凝视型红外搜索跟踪系统的作用距离模型

作用距离是红外搜索跟踪(IRST)系统的核心指标之一,需要对它作专门的研究。从凝视型红外焦平面的响应度和探测目标所需的辐射功率出发,修改了凝视型焦平面响应度的公式,对目标成像的特性进行了新的分析,并讨论了系统各部分对作用距离的影响,建立了凝视型IRST系统作用距离的数学模型,为系统设计和性能评估提供了理论依据。     

日盲型紫外探测系统的探测距离模型及实验研究

日盲区的存在,给近地探测240～280 nm范围的紫外辐射提供了良好的背景.本文设计了一套成像型日盲紫外探测实验系统.从辐射能量传递的角度出发,借鉴凝视型红外搜索跟踪系统的分析方法,推导了紫外探测系统的探测距离模型.以氘灯为探测目标,在三种典型天气条件下对实验系统进行了探测距离实验.结果表明,采用探测距离模型的计算值和实验测量值有较好的吻合,为紫外探测系统的设计和性能评估提供了重要的理论和实验基础.     

中波红外多光谱成像技术研究

多光谱成像技术结合成像和光谱测量技术,同时探测目标的光谱和几何特征,在目标识别和抑制背景杂波方面具有技术优势。研制了一套工作于中波红外波段的四通道多光谱成像系统。利用窄带滤光片和面阵探测器技术,构建了基于时序扫描的凝视成像型红外多光谱成像系统。根据红外探测器性能参数,对各个光谱通道的温度灵敏度进行了估算。在系统设计时通过合理地滤光片布局,尽量延长各个光谱通道的信号积分时间,以提高各个光谱通道温度灵敏度。利用研制的中波多光谱成像系统,对室外进行了成像,并对各个通道的成像结果进行了比较分析。     

航空红外探测新材料的发展方向

海湾战争结束一年多了,但多国部队在实战中展示出的大批高技术武器装备,尤其是航空武器装备仍时时给人启示、催人警醒。通过认真分析多国部队的空中绝对优势和夜间空袭能力,使我们清楚地看到了种种高科技的运用,先进的红外探测技术就是其中之一,而先进的红外探测技术又取决于先进的红外探测材料。     

空空导弹目标特性模型与红外告警体制对比分析

通过概要性研究导弹在不同波段的红外辐射特性,分析面阵凝视型和线阵扫描型两种导弹逼近告警技术体制的优缺点,计算不同体制下对同种目标的探测距离指标,对开展红外告警技术研究具有一定的实际意义。     

CCD探测器搜索跟踪系统的作用距离分析

以辐射度量为标准,从目标信号、背景信号差值与探测器噪声比值的角度出发,变换凝视型红外搜索跟踪系统的作用距离模型,建立了CCD搜索跟踪系统点目标的作用距离方程。解决了目标为发光体、反射体,以及CCD为不同灵敏度表述方式的跟踪系统的作用距离计算,实例验证计算值与实测值相吻合,为CCD跟踪系统的设计和性能评估提供了理论依据。     

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1.315靘, 2.7靘, 3.8靘, 10.6靘的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。     

长波红外对常温目标的跟踪成像研究

靶场观测中存在大量不发光和表面温度接近常温的低温目标,根据它们的光谱辐射特性、背景辐射特性和大气透过率与目标距离的关系,分别选择了中波和长波红外探测器对降落伞进行气球放飞试验。试验结果表明,长波红外探测器对常温目标的探测要优于中波红外。选择分辨力320×256 的碲镉汞探测器作探测能力实验,以 SNR≥5 为可探测条件,当目标表面温度大于 260K时,对直径 5m 的降落伞的作用距离可达 50Km。     

金属板热红外偏振的方向特性研究

热红外偏振探测有利于从背景中识别金属目标.通过分析热红外偏振探测方法,根据现有条件研制了一种热红外成像偏振探测仪.利用该系统,研究了金属板热红外偏振度和观测角之间的关系.实验中采用的金属板分别为铝质和钢质,表面都进行了抛光处理.实验结果表明,金属目标板热红外偏振度和其自身的热辐射亮温值没有直接的关系.在观测角大于20°时,随着观测角度的增大,金属目标板热红外偏振度的数值也增大.但在观测角小于20°时测量,金属目标板热红外偏振度和观测角之间的关系并不遵循上述原则.     

红外焦平面阵列盲元检测算法

为提高红外焦平面阵列盲元的定位精度,分析了盲元的产生机理,指出了探测器所处环境温度对探测元的探测能力以及焦平面阵列的盲元数量和位置分布的影响,提出了一种考虑环境温度差异的红外焦平面阵列盲元检测算法,精确定位了不同温度范围内的盲元位置.实验结果表明,该算法可将随环境温度改变而改变的盲元位置信息准确检测出来.     

