微偏振片阵列成像的非均匀校正研究

针对传统的非均匀校正算法难以校正偏振成像的非均匀问题,提出了一种新的矩阵校正算法。分析了偏振成像与非偏振成像的非均匀性的不同表现,阐述了微偏振片阵列成像的非均匀产生机理,指出了采用非偏振成像非均匀校正方法的失效原因。在构建偏振成像系统对入射偏振光源的响应模型基础上,提出了矩阵校正法。实验部分给出了矩阵校正法对均匀偏振场本底图像和信息丰富场景图像的校正效果,定量分析结果表明,矩阵校正法将均匀本底图像的非均匀性降至校正前的10%左右。     

基于像素偏振片阵列的实时水下目标成像技术

借助偏振成像可以增强水下目标的探测效果。传统的偏振成像方法需要光学检偏器的机械转动来实现,这限制了其在水下的实时探测性能。采用基于像素偏振片阵列图像传感器开发的相机设计了一种水下实时成像系统。系统通过阵列上排布的四向微偏振片一次性捕获四向偏振图像,从而全局估算背景杂散光的偏振角和偏振度。然后利用偏振信息反解得到杂散光光强,最后借助水下成像物理模型得到去散射后的目标增强图像。实验结果表明,将像素偏振片阵列图像传感器应用到水下成像能够有效增强水下图像的对比度,且成像处理过程实时快速,进一步提高了水下目标的探测效率。     

基于微偏振阵列的干涉型高光谱偏振成像方法

光谱和偏振辐射特性是实现精细目标识别的重要光学参量,融合光谱和偏振信息分量的光谱偏振成像探测技术有效利用两者的互补性,提高在复杂背景环境下的目标识别能力,在环境监测、军事侦察和大气分析等领域具有巨大的发展潜力。围绕目标的光谱和偏振信息探测问题,研究了一种基于微偏振阵列的干涉型高光谱偏振成像技术。在研究Sagnac干涉型高光谱成像技术的基础上,利用微偏振阵列调制原理引入Stokes偏振分量信息探测。通过分析系统的工作原理,设计了系统的干涉成像光路模型,并对光谱信息反演方法以及偏振信息提取方法进行了讨论分析。搭建了实验装置,对实际场景目标进行了光谱偏振成像实验,得到了较好的实验结果。研究表明:该光谱偏振成像技术不仅具有高光通量、高光谱分辨率的优点,而且能够实现偏振信息的同步获取。     

用于偏振成像的液晶微偏振阵列研究进展

微偏振阵列是分焦平面偏振计的核心元件.相较于纳米线栅阵列,液晶偏振阵列有着设计灵活、工艺简便、性能稳定等独特优势,有望实现高性价比、高精准度的偏振测量与成像.本文综述了近年来国内外科研团队针对液晶微偏振阵列展开的研究,系统阐述了基于宾主型、偏振旋转型和相位延迟型3大类液晶偏振阵列的器件结构和工作原理,不同的液晶排列结构...     

基于偏振成像的水下图像复原技术研究最新进展

在水下环境中,悬浮的散射颗粒对光场的散射和吸收作用导致成像清晰度显著下降。基于偏振成像的水下图像复原技术是实现水下清晰成像的有效方法之一。该技术利用散射光的偏振特性,分离场景光和散射光,估计散射光强和透射系数,实现成像清晰化。近年来,偏振成像技术已广泛、高效地应用于水下图像复原和水下目标识别等诸多领域。水下偏振图像复原技术作为光学成像技术和图像处理技术的交叉领域,引起了广泛的关注并取得了大量优秀的研究成果。文中主要介绍了基于偏振成像的水下复原技术的基本原理、偏振信息处理方法和最新发展现状,综述了近年来偏振水下图像复原技术代表性的改进型方法。     

基于盖革APD阵列的微扫描激光成像技术

盖革APD阵列探测的激光成像雷达具有高灵敏度、高帧频、宽视场、坚固、体积小等优点,成为了激光成像雷达发展的趋势。但目前APD阵列像元填充比低,器件阵列少,无法满足高分辨率激光成像的要求。为了解决该问题文中提出采用激光点阵发射的方法与APD阵列像元一一对应,采用拼接技术提高成像分辨率,采用微扫描技术提高激光成像视场。通过构建实验系统,完成了室外试验,成像效果良好,使用现有APD探测器（3232）将系统空间分辨率提高了四倍（6464）,提高了激光三维成像能力。     

