双通道曲面棱镜高光谱成像系统设计

为满足航空航天载荷宽谱段、小型化的探测需求,提出一种双通道曲面棱镜高光谱成像系统的设计方法,实现单台光谱成像仪可同时覆盖可见光和短波红外两个波段。可见光和短波红外两个通道共用一个离轴三反前置成像系统和部分光谱系统,通过在像面前放置的分色片进行分光,使得可见光由分色片全部反射,短波红外由分色片全部透射,反射光和透射光分别被不同的探测器接收。根据此方法设计了谱段范围为420～2500nm的双通道光谱成像系统。结果表明,该系统结构简单,光学成像性能良好,光学总长度小于350mm。与传统的宽谱段光谱成像方法相比,该方法可以满足系统的小型化和低成本需求,适用于航空航天遥感应用。     

基于非负矩阵分解的中红外地表特性光谱重建方法

在中红外遥感领域,高光谱地表反射率/发射率等地表特性具有极高的应用价值和应用需求,但利用卫星遥感手段难以获取吸收波段的高光谱地表反射/发射特性,且通过光谱重建获取全波段的地表特性方法仍存在很多问题。为解决中红外全波段地表特性光谱重建所面临的难题,基于约翰霍普金斯大学(Johns Hopkins University, JHU)地物波谱库和中分辨率成像光谱仪(MODIS)短波红外和中红外地表多光谱卫星产品,提出了一种利用非负矩阵分解(NMF)重建高光谱地表反射率的方法,对2.5～5.0μm中红外光谱范围内的地表反射/发射率进行光谱重建,重建后的光谱分辨率可达10 nm。首先基于JHU地物波谱库选取4种典型地物类型(土壤、植被、人造材料和岩石),建立地物光谱库样本信息,再利用MODIS传感器光谱响应函数,根据等效计算公式将2.0～5.0μm波段范围反射率结果重采样到10 nm光谱间隔、共301个波段,得到JHU地表反射率光谱数据集。对光谱数据集进行非负矩阵分解处理,提取4条端元向量光谱曲线,结合MODIS短波红外和中红外4个波段(2.13、 3.75、 3.96和4.05μm)的全球月均地...     

共口径中波/短波偏振红外成像光学系统

对中波/短波偏振红外成像光学系统进行了研究,设计了一个新颖的共口径中波/短波偏振红外成像光学系统.该光学系统由全反射式无焦光学系统、分束镜、二级镘远系统、偏振组件和红外物镜系统组成,为了约束主反射镜、双面反射镜、分束镜和偏振片的H径,创造性地采用了_三次成像光学系统.光波经无焦光学系统后被分束镜分成中波红外波段(3～5 gm)和短波红外波段(1～2.5弘m).然后分别经两个物镜系统会聚到两个探测器上.实现了双波段共1:3径成像.给出了光学系统的设计结果.像质良好,满足整机使用要求.     

多波段红外离轴三反光学系统的设计

单一红外波段的光学系统在无人机对地侦察时接收到目标信息量较少,也易受环境的影响甚至无法探测到目标,严重影响了侦察的效率.分析了多波段红外光学系统成像原理及设计方法,最终选取反射式结构形式设计了一款焦距为50mm、全视场为12°×10°的离轴三反红外光学系统,该系统可用于短波红外成像、中波红外成像,以及长波红外成像.各个...     

面向火星表面层状硅酸盐识别的模型研究

层状硅酸盐是火星表面含水矿物的主要存在形式之一,也是比较火星不同沉积物和水蚀作用程度的指示矿物,因此构建其识别模型对研究火星的地质演化极其重要。短波红外和热红外谱段对矿物的基团、离子光谱响应机理不同,具有不同的识别优势,然而国内外联合两者识别层状硅酸盐矿物则鲜有研究。基于USGS光谱库数据,面向火星探测器紧凑型侦查成像光谱仪(CRISM)和热辐射成像系统(THEMIS),在层状硅酸盐的光谱响应机理研究基础之上,分别构建短波红外识别模型与热红外模型,进而结合短波红外和热红外谱段,基于Fisher判别分析构建层状硅酸盐的综合识别模型。交叉验证表明,综合模型识别精度优于短波红外模型和热红外模型,对90.6%的矿物样本正确识别,有效提高了层状硅酸盐的识别精度。     

