Computer Simulation of Compensation Method for Infrared Focal Plane Array

A major motivation for this work is to investigate a method of computer simulation for compensating fixed pattern noise of the infrared focal plane arrays. A mathematical model of the output signal of focal plane array was established; a compensating algorithm utilizing reference source was derived and simulating programs were designed. The images of compensating process verify the influence of nonuniformity of responsibility and offset on fixed pattern noise. The result show that simulating method of investigating compensation technology for focal plane arrays is feasible, the generated images and methods can be used to the study of image recognition.

A monolithic integrated medium wave Mercury Cadmium Telluride polarimetric focal plane array

A medium wave(MW)640×512(25μm)Mercury Cadmium Telluride(HgCdTe)polarimetric focal plane array(FPA)was demonstrated.The micro-polarizer array(MPA)has been carefully designed in terms of line grating structure optimization and crosstalk suppression.A monolithic fabrication process with low damage was explored,which was verified to be compatible well with HgCdTe devices.After monolithic integration of MPA,NETD<9.5 mK was still maintained.Furthermore,to figure out the underlying mechanism that dominat⁃ed the extinction ratio(ER),specialized MPA layouts were designed,and the crosstalk was experimentally vali⁃dated as the major source that impacted ER.By expanding opaque regions at pixel edges to 4μm,crosstalk rates from adjacent pixels could be effectively reduced to approximately 2%,and promising ERs ranging from 17.32 to 27.41 were implemented.

Testing System Based on Virtual Instrument for Readout Circuit of Infrared Focal Plane Array

Readout integrated circuit(ROIC) is one of the most important components for hybrid-integrated infrared focal plane array(IRFPA). And it should be tested to ensure the product yield before bonding. This paper presents an on-wafer testing system based on Labview for ROIC of IRFPA. The quantitative measurement can be conducted after determining whether there is row crosstalk or not in this system. This low-cost system has the benefits of easy expansion, upgrading, and flexibility, and it has been employed in the testing of several kinds of IRFPA ROICs to measure the parameters of saturated output voltage, non-uniformity, dark noise and dynamic range, etc.

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 5.89×10^10cm·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.

Thermal and mechanical characterizations of a substrate-free focal plane array

We propose a substrate-free focal plane array （FPA） and the microcantilevers extend from a supporting frame. in this paper. The solid substrate is completely removed, Using finite element analysis, the thermal and mechanical characterizations of the substrate-free FPA are presented. Because of the large decrease in thermal conductance, the supporting frame is temperature dependent, which brings out a unique feature： the lower the thermal conductance of the supporting frame is, the higher the energy conversion efficiency in the substrate-free FPA will be. The results from the finite element analyses are consistent with our measurements： two types of substrate-free FPAs with pixel sizes of 200×200 and 60×60 um^2 are implemented in the proposed infrared detector. The noise equivalent temperature difference （NETD） values are experimentally measured to be 520 and 300 mK respectively. Further refinements are considered in various aspects, and the substrate-free FPA with a pixel size of 30×30 um^2 has a potential of achieving an NETD value of 10 mK.

Growth and fabrication of a mid-wavelength infrared focal plane array based on type-II InAs/GaSb superlattices

We present the fabrication of a mid-wavelength infrared focal plane array （FPA） based on type-II InAs/GaSb strain layer superlattices （SLs）. The detectors contain a 400-period 8 ML InAs/8 ML GaSb SL active layer, which is grown by solid source molecular beam epitaxy on GaSb （100） N type substrates. Lattice mismatch between the superlattices and GaSb substrate achieves 148.9 ppm. The full width at half maximum of the first or- der satellite peak from X-ray diffraction was 28 arcsec. Single element detectors and FPA with a 128 x 128 pixels were fabricated using citric acid based solution wet chemical etching. Chemical and physical passivation effectively reduces the surface leakage and this process was characterized by I-V measurement. The devices showed a 50% cut-off wavelength of 4.73 μm at 77 K. The photodiode exhibited an RoA of 103 f2. cm2. The FPA was characterized with an integration time of 0.5 ms and F/2.0 optics at 77 K and the average blackbody detectivity of the detectors is 2.01 × 10^9 cm.Hz^1/2/W.

A substrate-free optical readout focal plane array with a heat sink structure

A substrate-ffee optical readout focal plane array （FPA） operating in 8-12 um with a heat sink structure （HSS） was fabricated and its performance was tested. The temperature distribution of the FPA with an HSS investigated by using a commercial FLIR IR camera shows excellent uniformity. The thermal cross-talk effect existing in traditional substrate-free FPAs was eliminated effectively. The heat sink is fabricated successfully by electroplating copper, which provides high thermal capacity and high thermal conductivity, on the frame of substrate-free FPA. The FPA was tested in the optical-readout system, the results show that the response and NETD are 13.6 grey/K （F / # = 0.8） and 588 inK, respectively.

