双材料微梁阵列室温物体红外成像

针对近年出现的新概念光学读出双材料微梁阵列红外成像技术，提出了具有热变形放大效果的无硅基底回折腿间隔镀金的微梁单元结构,并建立了其热机械模型，在模型分析基础上，成功的设计制作了100×100像素的焦平面阵列(focal plane array,FPA).在构建的红外成像系统中，实现了对室温物体——人体的热成像，噪声等效温度差约为200mK.实验结果与热机械模型的分析一致. 关键词： 非制冷红外成像 光学读出 双材料微梁阵列     

Pixels array matching for optical readout microcantilever array sensing system

An approach based on pixels array matching is proposed for optical readout bimaterial microcantilever focal plane array (FPA) sensing system, by which the CCD's pixel array can match the low resolution FPA properly. Compared with the old method, it has the following three advantages: (1) reduces the impact on the infrared imaging quality due to the bending deformation of the microcantilever pixels; (2) decreases the background noise and lower the infrared imaging system's noise equivalent temperature difference; (3) increases the imaging system's frame rate. A microcantilever FPA infrared imaging system with a programmable smart camera was developed to demonstrate the effectiveness of the approach. In addition, the approach can be applied to a similar optical readout micro-array sensing system whose resolution is lower than the CCD.     

基于无基底焦平面阵列红外热像仪的理论模型分析

基于双材料微悬臂梁热变形原理的光学读出非制冷红外探测阵列经历了从有基底结构向无基底结构的发展过渡,无基底阵列的红外成像结果和有限元模型分析均表明无基底阵列不满足恒温基底条件.本文结合电学比拟的方法,提出了一种新的基于无基底焦平面阵列(focal plane Array,FPA)的热传递分析的理论模型.分析采用整体考虑的思路,避开了无基底FPA阵列各单元热传递互相影响所产生的复杂热分布分析,并考虑了框架对热量的吸收与传递.理论模型采用外边框与环境等温的边界条件,虽不及有限元方法对边界条件的处理灵活,但也已取 关键词： 光学读出 无基底 非制冷红外成像 焦平面阵列     

两轴周视光电跟踪天际线焦平面像的解析表达

鉴于动基座周视光电跟踪系统的基座俯仰和横滚角会造成天际线在红外焦平面阵列上所成的像不再与反射镜面俯仰轴在焦平面阵列上的投影平行,建立了动基座两轴周视光电跟踪系统的五自由度数学模型。重构了包含目标信息的天际平面在大地坐标系下的方程,推导得出了天际线在焦平面阵列上成像的解析表达式,并将其与反射镜面俯仰轴在焦平面阵列上的投影表达式进行了对比。天际线焦平面阵列成像的解析表达式可为目标可测、天际线不可测情况下,沿像的方向向量及其正交方向进行方位、俯仰补偿及目标方位解算提供理论前提。     

红外CCD焦平面阵列的军用前景

评述近几年红外CCD焦平面阵列的进展情况及发展水平。简要介绍CCD焦平面阵列在导弹寻的头和瞄准具等方面的军用现状,并展望未来的发展趋势。     

320×240长波非致冷微测辐射热计红外热象仪的研制

介绍了基于微测辐射热计320×240长波非致冷红外热象仪的研制,详细说明了其电气系统的设计方法及技术关键,并对其光学系统进行了简要说明.采用高象质的双反射光学系统以减少象差;红外探测器采用320×240长波非致冷集成微测辐射热计红外焦平面阵列(FPA);电气系统采用复杂可编程逻辑器件(CPLD)完成红外焦平面阵列的驱动,应用数字信号处理(DSP)技术实现红外焦平面阵列的非均匀性校正、图象增强及红外图象实时显示等.     

Diffractive Microlens Array Monolithic Integration with PtSi Focal Plane array

Diffractive microlens arrays can completely collect the light at the focal plane and concentrate it into a smaller spot size on the detector plane, the photodetector area can be substantially reduced. Increased gamma radiation hardening and noise reduction result from the decrease in photodetector sensitive area. The diffractive microlens arrays have been designed by considering the correlative optical and processing parameters for PtSi focal plane array. They have been fabricated on the backside of PtSi focal plane array chip by successive photolithography and Ar⁺ ion-beam-etching technique. The alignment of microlens array with PtSi focal plane array was completed by a backside aligner with IR light source. The practical processes and fabrication method are discussed. The performance parameters of PtSi FPA with diffractive microlens array are presented.     