向短波红外延伸的微光夜视技术及其应用

对传统的微光像增强器与向短波红外延伸的InGaAs光阴极像增强器进行了比较,分析了通过调节组分而使响应波段覆盖夜天光辐射主要波段的InGaAs材料特性,揭示了以InGaAs半导体材料为光阴极的像增强器将在夜间具有更高的量子效率和响应度。介绍了InGaAs器件技术的国内外研究现状,InGaAs光阴极微光器件在短波红外波段的辐射响应是传统像增强器的100~1 000倍,InGaAs全固态探测器可在0.4 m~1.7 m宽光谱成像,在0.9 m~1.7 m范围的量子效率大于80%,表明该器件在激光探测、远距离定位与跟踪、情报侦察、夜间辅助驾驶等方面可以获得广泛应用。     

可见-短波红外波段光谱模块光机装调及分析

介绍了自行研制的辐射仪器的光谱模块,其光谱范围覆盖可见-短波红外波段(400 nm~2 500 nm),讨论了光谱模块的装调方法并对装调结果进行了分析研究。辐射仪器由3个光谱模块组成,分别是可见波段光谱模块(400 nm~1 000 nm),近红外波段光谱模块(900 nm~1 700 nm)和短波红外波段光谱模块(1 600 nm~2 500 nm),光谱模块的探测单元均以平场凹面光栅分光,线阵探测器探测信号,光谱模块的光机组件主要包括光纤头、狭缝、反射镜组件、光栅组件和探测器组件等。鉴于光谱模块的光机装调效果与其光机设计息息相关,装调结果的好坏能反映光机设计的优劣,针对光谱模块的光机设计特点进行了光机装调。光机装调分析结果表明:3个光谱模块的波长分辨率分别优于4 nm,15 nm和20 nm,达到了仪器的设计指标,验证了光机设计、装调的合理性。     

基于垂直层叠结构的可见/近红外双波段传感器研究

提出了基于垂直层叠结构的双波段传感器,该结构为同时对可见波段和近红外波段进行成像提供了可能。它的基本原理是利用不同波长的光在硅材料中穿透深度的非线性分布,即:短波长的可见光主要在表面被吸收,长波长的近红外光则主要在更深的位置被吸收。通过垂直层叠结构,抽取不同深度的光生载流子,即可以得到相应波段的成像信息。数值仿真分析表明,结构参量为D1=2μm,D2=18μm的结构能在400~1200 nm波长范围得到响应峰值波长为550 nm和1000 nm的最佳可见/近红外响应。     

星载10 m合成孔径相干成像望远镜和波前估计

针对天文观测和深空探测需求，提出了星载10 m合成孔径相干成像望远镜概念和形式。给出了波长可调谐激光本振相干探测器形式，分析了大口径衍射薄膜镜的双波段实现方式和系统主要参数。提出了基于子镜结构的光学合成孔径相干成像算法，给出了基于相位恢复的阵列形变误差波前估计仿真结果，由于多个子镜所接收复信号的成像处理在计算机软件中完成，相比传统望远镜，可降低对微调机构等硬件的精度要求。该望远镜在短波红外1.45～1.65μm光谱范围内的中心波长角分辨率为0.15μrad；在中波红外4.55～4.75μm光谱范围内的中心波长角分辨率为0.46μrad，其探测灵敏度在原理上是传统10 m口径望远镜的约2.8倍。     

短波红外棱镜-光栅-棱镜成像光谱仪光学系统设计

提出了一种基于棱镜-光栅-棱镜分光器件的短波红外成像光谱仪光学系统,该系统由离轴三反射式望远物镜、准直镜、棱镜-光栅-棱镜和会聚镜组成,光谱覆盖950～2 500 nm,空间视场达到22.5°.在实现宽视场、宽波段设计的同时,优化设计了棱镜-光栅-棱镜分光器件的各个参量.通过偏斜会聚镜光轴和棱镜-光栅-棱镜光轴在光谱维...     