TEC Colling Shortwave Infrared 320×256 Focal Plane Detector

The short-wave HgCdTe thin film material was grown by liquid phase epitaxy on CdTe substrate,Adopt n on p injection bonding and function and flip-flop mixing process,With a low noise readout circuit,sealed with a high airtightness cellular-metal shell,Using a four-stage Thermo Electric Cooler(TEC),320×256 Short Wave Infrared Focal Plane Cooling Detecto r available to operate at near room temperature(210K).Its main photoelectric performance are signal-to-noise ratio greater than 400,nonuniformity equivalent to 4.69%,operability equivalent to 99.76%,frame rate equivalent to 115Hz,component weight less than 150grams.

Progress in quantum well and quantum cascade infrared photodetectors in SITP

This paper presents a review of recent advances in quantum well and quantum cascade infrared photodetectors developed in Shanghai Institute of Technical Physics, Chinese Academy of Sciences(SITP/CAS). Firstly, the temperature-and bias-dependent photocurrent spectra of very long wavelength(VLW) GaAs/AlGaAs quantum well infrared photodetectors(QWIPs) are studied using spectroscopic measurements and corresponding theoretical calculations in detail. We confirm that the first excited state, which belongs to the quasi-bound state, can be converted into a quasi-continuum state induced by bias and temperature. Aided by band structure calculations, we propose a model of the double excited states that determine the working mechanism in VLW QWIPs. Secondly, we present an overview of a VLW QWIP focal plane array(FPA)with 320×256 pixels based on the bound to quasi-bound(BTQB) design. The technology of the manufacturing FPA based on the QWIP structures has been demonstrated. At the operating temperature of 45 K, the detectivity of QWIP FPA is larger than 1.4×10^(10) cm·Hz^(1/2)/W with a cutoff wavelength larger than 16 μm. Finally, to meet the needs of space applications, we proposed a new long wavelength quantum cascade detector with a broadband detection ranging from 7.6 μm to 10.4 μm. With a pair of identical coupled quantum wells separated by a thin barrier, acting as absorption regions, the relative linewidth(?E/E) of response can be dramatically broadened to 30.7%. It is shown that the spectral shape and linewidth can be tuned by the thickness of the thin barrier, while it is insensitive to the working temperature. The device can work above liquid nitrogen temperature with a peak responsivity of 63 mA/W and Johnson noise limited detectivity of 5.1×10~9 cm·Hz^(1/2)/W.

128×128 element PtSi infrared CCD image sensor

A new 128×128 element PtSi Schottky barrier infrared image sensor with ITCCD readout structure and PtSi thin film optical cavity detector structure has been fabricated,which has 50μm×50 μm pixels,a fill factor of 40 percent,the nonuniformity of 5% or less and the dynamic range of over or equal to 50 dB.The noise equivalent temperature difference is 0.2 K with f/1.0 optics at 300 K background. In this paper,the principle of operation,design consideration and fabrication technology for the device are described.

中波红外640×512(25μm)探测器组件可靠性验证试验

随着红外探测器技术的发展,对探测器组件的可靠性提出了更高的要求。探测器可靠性随整机考核的方法难以满足考核需求,针对该问题,开展了中波红外640×512(25μm)探测器组件在环境应力下的可靠性验证研究,对探测器组件中的关键部位进行了高温加速寿命试验、持续工作等试验,并根据关键部件专项可靠性试验数据对探测器组件的整体可靠性进行预计,结合所选择的可靠性评估方法,对试验结果进行评估,评估结果表明所研制的组件满足可靠性要求。所使用的可靠性验证及评估方法,可以对制冷型红外探测器组件做出较为客观、准确的评估。

倒装焊接机调平问题的研究

倒装互连工艺是制冷型红外焦平面探测器制备的关键技术之一,Z向压偏问题是影响倒装互连工艺成品率的重要因素。从倒装焊接机的设备角度,讨论了倒装焊接机调平与Z向压偏问题的关联性。测量的校准块不同位置焦距数值、标定校准块中点的准直十字位置粗略表明上焊臂与下基台的相对平行。此外,采用激光束获取的上下两个标准块不同位置与激光器的距离,精确表明上焊臂与下基台的空间平行,验证了倒装焊接机调平的准确度。首次建立研究倒装焊接机调平问题的方法体系,为高效解决倒装互连工艺Z向压偏问题、提升红外焦平面探测器成品率和可靠性打下了良好基础。