基于不同微透镜阵列参数的集成成像微图像阵列生成方法

提出一种基于不同微透镜阵列参数的集成成像微图像阵列生成方法。在该方法的拍摄过程中,首先通过微透镜阵列1拍摄三维场景获得微图像阵列1,再通过一个包括虚拟显示和虚拟拍摄两个步骤的像素映射算法,生成与微图像阵列1参数不同的微图像阵列2。在显示过程中使用的微透镜阵列2与拍摄时的微透镜阵列1具有不同的参数,微图像阵列2通过微透镜阵列2重建出全真的3D图像,重建的3D图像没有图像缩放和畸变。同时本文还推导了微图像阵列1、2和微透镜阵列1、2各参数应满足的数学关系。实验结果验证了理论推导的正确性。     

基于不同微透镜阵列参数的集成成像微图像

提出一种基于不同微透镜阵列参数的集成成像微图像阵列生成方法。在该方法的拍摄过程中, 首先通过微透镜阵列1拍摄三维场景获得微图像阵列1, 再通过一个包括虚拟显示和虚拟拍摄两个步骤的像素映射算法, 生成与微图像阵列1参数不同的微图像阵列2。在显示过程中使用的微透镜阵列2与拍摄时的微透镜阵列1具有不同的参数, 微图像阵列2通过微透镜阵列2重建出全真的3D图像, 重建的3D图像没有图像缩放和畸变。同时本文还推导了微图像阵列1、2和微透镜阵列1、2各参数应满足的数学关系。实验结果验证了理论推导的正确性。     

四通道阵列偏振成像自适应光学系统设计

在大气湍流影响下,为了实现对远距离目标偏振成像,基于孔径分割技术和自适应补偿技术,设计了四通道阵列偏振成像自适应光学系统。偏振成像部分采用四通道阵列结构,每个偏振通道获取目标不同偏振分量的强度图像,从而实现同时偏振成像。采用闭环自适应系统对波前畸变进行实时补偿。光学系统的设计焦距为364 mm,F数为2.5,工作波长为1.06 μm,半视场角为±0.3°。设计结果表明,系统成像性能接近衍射极限,可以实现同时偏振成像和波前畸变的校正。     

红外偏振成像技术研究

偏振成像技术是近年来国内外成像技术研究的重点,具有重要的应用价值。概述了红外偏振成像系统原理、组成及其特点,介绍了该技术国内外的研究概况,重点分析了中波/长波红外偏振成像装置以及红外偏振成像技术在人工目标识别上潜在的优势。最后对红外偏振成像技术的未来发展趋势进行了展望。     

Polarization reconfigurable microstrip phased array

In this paper, the design and the experimental validation of a polarization reconfigurable microstrip phased array is presented. The reconfigurability between the right-handed (RHCP) and left-handed (LHCP) circular polarization is achieved using electronic switches (PIN diodes) combined with truncated corners microstrip radiators. In the design, special attention was given to the matter of reducing back lobe radiation effects using the concept of asymmetric positioning of the radiators with respect to the ground plane. Afterward, the main lobe axial ratio behavior for several beam steering and side lobe level conditions are investigated. Finally, the polarization reconfigurability is achieved and the design is validated through the good agreement between theoretical and experimental results.     

共形天线阵列极化分集问题

在多模复合制导模式下,被动雷达导引头(PRS)可采用共形天线阵列接收入射信号。共形天线通常为线极化天线,将其摆放在弹体的一周,天线阵列的接收信号将出现极化分集问题。针对该问题,建立了在极化分集条件下共形天线阵列接收信号的数学模型,理论推导极化分集对干涉仪方法测向性能的影响,以及分析干涉仪方法能够正确测向的前提条件,通过计算机仿真实验验证了研究结论的有效性。该文给出了解决共形天线阵列极化分集问题的研究思路。     

Hybrid IRCCD imaging array

A hybrid IRCCD for high background application has been successfully fabricated. The device consists of fifty Hg0.7Cd0.3Te detector diodes of 50-µm × 50-µm sensitive areas and a silicon CCD maltiplexer with input circuits on 40-µm centers having bucket background subtraction and blooming protection circuits. The noise-equivalent power (NEP) of the IRCCD is 5 × 10^-14W-Hz^-1/2at background photon flux level of 4 × 10¹⁵photons . cm^-2s^-1, integration time of 2 × 10^-5s, and clock frequency of 3 × 10⁶Hz. The noise source of the detector diodes limits the IRCCD performance. The IRCCD is also evaluated with the real-time raster-scanned thermal images displayed on a CRT monitor. Two-dimensional images are generated by using a scanning mirror. A fixed-pattern noise is reduced by comparison of an object video to the reference video stored in a memory. A noise-equivalent temperature difference of the system is 0.6°C at a frame rate of 30 Hz. Instantaneous field of view is 1 mrad × 1 mrad and the field of view of the system is 12° × 5.7°.     