基于Shearlet变换的自适应图像融合算法

针对多聚焦图像与多光谱和全色图像的成像特点,结合Shearlet变换具有较好的稀疏表示图像特征的性质,提出了一种新的图像融合规则.并基于此融合规则,提出了基于Shearlet变换的自适应图像融合算法.在多聚焦图像的融合算法中,分别对聚焦不同的图像进行Shearlet变换,并基于本文提出的融合规则,对分解后的高低频系数进行融合处理. 通过与多种算法的比较实验证明了本文提出的算法融合的图像具有更高的清晰度和更加丰富的细节信息.在多光谱和全色图像的融合处理中,提出了一种基于Shearlet变换与HSV变换相结合的图像融合方法.该算法首先对多光谱图像作HSV变换,将得到的V分量与全色图像进行Shearlet分解与融合,在融合过程中对分解系数选用特定的融合准则进行融合,最后将融合生成新的分量与H、S分量进行HSV逆变换产生新的RGB融合图像. 该算法在空间分辨率和光谱特性两方面达到了良好的平衡,融合后的图像在减少光谱失真的同时,有效增强了空间分辨率. 仿真实验证明,本文算法融合的图像与传统的多光谱和全色图像融合算法相比,具有更佳的融合性能和视觉效果.     

基于单次曝光光场成像的全焦图像重建技术

为了实现大景深信息全焦面高质量成像,提出了基于单次曝光光场成像的导向滤波全焦图像重建技术:结合光场成像采集视场信息,并采用光场重建的方式获取多聚焦图像源集,利用导向滤波的方法确定各级图像融合权重,进行图像融合得到大景深的全焦图像.实验证明,提出的基于单次曝光光场成像的导向滤波全焦图像重建技术不仅有效保证了多聚焦图像背景...     

Multi-focus image fusion based on window empirical mode decomposition

In order to improve multi-focus image fusion quality, a novel fusion algorithm based on window empirical mode decomposition (WEMD) is proposed. This WEMD is an improved form of bidimensional empirical mode decomposition (BEMD), due to its decomposition process using the adding window principle, effectively resolving the signal concealment problem. We used WEMD for multi-focus image fusion, and formulated different fusion rules for bidimensional intrinsic mode function (BIMF) components and the residue component. For fusion of the BIMF components, the concept of the Sum-modified-Laplacian was used and a scheme based on the visual feature contrast adopted; when choosing the residue coefficients, a pixel value based on the local visibility was selected. We carried out four groups of multi-focus image fusion experiments and compared objective evaluation criteria with other three fusion methods. The experimental results show that the proposed fusion approach is effective and performs better at fusing multi-focus images than some traditional methods.     

具有紧支撑正交非张量积小波的图像融合

提出了基于一种新的小波——具有紧支撑、正交性、伸缩矩阵为[^2 0 ^0 2]的非张量积小波的图像融合方法。首先根据非张量积小波理论,利用Daubechies构造的单变量滤波器构造出基于四通道的不可分的小波滤波器组,用此滤波器组对参加融合的图像进行分解,然后对低频部分采用取均值、高频部分采用系数绝对值取大的融合算法对分解子图进行融合,最后重构。并采用熵、交叉熵、互信息、均方根误差和峰值信噪比等指标对该方法进行了客观评价。对可见光图像与红外图像、远红外图像与近红外图像、遥感图像、多聚焦图像和其它多类图像的融合实验结果证明本方法有较好的融合效果,其融合性能与采用同样融合算法的张量积db2小波的融合方法的融合性能相当。     

Detection of infrared small target based on fusion of multi-filters北大核心CSCD

Aiming at solving accuracy problem of infrared small target detection in sky and ocean background scenarios of infrared image sequences, a novel infrared small target detection based on multi-filters algorithm fusion method is presented in this paper. Firstly infrared small target and imaging, time and space characteristics of the corresponding background noise are analyzed. Tophat algorithm with improved Robinson guard filter are then integrated to highlight target and suppress clutter background by using infrared small target imaging features. Adaptive threshold segmentation is used to extract candidate targets, while Unger smoothing filter and multi-objects association filter are used to eliminate random noise and false targets in the candidate targets. Multiple experiments of infrared small target image sequences are implemented, and experimental results show that proposed method can detect infrared small targets at 99% detection rate with high reliability and good real-time performance. © 2017, Editorial Board, Journal of Applied Optics. All right reserved.     

