红外焦平面探测器的读出电路

红外焦平面阵列是现代红外成像系统的关键元件 ,不论是混合式还是单片式红外焦平面阵列 ,都采用读出电路来实现信号的多路传输以减少阵列输出信号线的数目。论述了读出电路在焦平面信号传输中的作用 ;讨论了用于实现红外焦平面阵列读出电路的一些实施技术 ;提出了红外焦平面阵列读出电路今后的研究方向     

Design of midwave infrared athermalization optical system with a large focal plane array

Based on the most advanced staring focal plane array which had a format of 640 × 480 and the pixel pitch of 15 μm, a set of all-sphere midwave infrared ahermalization optical system was designed. The working wavelength was in 3–5 μm, the full field of view was 8.58°, the relative aperture was 1/2, the efficient focal length (EFL) was 80 m. The opticalsystem consisted of four lenses with three kinds of material – Ge, ZnSe and Si. All surfaces were sphere, which was easier to process test, making the cost inexpensive, and it could avoid using diffractive surface and aspheric surface. The image quality of the system approaches the diffraction limit in the temperature range −60 °C-180 °C. The design results proved that, the high resolution midwave infrared optical system had compact structure, small volume, high resolution and excellent image quality, meeting the design requirements, so that it could be used for photoelectric detection and tracking system.     

一种新的红外焦平面阵列非均匀性代数校正算法

 针对传统红外图像非均匀性代数校正算法收敛速度慢、运动估计精度不高的缺点,提出一种多尺度光流帧间运动估计的非均匀代数校正算法。通过时域低通滤波,采用多尺度光流估计下一帧图像,将所得图像对进行代数校正。该方法性能在自主研发的热像仪中得到验证,和传统的红外图像非均匀性代数校正算法相比,算法收敛速度从60帧提高到25帧,提高一倍左右,运动估计精度从校正后图像方差76.539减少到32.482。     

Time-resolved infrared spectrometry with a focal plane array and a galvano-mirror

Time-resolved spectrometry was conducted in the mid-infrared region (2.8-4.6 microm). A galvano-mirror causes a spectrally dispersed beam to repeatedly sweep up and down a PtSi focal plane array so that each element of the array is struck by the beam only once at some point within a time frame. Transient spectra of flowing gases (hydrocarbon and carbon dioxide) were measured at 80 micros intervals.     

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。     

无基底焦平面阵列的红外成像性能分析

利用提出的光学读出非制冷红外成像系统,先后制作了单元尺寸各不相同的单层膜无基底焦平面阵列(focal plane array,FPA),获得了室温物体的热图像.分析发现,当FPA的单元尺寸从200μm逐渐减小到60μm时,基于恒温基底模型的理论响应与实验结果的偏差逐渐增大.通过有限元分析方法,模拟分析了不同尺寸的微梁单元在无基底FPA中的热学行为,发现了当单元尺寸逐渐减小时恒温基底模型偏差逐渐增大的原因,即无基底FPA的支撑框架不满足恒温基底条件,受热辐射后支撑框架的温升从基底上抬高了单元的温升.论文还分 关键词： 光学读出 非制冷红外成像 焦平面阵列 无基底     

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。     

Crosstalk suppressing design of GaAs microlenses integrated on HgCdTe infrared focal plane array

In this study, crosstalk suppressing design of dielectric GaAs microlenses integrated on a traditional HgCdTe infrared focal plane array is presented, by exploiting the finite difference time domain technique. Responsive photocurrent of the objective pixel and crosstalk between adjacent detectors have been numerically simulated, using commercial TCAD software Apsys, for a mid-wavelength planar array with a pitch of 20 $\upmu $ m. By properly adjusting both the microlens radius and the absorber thickness, crosstalk can be notably suppressed to less than 1 % while the photoresponse is maintained or even enhanced.     

