深度像的匹配、融合和简化的代表性算法.同时,对系统...     

大焦深成像系统仿真实验研究

如何增大非相干光学成像系统的焦深是应用光学研究领域的热点问题.本文对采用高次非球面光学掩模板与图像处理相结合增大成像光学系统焦深的新方法进行了深入分析,建立了大焦深成像系统仿真实验模型,并进行了大焦深成像系统仿真实验.实验结果证明了该方法在维持原相对孔径的同时使光学系统在较大的离焦范围内有好的成像质量.实际应用中还要综合考虑模板参量、信噪比等关键因素.     

γ-Ray Holography – Three-Dimensional Imaging of a Local Atomic Structure

γ-ray holography is a novel method for three-dimensional (3D) imaging of a local atomic structure, which utilizes the internal reference idea of holography. The principles of this method will be presented with emphasis on the phase information gained by means of complex holograms. This revised version was published online in August 2006 with corrections to the Cover Date.     

Terahertz Three-Dimensional Imaging Based on Computed Tomography with Photonics-Based Noise Source

Computed tomography has been proven to be useful for non-destructive inspection of structures and materials. We build a three-dimensional imaging system with the photonically generated incoherent noise source and the Schottky barrier diode detector in the terahertz frequency band(90-140 GHz). Based on the computed tomography technique, the three-dimensional image of a ceramic sample is reconstructed successfully by stacking the slices at different heights. The imaging results not only indicate the ability of terahertz wave in the noninvasive sensing and non-destructive inspection applications, but also prove the effectiveness and superiority of the uni-traveling-carrier photodiode as a terahertz source in the imaging applications.     

平面型大光敏元InGaAs线列探测器及其应用

采用晶格匹配的平面型InP／In瞄。Ga叫,As／InP外延材料,设计了一种大光敏元、带有保护环的InGaAs线列探测器。通过I—V9n,4试、扫描电容显微技术（SCM）测试,研究并确定了线列器件的盲元与保护环结构之间的关系。通过设计改进,解决了器件的盲元问题。24×1InGaAs线列短波红外探测在室温20℃、-10mV偏压下,暗电流密度约5nA／cm2。将光敏芯片密封在集成了热电制冷器（TEC）的金属管壳内,组件工作温度5℃,探测器响应光谱在1．0肚m～1．67肚m范围,平均峰值电流响应率为1．3A／W,平均峰值探测率为3．4×10他cm·Hz1/2／W,响应的非均匀性为1．5％。探测器经历一定条件的可靠性筛选试验后,性能未发生明显变化,并进行了航空机载成像应用,成像图片清晰。     

平面型大光敏元InGaAs线列探测器及其应用

采用晶格匹配的平面型InP/In0.53Ga0.47As/InP外延材料,设计了一种大光敏元、带有保护环的InGaAs线列探测器。通过I-V测试、扫描电容显微技术(SCM)测试,研究并确定了线列器件的盲元与保护环结构之间的关系。通过设计改进,解决了器件的盲元问题。24×1 InGaAs线列短波红外探测在室温20 ℃、-10 mV偏压下,暗电流密度约5 nA/cm2。将光敏芯片密封在集成了热电制冷器(TEC)的金属管壳内,组件工作温度5 ℃,探测器响应光谱在1.0 μm~1.67 μm范围,平均峰值电流响应率为1.3 A/W,平均峰值探测率为3.4×1012 cm·Hz1/2/W,响应的非均匀性为1.5%。探测器经历一定条件的可靠性筛选试验后,性能未发生明显变化,并进行了航空机载成像应用,成像图片清晰。     

Generation of Ultrawideband Electromagnetic Radiation by a Vacuum Photodiode with Anode with a Sapphire Input Window

Technical Physics - Generation of ultrawideband electromagnetic radiation by a vacuum photodiode with a plane cesium antimonide photocathode is studied. Thin aluminum plates deposited on a sapphire...     

大孔径静态干涉成像光谱仪的干涉系统分析

从不同方面说明大孔径静态干涉成像光谱仪的特点,介绍其干涉系统的光学原理,分析基于横向剪切干涉仪的干涉系统设计思想,讨论两种高通量大视场横向剪切干涉仪,总结了大孔径静态干涉成像光谱仪的主要优点。     

大口径红外成像系统的光学设计

推导了以反射式两镜系统为主体的红外成像系统中满足光瞳匹配要求的转像透镜的高斯光学参量与两镜系统参量的关系式。当选定红外焦平面的冷屏直径及到焦面的距离后，转像透镜与两镜系统的高斯光学参量之间必须满足这个关系式，才能做到光瞳匹配，这就是冷屏为系统的出瞳．而入瞳是主反射镜的口径。消像差由主镜、副镜的非球面及转像透镜上的一个非球面承担。用实例计算验证了所推导出的公式的可靠性，红外系统的口径取为250mm，红外接收器的冷屏直径为5mm，冷屏到红外像面的距离为20mm。两镜系统主镜的曲率半径选定为-1000mm及-800mm两个值，两镜系统焦距为2000mm，1500mm及1000nm三个。共计算了六种结构参量不同的系统。     

