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.

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.

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.

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.

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.

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.

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.

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。

国外硅基UMBIRFPA制备技术研究进展

介绍了国外硅基非致冷微测辐射热计红外焦平面阵列（Ｓｉ－ＵＭＢＩＲＦＰＡ）的典型结构、制备工艺技术以及ＵＭＢＩＲＦＰＡ的性能参数。

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。

军用PtSi-SBIRFPA的新发展

概述了军用热成象系统中硅化铂肖特基势垒红外焦平面阵列（ＰｔＳｉ－ＳＢＩＲＦＰＡ）技术的新发展。

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.

New Dynamic Algorithm for IRFPA Bad Pixel Detection and Compensation Based on Statistics

Based on the analysis to the behavior of bad pixels, a statistics-based auto-detecting and compensation algorithm for bad pixels is proposed. The correcting process is divided into two stages： bad pixel detection and bad pixel compensation. The proposed detection algorithm is a combination of median filtering and statistic method. Single frame median filtering is used to locate approximate map, then statistic method and threshold value is used to get the accurate location map of bad pixels. When the bad pixel detection is done, neighboring pixel replacement algorithm is used to compensate them in real-time. The effectiveness of this approach is test- ed by applying it to I-IgCATe infrared video. Experiments on real infrared imaging sequences demonstrate that the proposed algorithm requires only a few frames to obtain high quality corrections. It is easy to combine with traditional static methods, update the pre-defined location map in real-time.

Adaptive nonuniformity correction for IRFPA sensors based on neural network framework

For infrared focal plane graded during signal acquisition array sensors, imagery is departicularly nonuniformity. In this paper, an adaptive nonuniformity correction technique is proposed which simultaneously estimates detector-level and readout- channel-level correction parameters using neural network approaches. Firstly, an improved neural network framework is designed to compute the desired output. Secondly, an adaptive learning rate rule is used in the gain and offset parameter estimation process. Experimental results show the proposed algorithm can achieve a faster convergence speed and better stability, remove nonuniformity and track parameters drift effectively, and present a good adaptability to scene changes and nonuniformity conditions.

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.

A novel MEMS-based focal plane array for infrared imaging

On the basis of opto-mechanical effect and micro electromechanical system(MEMS)technology,a novel substrate-free focal plane array(FPA)with the thermal isolated structure for uncooled infrared imaging is developed,even as alternate evaporated Au on SiN cantilever is used for thermal isolation.A human thermal image is obtained successfully by using the infrared imaging system composed of the FPA and optical detecting system.The experiment results show that the realization of thermal isolation structure in substrate-free FPA increases the temperature rise of the deflecting leg effectively,whereas the noise equivalent temperature difference(NETD)is about 200 mK.

国外凝视型舰载红外搜索与跟踪系统综述

为一种被动式告警系统,舰载红外搜索与跟踪系统(IRST)能够可探测和跟踪掠海反舰导弹和低空威胁目标,为舰船作战管理系统和指挥控制系统提供目标指示信息,在提高舰船的态势告警能力和自防御能力方面具有不可替代的优势。与传统的360°机械扫描的IRST系统相比较,新型的凝视型IRST系统使用多个基于FPA阵列凝视非转动传感器组件,增大俯仰角覆盖,具有的高数据更新率确保快速反应时间,增强了对高速低探测性目标以及非对称威胁目标的自动探测和跟踪性能。论文介绍国外新型凝视型舰载红外搜索与跟踪系统的发展现状、技术特点和应用,对重点技术进行了分析。

短波红外单光子探测器的发展(特邀)

InP/InGaAs短波红外单光子探测器(SPAD)是目前制备技术较为成熟且获得广泛应用的单光子探测器,通过半导体热电制冷(TEC)即可达到的工作温度(-40℃左右),具有体积小、成本低,方便安装和携带的应用优势;另外,基于常规半导体二极管的芯片制造工艺很容易实现大面阵单光子阵列,除了探测信号,还具备三维数字成像功能。国外包括美国、瑞士、意大利、韩国、日本等对InP/InGaAs SPAD进行了长期持续的研究,目前已研制出单管的货架产品,性能还在不断的优化和改进之中,其单光子探测器阵列呈现了清晰的三维成像效果,正在逐步应用。国内包括重庆光电技术研究所、中国科学院上海技术物理所、西南技术物理研究所、中国科学技术大学、云南大学等对InP/InGaAs SPAD芯片先后进行了器件设计和器件制备研究,目前单管的性能已经达到与国外报道相当的性能。国内单光子探测器阵列的研究获得了一定的进展,但芯片规模和器件性能有待提升。文中对国内外InP/InGaAs短波红外单光子探测器的发展,在设计和研制中存在的问题,以及近10年来的优化改进进行了介绍,重点介绍了高温、高速以及单光子焦平面阵列的发展,并结合新颖的离化工程和新的材料体系发展,分析了未来的短波红外单光子探测器的发展趋势。

锑化铟红外探测器的微透镜阵列设计及试验

台面型锑化铟红外焦平面探测器的制作工艺简单,量子效率高,但是填充因子较低且会随着像元尺寸的减小而进一步降低。减小台面腐蚀深度可以提高探测器的填充因子,但会增大串音。介绍了一种新型微透镜阵列的设计与制备方法,以提高锑化铟红外探测器的填充因子并减小串音。与现有的热回流微透镜阵列相比,该微透镜阵列的填充率、表面粗糙度以及尺寸均匀性能得到了较好的兼顾,可直接在锑化铟红外探测器表面制作,工艺简单。结果显示,探测器的串音降低26%,光响应提高22%。

一种锥形自调式J-T制冷器

介绍了一种既可以实现快速启动又能够维持长时间小流量工作的锥形自调式J-T制冷器,可以广泛应用于制导导弹中红外焦平面探测器组件的制冷。该J-T制冷器采用微型波纹管作为自调机构,具有成本低、适应范围广等特点。与探测器杜瓦组件进行耦合试验,结果表明在50 MPa氩气气源条件下,芯片降温至100 K所需时间≤5 s。