制冷红外焦平面和热像仪的性能评价与验收

在对进口的制冷红外焦平面和红外热像仪进行性能评价与验收中,针对存在的问题,提出了一种新的基于制冷红外焦平面工作温度的简单易行的评价方法。通过测试制冷红外热像仪的两个关键指标,即制冷时间和探测器的工作温度,可以判断制冷红外热像仪是否合格,解决了在制冷红外热像仪验收过程中出现的问题。     

Non-uniformity correction of infrared focal plane array in point target surveillance systems

We discuss the influence of non-uniformity and non-uniformity correction on point target detection in infrared surveillance system, and propose a non-uniformity correction approach which is based on signal intensity and sensor characteristics. Theoretical models are used to derive the combined effect of background clutter, sensor random noise, target, non-uniformity and correction error on the signal-to-noise-and-clutter ratio. From our analysis, it can be noted that background clutter intensity is successively modulated by sensor non-uniformity and non-uniformity correction, while sensor random noise is modulated by the non-uniformity correction process only. Furthermore, background clutter and sensor random noise are the key factors that affect the performance of a surveillance system, when it is used to detect point targets. The method presented in this paper takes all of the above into account, moreover, it considers the difference between scanning and staring focal plane array. The experimental results demonstrate the effectiveness of the proposed method.     

Photon trapping photodiode design in HgCdTe mid-wavelength infrared focal plane array detectors

Photon trapping photodiode design in HgCdTe mid-wavelength infrared focal plane array detectors is investigated in this work, utilizing the finite-difference time-domain technique. The quantum efficiency and the current–voltage characteristics have been numerically simulated, using Crosslight Technology Computer Aided Design software. Simulation results indicate that dark current is reduced more significantly in the photon trapping photodiode than in the mesa photodiode while maintaining the same quantum efficiency.     

A low cost uncooled focal plane array test system

The commercial test equipments from Pulse Instruments, Lumitron and Electro Optical Industries Inc. are very expensive. So, we proposed a new method of very low cost test system for testing the non-uniformity and signal/noise (S/N) and other characteristics of the uncooled focal plane array (UFPA). It uses complex programmable logic device to generate the necessary pulse for the UFPA and the low noise low dropout micropower regulator to obtain the low noise bias. A proportional-integral-differential controlled thermal electrical cooler based on micro-processor unit stabilizes the UFPA. The National Instruments 6111E Data Acquisition Card is used to convert the analog output of UFPA into digital signal into computer. Its 12-bits conversion capability provides sufficient accuracy for evaluating the S/N ratio and non-uniformity of 128×128 pixels UFPA. Labview is used to analyze the signal. The instrument is fast and convenient to adapt the system to other types of UFPA. Further discussion is presented to determine factors that affect the accuracy of the tester.     

A super-pixel QWIP focal plane array for imaging multiple waveband temperature sensor

The multi-waveband temperature sensor (MWTS) array, in which each super-pixel (2 × 2 pixel cell) operates at four distinct thermal infrared (IR) wavebands is being developed. Using this high spatial resolution, four-band thermal IR band detector array, accurate temperature measurements on the surface of an object can be made without prior knowledge of its exact emissivity. This multi-band detector involves intersubband transition in III–V semiconductor-based quantum layered structures. Each detector stack absorbs photons within the specified wavelength band while allowing the transmission of photons in other spectral bands, thus efficiently permitting multi-band detection. This produces multiple, spectrally resolved images of the scene that are recorded simultaneously in a single snapshot on the FPA. From the multispectral images and calibration information about the system, computational algorithms are used to evaluate the temperature on the surface of a target.     

激光辐照碲镉汞红外焦平面探测器的热应力损伤研究

基于碲镉汞红外焦平面探测器的结构与其材料热力学相关特征,描述了激光辐照碲镉汞红外焦平面探测器造成的损伤机理。根据相关的辐照环境和条件,通过有限元分析法建立了三维仿真模型。基于COMSOL Multiphysics软件仿真了碲镉汞红外探测器受到波长10.6 μm的激光辐照时,探测器各部分的温度变化及应力变化情况;通过数值分析方法,比较了碲镉汞探测器在经过光斑面积相同。功率不同的激光辐照后,其表面径向及内部轴向的温度场变化及应力场变化情况。仿真结果表明:在经过106 W/cm2的连续激光辐照后碲镉汞探测器表面温度与应力快速升高,造成探测器表面损伤,同时探测器被辐照部位的温度变化也导致其内部局部应力值变化。将碲镉汞探测器的应力损伤阈值及变化趋势与文献中相关实验数据进行对比,发现二者结果基本一致,验证了模型的可行性。     