用于离子-分子交叉分子束散射研究的三维离子速度成像装置

本文设计、模拟并搭建了一套由22片圆形金属极板组成的离子透镜系统. 离子透镜的引出极板的开孔处贴有金属栅网,用于屏蔽除推斥极和引出极外的所有其他极板的直流高压对离子-分子交叉区域的影响. Simion模拟表明,在合适的电压配置下,离子透镜可以同时实现速度聚焦和时间聚焦. 这使离子透镜系统能够在三个维度上实现较大的离子体积的速度聚焦,这也是用交叉分子束方法研究离子-分子散射动力学的基本要求. 本文建立了具有单帧多粒子测量和多质量测量能力的三维离子速度测量系统,该系统由微通道板(MCP),P47荧光屏,CMOS相机、光电倍增管(PMT)、高速数字化仪组成. 通过CMOS相机测量离子在荧光屏上的位置,得出垂直于飞行轴的两个速度分量;通过PMT测量离子的飞行时间,得出沿着飞行轴的速度分量. 自主编写了Labview程序,可以实时采集和分析CMOS相机与PMT得到的数据,构建离子的三维速度分布. 单帧多粒子测量是根据同一帧中来自CMOS相机和PMT的多个离子的强度不同,分别对其进行排序,并一一对应起来实现的. 本文用304 nm波长处碘甲烷的光解信号对该三维离子速度成像系统进行了测试和速度校订.     

基于压缩感知的后调制远距离三维成像研究

基于压缩感知(CS)理论,提出使用高功率纳秒脉冲激光器照射远距离目标物体,通过望远系统将目标物体成像到数字微镜阵列(DMD)上,利用DMD加载的调制图像对目标物体的像进行调制(后调制),采用光电倍增管(PMT)作为单像素探测器收集调制后的光强,通过压缩感知计算,完成对远距离目标物体的三维图像重建。将此系统应用于远距离三维成像,通过搭建实验系统,分别对距离为230m和4.5km左右的目标物体完成了绝对距离的测量,实现了64pixel×64pixel的三维成像。同时也证实利用压缩感知进行远距离图像恢复,随着采样率的提高,图像恢复的质量和对比度都有一定程度的提高;目标物体图像越稀疏,重构图像所需的采样次数越少。     

Analysis of Three-Dimensional Large Screen Display Using Polymer-Dispersed Liquid-Crystal Light Valves and a Schlieren Optical System

The performance of a novel three-dimensional (3-D) image projector with polarized glasses is analyzed that consists of polymer-dispersed liquid-crystal light valves and a Schlieren optical system. The cross-talk and the extinction-ratio characteristics of the new 3-D display have been calculated by means of Mueller matrices. Quantitative analyses show that the proposed display achieves small cross talk of less than 1% and sufficient extinction ratio almost the same as the light valve.     

On a Three-Dimensional Gravity Model with Higher Derivatives

The purpose of this work is to present a model for 3D massive gravity with topological and higher-derivative terms. Causality and unitarity are discussed at tree-level. Power-counting renormalizability is also contemplated.     

天文望远镜像差对斑点成像技术的影响

着重研究了采用斑点成像技术处理天文望远镜图像时,光学系统固定像差对图像恢复结果的影响。在详细研究各种恢复天文图像振幅和相位的理论和方法的基础上,建立了一个包括Labeyrie振幅恢复方法和KnoxThompson相位重构方法的恢复扩展目标的斑点成像处理模型,分析了光学系统固定像差对系统传递函数相位分布和目标相位重构的影响：天文目标通过大气成像,固定像差将会被淹没在大气湍流随机起伏中,像差对相位重构没有显著影响。处理图像结果表明,斑点成像技术能同时消除大气湍流和望远镜系统固定像差的影响,得到高分辨力的扩展目标图像。还提出了一种消除光学系统像差的方法。     

Analysis of Light Propagation in a Three-Dimensional Realistic Head Model for Topographic Imaging by Finite Difference Method

Near infrared topographic imaging is a novel non-invasive technique to obtain the activated region in the brain cortex. The light propagation in the head is strongly scattered and this causes results in poor spatial resolution and contrast in the topographic images. Adequate modelling of light propagation in the head in order to deduce the volume of tissue interrogated by a source-detector pair for topographic imaging is very important to improve the quality of image of brain activity. In this study, the light propagation in a three-dimensional realistic head model is calculated by the finite difference method. The geometry of the model is generated from axial slices of an MRI scan. The topographic image is obtained from the change in intensity detected by source-detector pairs caused by the brain activity. The images obtained by two types of source-detector arrangement are compared to evaluate the efficiency of source-detector arrangement. The results show that the double-density arrangement improves the quality of the topographic image of the brain activity.     

氢原子及类氢原子的双波描述

采用双波量子理论对氢原子及类氢原子进行了双波函数描述，讨论了其经典极限。证明了双波函数满足波函数的归一化条件。在双波函数描述下，能量和角动量F的平均值为En和mh。同时求出了r，cosθ,sinθ,cosψ，sinψ和X，Y，Z在双波函数描述的平均值。对力学量f求统计平均值的结果表明，单波函数描述的是氢原子及类氢原子系统的运动状况。只有双波函数描述的是单个粒子的运动状况。     

Development and Optimization of Three-Dimensional Spatial EPR Imaging for Biological Organs and Tissues

The development and optimization procedures for obtaining high-quality three-dimensional spatial electron-paramagnetic-resonance images of large lossy samples at L band are described. Strategies for selecting optimized parameters for projection acquisition, instrumentation, and algorithms for correcting drifts in microwave frequency and inaccuracies in the static and gradient magnetic fields are described. Image reconstruction was performed using a two-stage filtered back-projection method with spectral deconvolution. With this instrumentation, correction algorithms, and image reconstruction method, spatially accurate 3D images of radical distribution were observed in complex phantoms using 0.5 mM nitroxide labels. The results indicate that high-quality images of lossy samples, including biological organs and tissues of up to 25 mm in size, could be obtained in a reasonable time with submillimeter resolution.