红外焦平面阵列非线性校正曲线测量方法

针对红外焦平面阵列强度响应的非线性失真现象,本文提出了一种基于单波长激光器测定红外焦平面阵列非线性校正曲线的方法,设计出用于测量的实验装置,并通过实验研究获得了实测的非线性校正曲线。结果表明,该方法规避了红外焦平面阵列光谱响应不均匀性的影响,满足了装置器件在工程技术中通用性和实用性的需要,在简单易行的同时保证了较高的测量精度。     

凝视焦平面探测器的空间采样效应建模仿真

为了增加红外凝视焦平面阵列探测器成像仿真的置信度,对探测器所存在的空间采样效应产生机理进行了分析,并且从空间域角度对其进行了建模,借助于基于图像像素处理的方法进行实验仿真;为了客观地评价空间采样效应对探测器成像质量的影响,定义了图像的负指数型平滑度,实验结果表明,叠加空间采样效应后探测器输出图像的平滑度减小了11.7%,图像局部波动变大,从而验证了红外探测器成像仿真中空间采样效应考虑的必要性。     

场景自适应的红外焦平面成像动态范围调整技术

针对红外焦平面对辐射强度较大的目标输出动态范围不足的问题,提出了一种场景自适应的红外焦平面成像动态范围调整技术。包括3个方面的内容:从图像中提取目标灰度特征,获取动态范围自适应依据;结合最小均方自适应滤波算法,对调整依据进行滤波预测后给出调节值;把灰度调节值转换成电平值,利用电平值设置红外焦平面偏置电压完成焦平面成像动态范围自适应。最后,对整体方案进行了实验验证。通过在红外焦平面成像系统中实验证明了基于场景成像动态范围自适应方法的可行性,并获得了很好的效果,成像质量有明显提高。     

场景自适应的红外焦平面成像动态范围调整技术

针对红外焦平面对辐射强度较大的目标输出动态范围不足的问题,提出了一种场景自适应的红外焦平面成像动态范围调整技术。包括3个方面的内容：从图像中提取目标灰度特征,获取动态范围自适应依据;结合最小均方自适应滤波算法,对调整依据进行滤波预测后给出调节值;把灰度调节值转换成电平值,利用电平值设置红外焦平面偏置电压完成焦平面成像动态范围自适应。最后,对整体方案进行了实验验证。通过在红外焦平面成像系统中实验证明了基于场景成像动态范围自适应方法的可行性,并获得了很好的效果,成像质量有明显提高。     

单片式非本征硅红外焦平面阵列

介绍典型单片式非本征硅红外焦平面阵列的结构及性能参数。     

Parallel asynchronous focal plane array processing

A new approach to focal plane processing based on silicon injection mode devices is suggested. These devices provide a natural basis for parallel asynchronous focal plane image preprocessing. The simplicity and novel properties of the devices would permit an independent analog processing channel to be dedicated to every pixel. A laminar architecture built from arrays of the devices would form a two-dimensional (2-D) array processor with a 2-D array of inputs located directly behind the focal plane detector array. A 2-D image data stream would propagate in neuronlike asynchronous pulse coded form through the laminar processor. No multiplexing, digitization or serial processing would occur in the preprocessing stage. High performance is expected because approximately linear pulse coding has already been observed for input currents ranging over six orders of magnitude down to one picoampere with noise referred to input of about 10 femtoamperes. Very low power requirements suggest utility in space and in conjunction with very large arrays. Multispectral processing is possible because of compatibility with the cryogenic environment of high performance infrared detectors.     

640 × 512 pixel narrow-band, four-band, and broad-band quantum well infrared photodetector focal plane arrays

A 9 μm cutoff 640 × 512 pixel hand-held quantum well infrared photodetector (QWIP) camera has been demonstrated with excellent imagery. A noise equivalent differential temperature (NEDT) of 10.6 mK is expected at a 65 K operating temperature with f/2 optics at a 300 K background. This focal plane array has shown background limited performance at a 72 K operating temperature with the same optics and background conditions. In this paper, we discuss the development of this very sensitive long-wavelength infrared camera based on a GaAs/AlGaAs QWIP focal plane array and its performance in quantum efficiency, NEDT, uniformity, and operability. In the second section of this paper, we discuss the first demonstration of a monolithic spatially separated four-band 640 × 512 pixel QWIP focal plane array and its performance. The four spectral bands cover 4–5.5, 8.5–10, 10–12, and 13.5–15 μm spectral regions with 640 × 128 pixels in each band. In the last section, we discuss the array performance of a 640 × 512 pixel broad-band (10–16 μm full-width at half-maximum) QWIP focal plane.     