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     

一种具有自适应非均匀校正功能的非制冷焦平面探测器组件

基于场景的非均匀校正算法(scene based nonuniformity correction,SBNUC)是非均匀校正技术今后的重点发展方向,介绍了近年来基于恒定统计约束的SBNUC、神经网络的SBNUC和运动估计的SBNUC算法的研究进展。研究了SBNUC算法在实际焦平面探测器组件上的实现方法,该方法仅依赖拍摄序列的信息对焦平面探测器的增益和偏置参数进行组间更新或帧间更新,可有效补偿温漂。研制了一种具有自适应非均匀校正功能的非制冷焦平面探测器组件,红外视频经该组件处理后,图像质量有所提高。该组件可明显提高热成像系统的成像性能,并能动态地保证热成像系统随场景变化的稳定性。     

Design rule of indium bump in infrared focal plane array for longer cycling life

In light of the proposed equivalent method, a three-dimensional structural modeling of InSb infrared focal plane arrays (IRFPAs) is created, and the simulated strain distribution is identical to the deformation distribution on the top surface of InSb IRFPAs. After comparing the deformation features at different regions with the structural characteristics of IRFPAs, we infer that the flatness of InSb IRFPAs will be improved with a thinner indium bump array, and this inference is verified by subsequent simulation results. That is, when the diameter of indium bump is smaller than 20 μm, the simulated Z-components of strain on the whole top surface of InSb IRFPAs is uniform, and the deformation amplitude is small. When the diameter of indium bump is larger than 28 μm, the simulated Z-components of strain increases rapidly with the thicker indium bump, and the flatness of InSb IRFPAs is worsened rapidly. According to the changing trend of deformation amplitude with diameters of indium bump, and employing element pitches normalization method, a design rule of indium bump is proposed. That is, when the diameter of indium bump is shorter than 0.4 times the element pitch, the flatness of InSb IRFPAs is in an acceptable range. This design rule was supported by different IRFPAs with different formats delivered by several main research groups for achieving a longer cycling life.     

Guided filter and adaptive learning rate based non-uniformity correction algorithm for infrared focal plane array

Imaging non-uniformity of infrared focal plane array (IRFPA) behaves as fixed-pattern noise superimposed on the image, which affects the imaging quality of infrared system seriously. In scene-based non-uniformity correction methods, the drawbacks of ghosting artifacts and image blurring affect the sensitivity of the IRFPA imaging system seriously and decrease the image quality visibly. This paper proposes an improved neural network non-uniformity correction method with adaptive learning rate. On the one hand, using guided filter, the proposed algorithm decreases the effect of ghosting artifacts. On the other hand, due to the inappropriate learning rate is the main reason of image blurring, the proposed algorithm utilizes an adaptive learning rate with a temporal domain factor to eliminate the effect of image blurring. In short, the proposed algorithm combines the merits of the guided filter and the adaptive learning rate. Several real and simulated infrared image sequences are utilized to verify the performance of the proposed algorithm. The experiment results indicate that the proposed algorithm can not only reduce the non-uniformity with less ghosting artifacts but also overcome the problems of image blurring in static areas.     

Short-wave infrared InGaAs photodetectors and focal plane arrays

In this article, unique spectral features of short-wave infrared band of 1 μm–3 μm, and various applications related to the photodetectors and focal plane arrays in this band, are introduced briefly. In addition, the different material systems for the devices in this band are outlined. Based on the background, the development of lattice-matched and wavelengthextended InGaAs photodetectors and focal plane arrays, including our continuous efforts in this field, are reviewed. These devices are concentrated on the applications in spectral sensing and imaging, exclusive of optical fiber communication.