冷屏对红外焦平面探测器组件性能的影响

分析了国内早期中波320×256红外焦平面探测器组件与国外同类产品在装机性能上的差异,采用三种实验方法检测了国内外探测器组件的光电性能,通过对探测器组件光电转换和结构的分析,确定出杂散光在冷屏内部的反射是导致测试结果差异的原因,冷屏内表面黑化层和结构形式是影响组件实际应用的关键。冷屏结构改进后,有效改善了国内探测器组件的实际应用性能。

InGaAs短波红外探测器研究进展

InxGa1-xAs材料属于Ⅲ-Ⅴ族化合物半导体合金材料,随In组分含量的不同,其光谱响应的截止波长可在0.87～3.5μm范围内变化,并具有高量子效率,加之成熟的MBE和MOVCD材料生长方式,很容易获得大面积高质量的外延材料,InGaAs材料因此成为一种重要的短波红外探测材料。InGaAs探测器可以在室温或近室温下工作,且具有较高的灵敏度和探测率,是小型化、低成本和高可靠性的短波红外探测系统的最佳选择,因此InGaAs短波红外探测器获得了飞速的发展和广泛的应用。同时对国内外InGaAs焦平面探测器发展状况和趋势进行了介绍。

国外非制冷红外焦平面阵列探测器进展

非制冷红外焦平面阵列探测器是目前发展最为迅速的红外探测器种类之一,并已广泛渗透到军事和民事应用中。本文重点阐述几种国外具有代表性的非制冷红外焦平面探测器的现状及其发展趋势。

大视场激光探测与告警技术

利用四路红外非制冷焦平面探测器、大视场光学系统、窄带滤光片和信号处理系统,构成了凝视成像激光探测与告警系统.光学系统采用三片式结构的广角镜头来实现大视场;使用先进的非球面光学设计技术,并以FPGA完成探测器响应信号的非均匀校正,以改善像质;通过光学系统的畸变校正,提高激光的探测方向精度;利用激光和背景强度之间的反差,通过激光目标检测算法进行告警.实验表明,该系统能在127°视场范围内对波长为1.315μm, 2.7μm, 3.8μm, 10.6μm的4种激光进行告警,探测功率密度范围为0.05～50mW/cm2,探测方向精度可达1°.

InAs/GaAsSb带间级联中波红外焦平面研究

针对高工作温度红外探测器的迫切需求,设计并利用分子束外延技术制备了高晶格质量的2级带间级联中波红外探测材料,带间级联单元器件在最高323 K下可以测试到清晰的响应光谱,140 K下暗电流密度达到4×10^-5A/cm^-2.并在此基础上利用干法刻蚀技术实现了320×256规模的台面型带间级联红外焦平面原型器件.焦平面测试结果表明其在80-120K范围内量子效率达到30%,127 K下噪声等效温差为55.1 mK,盲元率为2.3%.采用该焦平面器件在127 K下获得了较为清晰的演示性室温目标红外热成像.

红外成像制导技术发展现状与展望

随着信号处理、半导体技术的飞速发展,近几年红外成像制导技术取得了长足的进展。为了对该领域相关技术进行总结,为未来的研究工作提供参考,首先介绍了红外成像制导技术的概念,分析了红外光学系统、红外焦平面探测器以及图像处理等红外成像制导中的关键技术的发展现状。参考国内外红外成像制导领域的发展趋势,结合作者多年从事可见光、红外成像制导技术研究积累的经验以及对该领域关键技术的理解,预测了未来红外成像制导技术的发展方向。

红外焦平面阵列探测器盲元检测算法研究

受材料、制造工艺等因素的影响,红外焦平面阵列探测器均存在一定数量的盲元。在分析探测单元响应特性的基础上,提出一新的盲元检测算法。通过调节探测单元响应的显示动态范围,利用设定阈值完成盲元检测。实验表明,算法不受盲元簇大小的影响,查找速度快、定位准确率高,有效提高了图像质量。

红外探测器发展需求

由于未来作战环境复杂,红外探测技术发展面临严峻挑战,而作为红外型武器的核心——红外探测器,正朝着高灵敏、宽谱段、高分辨率、低功耗、小型化和智能化的方向发展。通过回顾相关产业军民两用融合情况和红外探测技术发展历程,总结军事发展对探测器新的要求,以确立新一代探测器发展方向。在详细分析国外红外探测器发展历程和现状的基础上,重点介绍了国外红外焦平面探测器的最新研制情况和成果,包括非制冷红外探测器、制冷型红外探测器、红外双色探测器等,并总结强调第三代红外探测器需要在控制成本的同时不断提高和改进红外焦平面探测系统的性能。最后概述了智能化红外焦平面阵列的发展情况。