Ultrathin Planar Microlens Arrays Based on Geometric Metasurface

Ascribing to the properties of two dimensional parallel focusing and imaging, low propagation loss, integration and miniaturization, microlens array has been widely used in imaging, optical communication, organic light emitting devices, adaptive optics, photolithography, biomedical and other applications. However, the existing traditional microlens array suffers from difficulty in fabrication, large‐thickness, curved surface, non‐uniformity of light spots, or requirement of additional discrete components to control the microlens. Herein, a planar microlens array is experimentally demonstrated based on the geometric metasurface. The single microlens is composed of space‐variant subwavelength metallic gratings with high polarization conversion efficiency and thus exhibits gradient phase distribution. The focused spot diameter of 22.5 μm with radius of 350 μm, focal length of 1 cm and the light spots intensity uniformity of 0.9885 (standard deviation 0.0115) at the focal plane are obtained. Moreover, the broadband property of microlens array is also confirmed. The novel design strategy for microlens array would facilitate the miniaturization of optical devices and be easily integrated in the optical interconnected devices.     

Waveguide Array Wavelength Router Design to Improve Insertion Loss Uniformity

We propose a wavelength router design to improve insertion loss uniformity. Branched waveguides are placed at junctions between the waveguide array and a planar waveguide. The diffracted light injected into planar waveguides is forwarded in different directions. At the image plane of the planar waveguide, a flat top envelope is attained to ensure loss uniformity among output ports.     

Very long wavelength infrared focal plane arrays with 50% cutoff wavelength based on type-Ⅱ In As/GaSb superlattice

A very long wavelength infrared(VLWIR) focal plane array based on In As/Ga Sb type-Ⅱ super-lattices is demonstrated on a Ga Sb substrate. A hetero-structure photodiode was grown with a 50% cut-off wavelength of 15.2 μm, at 77 K.A 320×256 VLWIR focal plane array with this design was fabricated and characterized. The peak quantum efficiency without an antireflective coating was 25.74% at the reverse bias voltage of-20 mV, yielding a peak specific detectivity of 5.89×1010cm·Hz~(1/2)·W~(-1). The operability and the uniformity of response were 89% and 83.17%. The noise-equivalent temperature difference at 65 K exhibited a minimum at 21.4 mK, corresponding to an average value of 56.3 mK.     

A prototype for high resolution infrared reflectography of paintings

A new scanner for infrared reflectography of ancient paintings is described. The system is based on an InGaAs focal plane array which automatically scans the image plane of a lens for wide format photography. The device is compact, portable and fast for use in situ.     

光学读出红外成像中面光源影响下的光学检测灵敏度研究

在光学读出红外成像的理论分析中, 通常将具有一定实际尺寸的非相干面光源简化为理想点光源, 导致了分析误差. 本文建立了面光源模型, 通过夫琅禾费衍射理论, 研究了面光源影响下的光学检测灵敏度, 发现了光学检测灵敏度随光源半径和焦平面阵列反光板长度的变化关系, 提出了面光源影响下的光源尺寸和反光板长度的优化设计准则. 针对理论分析, 进行了实验验证, 测试结果与理论分析一致. 关键词： 面光源 光学读出 焦平面阵列 非制冷红外成像     

积分球辐射光源照度均匀性研究

针对CCD等焦面阵列光电器件常被置于积分球辐射光源出口平面进行测试的误区,研究了积分球辐射光源照度分布的均匀性,得到了合理使用积分球光源测试光电器件的依据。基于数值解析方法和蒙特卡罗方法,建立了理想积分球辐射光源照度均匀性数学模型和非理想积分球辐射光源照度均匀性仿真模型,分析了与积分球光源出口不同距离处光电器件受光面上照度分布情况,并实验测试了两套积分球辐射光源照度分布情况,得到了与积分球辐射光源不同距离处光电器件受光面上照度均匀性分布规律。研究表明:当光电器件受光面直径小于积分球光源出口直径一半、光电器件和积分球出口之间的距离与积分球出口直径的比值在3至5之间时,可在光电器件受光面上获得均匀性优于99%的照度场。