回射激光的红外主动跟踪闭环研究

根据激光辐照典型红外光学系统产生回射激光的特性分析,红外装置中焦面上调制盘前表 面产生的回射激光特别适合于激光对红外装置的远距离跟踪、瞄准和工作模式识别。用0.53μm激光辐照红外光学系统产生的回射激光信号触发1.06μm主激光控制系统,实现了主激光对红外装置输出信号的有效干扰。它对利用激光进行红外对抗研究具有重要的参考价值。     

用数学形态学方法进行红外图像分层解理

将形态学算子作用于高噪声,低质量的红外图像,对之进行分层解理还原,即将原本由各种信号叠加而成的红外图像重新分解成器件噪声,工作噪声和目标,背景等不同层次的信号。这种图像解理方法,以几何论和集合运算为基础,因而原理直观,计算简单,能为红外目标识别与跟踪提供有益的预处理。     

基于潜艇声探测能力预测的感知行为决策方法

针对作战行为对潜艇作战结果的影响较大,且难以通过传统基于指标体系的方法来寻求战法创新的问题,提出了基于潜艇声探测能力预测的感知行为决策方法,用于目标搜索阶段的优化决策。首先分析了传播环境、平台特性及作战行为对声探测能力的影响;其次建立了声探测能力的形式化表达,并针对影响因素的特点建立了可实时修正的预测模型,实现行为驱动的声探测能力预测;然后建立了总体约束下的感知行为优化框架及具体优化流程;最后以要地搜反潜为例对所提方法进行了实验验证。实验结果表明,该方法可在目标搜索阶段为感知行为决策提供了有效优化。     

纯角度跟踪的球面坐标降维算法

从解决目标跟踪中的非线性问题入手,分析了不同的解决方法,并结合地面红外搜索跟踪（IRST）系统单独使用时的实际特点,提出了球面坐标降维模型,给出了相应的目标纯角度跟踪算法。目标状态方程和量测方程得到了简化。最后进行了目标跟踪的仿真试验,结果表明这种纯角度跟踪算法具有很好的性能。     

A review of factors influencing defect detection in infrared thermography: Applications to coated materials

Infrared thermography is a technique that is used to nondestructively inspect parts for the presence of subsurface defects. The technique normally consists of applying heat to one surface of the part and observing the thermal response, using heat-sensing devices such as infrared cameras, as the part cools. Internal defects such as voids modify the thermal response and produce local hot or cold spots on the specimen surface. For the detection of subsurface defects, the sensitivity of the technique to different parameters such as defect depth, material properties, and heating methods has not been established due in part to the complex nature of the heat/flaw interaction. A finite element model is used here to examine the influence of these parameters on defect dectability. The model shows that the defect detectability decreases with increasing defect depth beneath the surface, and that the technique is most sensitive to the inspection of low thermal diffusivity coatings bonded to high thermal diffusivity substrates. The results also show that the heat pulse duration should be made as short as possible to maximize defect detectability.     

Infrared small target enhancement: grey level mapping based on improved sigmoid transformation and saliency histogram

Infrared (IR) small target enhancement plays a significant role in modern infrared search and track (IRST) systems and is the basic technique of target detection and tracking. In this paper, a coarse-to-fine grey level mapping method using improved sigmoid transformation and saliency histogram is designed to enhance IR small targets under different backgrounds. For the stage of rough enhancement, the intensity histogram is modified via an improved sigmoid function so as to narrow the regular intensity range of background as much as possible. For the part of further enhancement, a linear transformation is accomplished based on a saliency histogram constructed by averaging the cumulative saliency values provided by a saliency map. Compared with other typical methods, the presented method can achieve both better visual performances and quantitative evaluations.     

Analysis of observer performance in unknown-location tasks for tomographic image reconstruction

Our goal is to optimize regularized image reconstruction for emission tomography with respect to lesion detectability in the reconstructed images. We consider model observers whose decision variable is the maximum value of a local test statistic within a search area. Previous approaches have used simulations to evaluate the performance of such observers. We propose an alternative approach, where approximations of tail probabilities for the maximum of correlated Gaussian random fields facilitate analytical evaluation of detection performance. We illustrate how these approximations, which are reasonably accurate at low probability of false alarm operating points, can be used to optimize regularization with respect to lesion detectability.     

一种新的红外目标跟踪方法

一般的Snake模型用于目标跟踪时存在一些问题,如要求初始控制点位置非常接近于真实 轮廓、不能可靠跟踪快速运动目标、对目标的运动规律有许多约束条件等。在继承所提出的Auto-Snake模型跟踪算法优点的基础上,进一步采用最小二乘估计预测器对目标的位置进行预测,放宽对运动规律的约束,可以实现对快速运动(大位移)的目标的自动跟踪。     

Recent advances in observer performance methodology: jackknife free-response ROC (JAFROC)

The jackknife free-response receiver operating characteristic (JAFROC) method allows quantitative analysis of observer data such as that observed when radiologists interpret images, which could contain more than one lesion and a location can be reported for each perceived lesion. The method was recently validated with a perception-based simulation model that incorporated the detectability parameter of the standard binormal ROC model, and in addition allowed simultaneous samples from both noise and signal distributions. The total number of noise samples is an important new parameter that measures reader expertise. The new sampling model incorporates search, which is an integral part of lesion detection that has not been possible to model until now. The model was used to generate simulated FROC ratings data, which was used to assess the statistical validity of JAFROC analysis. We found that JAFROC analysis is a statistically valid approach for analysing FROC data and that JAFROC analysis exhibited significantly greater statistical power than the existing ROC approach.