【作者】 吴健雄；

【导师】 张青川；

【作者基本信息】 中国科学技术大学 ， 固体力学， 2014， 博士

【摘要】 红外成像除了军事用途外,近些年随着非制冷红外成像技术的长足发展,已经越来越广泛的应用到诸如工业、医疗、汽车、监控等领域。在非制冷红外成像技术中,本课题组设计并实现了一种新型光学读出非制冷红外成像系统。本文在课题组研究的基础上,进行了读出光路方面的优化研究、大气环境下无基底FPA(焦平面阵列)的热机械性能研究、光读出红外图像的复原优化研究等工作。首先进行了读出光路方面的优化,发现考虑读出光路中LED(发光二极管)光源的实际尺寸时,仍将LED光源简化为理想点光源会引起较大误差。因此本文建立了面光源模型,解释了光学检测灵敏度并没有随着FPA反光板尺寸的降低而出现大幅降低的难题(理想点光源模型认为应该是线性降低)。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、反光板长度、透镜焦距、读出光源波长的优化设计准则,并进行了实验验证。详细分析了光读出中关键参数——刀口的最佳滤波位置,发现最佳滤波位置与光强的关系,并通过一系列步骤计算找到最佳刀口滤波位置,设计并加工制作了自适应的刀口滤波系统,解决了通过手工调节刀口滤波位置带来的精度差、参数难量化、重复性差的问题。分析了大气环境下无基底FPA的热机械性能,通过分析无基底FPA的结构,通过电学模型类比无基底FPA在大气环境下的三个热交换机制,得出无基底FPA在大气环境下仍然具有一定的红外成像的能力,其NETD(噪声等效温差)虽然会有一定程度的降低,但有基底FPA则完全无法热成像。对光学读出红外图像进行了优化研究,不同于电学读出每个测量单元下都集成了一个微读出电路,光读出是通过可见光读出光路测量FPA反光板吸收红外辐射的转角变化,这样很难保证FPA上的一个像元正好对应读出光路中CCD(电荷耦合器件)上的一个像元,本文研究了FPA上的一个像元与采集CCD上一个像元之间的关系,通过满足一定的成像判定条件,将CCD上采集的图像进行了一比一图像重构。同时对无基底FPA自身热串扰复原进行了研究,通过有限元模拟热串扰的幅度和尺度,建立了热串扰复原模型。通过一比一重构和无基底FPA热串扰复原模型,第一次还原了光读出图像和电读出图像的不同,能够将光读出图像化归为目前广泛使用的电读出图像进行处理。对红外热像仪进行了的相关开发应用,集成化、小型化光读出红外热像仪的研制开发中,最重要的是进行FPA芯片的真空封装、可见光读出光路的小型化集成、后端图像采集系统的研发和光读出红外成像软件的开发。针对光读出红外成像自身的特点,考虑到光读出红外图像的重构和热串扰复原,并集成分区校正(分均匀校正)、数字图像细节增强、LED光源亮度、挡板机构等外设调节,开发了光读出非制冷红外热像仪分析软件。目前红外无损检测的发展很快,基于锁相的红外无损检测以其不需要很高的采集帧频和很高的探测精度是未来红外无损检测实用化、工程化的首选。本文还进行了锁相红外无损探伤装置的研究和开发,设计了锁相红外装置并成功用于实验,通过理论分析和实验对比,取得了较好的效果。更多还原

【Abstract】 Except for military uses, uncooled infrared imaging (IR) technology is developing rapidly in recent years, and been widely used in industrial, medical, automotive, monitoring, etc. Our group designed and implemented a novel optical readout uncooled infrared imaging system. On the basis of previous studies, this manuscript does some optimization research on optical readout, the thermo-mechanical properties of the substrate-free focal plane arrays (FPA) under atmospheric conditions and the IR image restoration algorithms.First, this manuscript optimizes optical readout method, and finds that while considering the actual size of LED (light emitting diode) light source, it would cause analytical errors if simplify the LED light source to ideal point light source. Therefore, this manuscript establishes an area light source model to explain that the optical detection sensitivity is not reduced significantly with the FPA reflectors size (the ideal point source model affirms that it should be reduced linearly). Using the Fraunhofer diffraction theory the influence of the optical detection sensitivity on area light source is studied. The dependence of the optical detection sensitivity on light source radius and reflector length of the focal plane array (FPA) is found. And optimized design criteria for the size of light source, the length of the reflector, the focal length of lens and the wavelength of light source are proposed. According to theoretical analysis, the experimental verification is carried out.Based on the analysis of the key parameters in optical readout-edge position of the optimum filter, we find the relationship between the light intensity and the best edge position of the filter, and manufacture an adaptive knife-edge filtering system to solve the problem such as poor accuracy, difficult to quantify parameters, lack of reproducibility by manual regulation.Analysis the mechanical properties of the substrate-free FPA in atmospheric environment. According to the analogy of electrical models, we study the three heat exchange mechanism of the substrate-free FPA in atmosphere, and find that the substrate-free FPA still has certain infrared imaging capability, although the NETD (noise equivalent temperature difference) will be reduce a lot, but the substrate FPA is completely unable for IR imaging.Optimizes the optical readout IR images. Different from electrical readout, which has an integrated micro readout circuit under each unit, optical readout measures the reflective panel angle changes of the unit when they absorb infrared radiation. This is difficult to ensure that one FPA pixel is exactly corresponds with one pixel which is captured on CCD (charge coupled device), this manuscript studies the relations between them and establishes a criterion to estimate the one to one image reconstruction. And the thermal crosstalk of the substrate-free FPA is studied by FEM, it’s propose an image restoration algorithm of infrared target. By this means, we first develops the models to make the optical readout IR image and the electrical readout IR image as the same.At present, the NDT (Non Destructive Testing) is developing rapidly, the lock-in NDT does not require high frame rate and high detection accuracy, and will be widely used in engineering.this manuscript designs lock-in infrared devices for experiment uses, and achieves good results.更多还原