Infrared Multispectral Imaging: Principles and Instrumentation

Abstract

A multispectral imaging spectrometer is an instrument that can simultaneously record spectral and spatial information of a samples. Chemical and physical properties of the sample can be elucidated from such images. In a multispectral imaging instrument, a camera is used to record the spatial distribution of the sample, and the spectral information is gained by scanning a dispersive device to record spectra for each image. This overview article describes operational principles and recent development of various components used in infrared multispectral imaging instruments including the electronic dispersive devices (acousto-optic tunable filter and liquid crystal tunable filter) and IR cameras (InGaAs, InSb, HgCdTe and QWIP cameras).     

多波长激光探测微小摄像头机理研究北大核心CSCD

基于激光不同波段的探测传输特点,通过分析典型微小摄像头的回波传输特性,提出了一种针对多波长激光特征检测微小摄像头的研究方案。利用几何光学和波动光学理论,分析微小摄像头结构及其反射光谱特征,计算并仿真了一定探测距离下的回波光场,在此基础上搭建多波长激光检测系统。实验结果表明,在一定的景深范围内,具有红外截止滤光片的微小摄像头对可见光的回波光斑衍射环特征明显、条纹对比度高且可探测距离远;近红外波段的目标回波功率低、后向散射干扰严重,可探测距离近;短波红外波段几乎不受红外截止滤光片影响,且1550 nm处于人眼安全波段。实验结果与数值分析、理论仿真结果一致,验证了短波红外激光用于探测微小摄像头的可行性。     

多量级多向梯度海空复杂背景红外弱点目标检测

由于红外图像一般带有较大的噪声，采用传统的目标检测方法效果不理想。本文提出了一种新的海空背景下受强杂波和噪声污染的红外图像弱点目标检测算法。用多个量级梯度对图像目标进行检测，并对检测的结果进行了表决融合。结果表明，基于表决融合的多量级多向梯度检测消除了云层、海浪和海天线等背景干扰，在实现高检测概率的同时，不仅可以达到较低的虚警概率，而且可检测信杂比为1的点目标。     

Nonuniformity correction algorithm based on adaptive filter for infrared focal plane arrays

Response nonuniformity is a key problem that influences the imaging performance of infrared focal plane arrays (IRFPA) imaging system. A parallel processing algorithm to adaptively estimate the nonuniformity correction (NUC) parameters for IRFPA is presented. In this algorithm, a bank of the adaptive filter is applied to adaptively estimate the NUC parameters for every detector in IRFPA. The infrared image sequences are input into the bank of adaptive filter. After certain times recursion calculations are executed frame-by-frame, then the optimal coefficients of the gain and the offset of detector in IRFPA are achieved. Then the NUC is fulfilled ultimately. The algorithm reduces the influence that the response drift with time imposed on NUC effectively, and achieves good NUC effect. It was validated by real experimental imaging procedures.     

Noise characteristics analysis of short wave infrared InGaAs focal plane arrays

The increasing application of InGaAs short wave infrared (SWIR) focal plane arrays (FPAs) in low light level imaging requires ultra-low noise FPAs. This paper presents the theoretical analysis of FPA noise, and point out that both dark current and detector capacitance strongly affect the FPA noise. The impact of dark current and detector capacitance on FPA noise is compared in different situations. In order to obtain low noise performance FPAs, the demand for reducing detector capacitance is higher especially when pixel pitch is smaller, integration time is shorter, and integration capacitance is larger. Several InGaAs FPAs were measured and analyzed, the experiments’ results could be well fitted to the calculated results. The study found that the major contributor of FPA noise is coupled noise with shorter integration time. The influence of detector capacitance on FPA noise is more significant than that of dark current. To investigate the effect of detector performance on FPA noise, two kinds of photodiodes with different concentration of the absorption layer were fabricated. The detectors’ performance and noise characteristics were measured and analyzed, the results are consistent with that of theoretical analysis.