Nonuniformly spaced array imaging

An image reconstruction algorithm for randomly spaced array imaging is developed. Based on the fact that the sampled bistatic Fourier space data can occupy almost the same region as that for rotating object imaging if the angular coverage is suitably defined, the range-Doppler reconstruction method developed in the rotating object imaging can be applied to the uniformly spaced circular array imaging case. When the array elements are randomly spaced, three more steps, a range alignment, a phase compensation, and an interpolation, are required to preprocess the measured signals. Experimental and numerical results have shown the effectiveness of the proposed algorithm     

InSb charge-injection device imaging array

InSb CID arrays, in both 1 × 32 line and 16 × 24 two-dimensional format, have been successfully fabricated via a multilayer MIS processing technique. With the 1 × 32 line arrays, two-dimensional images were generated using a scanning mirror and a computer signal-conditioning technique. In this experiment the small temperature difference of a man's face was revealed. Two-dimensional, 16 × 24 area arrays have also been demonstrated in a staring mode by displaying real time raster-scanned IR images directly on a X-Y CRT monitor. The unprocessed IR video signal produced a sharp, clearly recognizable display with no sign of blooming, and exhibited excellent operating characteristics. Theoretical analysis showed that, at low sample rates, background limited performance (BLIP) can be obtained at background photon flux levels of as low as mid-10¹²photons/s . cm². The dominant noise source, in this case, is the integrated dark current shot noise. For operation at high sample rates, however, the bandwidth-dependent noise sources limit the array performance and, thus, BLIP occurs at higher background levels. The analysis has been confirmed by measured data on line arrays, resulting in good agreement between the theoretical curve and the experimental data.     

Yagi-Uda array for millimetre-wave imaging

An imaging array consisting of five Yagi-Uda antennas in a dielectric has been constructed for 50 GHz that has antenna patterns suitable for millimetre-wave applications. Crosstalk levels of less than -30 dB between adjacent antennas in an f/1.0 imaging array have been measured in 5 GHz model experiments.<>     

Polarization matching of wide angle conically scanned phased array beams

Multisatellite communication may require coverage of a segment of the geosynchronous arc as large as60deg. A properly oriented ground station antenna can cover the above segment by means of a beam whose axis traces a conical surface (i.e., conically scanned beam). The antenna consists of two linear arrays feeding an imaging reflector arrangement through a polarization diplexer. This diplexer separates the incoming wave into two orthogonal polarizations without loss. In general, the polarization of the wave reflected by the diplexer does not remain the same as that corresponding to the feed array as the beam is scanned (polarization mismatch). This mismatch can cause an appreciable degradation of the antenna gain when the feed array is scanned in certain directions. For example, a ground station located at Seattle, WA could experience 3.6 dB reduction in gain due to polarization mismatch when the antenna beam is scanned along a60degsegment of the geosynchronous satellite arc. The above polarization mismatch loss can be substantially reduced by the use of two properly inclined polarization rotators. These devices are sufficiently broadband to cover the entire 12/14 GHz satellite communication band. Design formulas for the inclination angle between the polarization rotators are presented. Applying these formulas we have reduced the above-mentioned polarization mismatch loss to less than 0.01 dB.     

阵列测量方式下的电阻率井壁成象

电阻率成象测井是石油测井中最新一代的测井方法 ,对测井仪器响应的精确模拟 ,可以为此类仪器的优化设计和资料解释提供依据。针对电阻率成象仪激励条件比较复杂的特点 ,同时考虑井下地层固有的非均质性 ,选用有限元方法对仪器产生的位场进行分析 ,并对一些典型的地层模型进行模拟 ,给出其电阻率井壁成象结果 ,直观反映井壁地层特征     

同时偏振成像仪检偏方位校正研究

同时偏振成像探测技术是近年发展起来的新型遥感探测技术,该技术采用分振幅方式,在同一个探测器上同时获得被探测目标0、45、90、135四个偏振方向的偏振强度图。这四个检偏方位受到仪器自身偏振效应、偏振器件误差和膜层的影响会发生偏离,为了保证偏振探测精度,对系统的四个检偏方位采用Equator-Poles 定标和曲线拟合的方法进行校正,两种方法测量结果一致性在0.4%以内。线偏振度实测精度与理论分析精度都在2%以内,这验证了检偏方位校正的有效性。     

基于压缩感知的偏振光成像技术研究

偏振成像技术是一种基于目标自身辐射或反射信号中所包含的偏振信息获取物体图像的方法,尤其在人工目标的探测和表面识别方面,相对光强度探测方式具有独特的优势。针对传统的偏振成像技术在复杂的成像环境中成像距离短和成像质量差的缺点,提出了一种基于压缩感知的新型偏振光成像技术。阐述了压缩感知理论的基本原理,构造了合适的采样矩阵和重构算法,设计了具体的成像系统,并通过压缩感知偏振成像实验证明了该成像技术的可行性。空气中实验结果表明,该成像系统能够重构出预先放置目标靶的偏振图像。此外在现有的实验条件基础上讨论并提出了几种改进系统成像质量的措施。