Improvements in the split-window technique for land surfacetemperature determination

Land surface temperature (LST) retrievals obtained from NOAA Advanced Very High Resolution Radiometer (AVHRR) are of considerable importance for climatic research. However, the accurate evaluation of LST from space has been severely limited because of the difficulty in separating atmospheric from surface effects as the surface cannot be modeled as a black-body radiator. With this goal in mind, a novel extension of the split-window technique is presented in which the atmospheric contribution to the radiance measured by the satellite is investigated by the ratioing of covariance and variance of the brightness temperatures measured in channels 4 and 5 of AVHRR/2. Furthermore, the contribution of emissivity is evaluated from coefficients that depend on the spectral emissivities in both thermal channels. Using a wide range of simulations from an atmospheric radiative transfer model it is shown that the proposed algorithm provides an estimate of LST, to within 0.4 K if the spectral surface emissivity is known, which is better than that given by the currently used split-window algorithms for LST determination. Also the limitations on algorithm accuracy are discussed considering different values of noise equivalent temperature. Finally the authors present the preliminary results obtained using the proposed method from AVHRR data over a semi-arid region-of Northwestern Victoria in Australia provided by CSIRO, and a mountainous region of Northeast of France acquired in the frame of Regio Klimat Projekt     

中波红外火情遥感的大气辐射传输特性

分析2005年在广西武鸣机场进行的人工火情测量试验中获得的由BOMEM MR-154FT高光谱仪测定的火情光谱特征发现:在中波4.34～4.76μm光谱段的辐亮度比火情遥感监测常用通道3.5～4.0μm有更强的响应关系.用模拟计算方法进一步分析了中波红外光谱的大气辐射特性.分别对中波波段主要的吸收气体(水汽、水汽连续、二氧化碳混合、二氧化碳、一氧化二氮、臭氧和气溶胶)影响辐射传输的情况进行模拟计算;选择中国内陆地区18种大气廓线样本和4种大气模型,分别进行辐射传输计算,获得了3～5μm谱段分谱大气透过率和大气程辐射等,并比较了新选择通道(4.42～4.78μm)与传统通道(3.55～3.95μm)在地面和传输到大气层顸后辐亮度的变化情况,为今后应用新探测通道奠定了基础.     

Generalization of the thermal model of infrared radiation sensors

In many theories and applications, generalized models can give a good head start for further research where the implementation of new elements and/or boundary conditions could become quite complex. In this paper the development of a compact thermal model of an infrared sensor will be presented. This thermal model includes not only the thermal resistances and capacitances of the sensor structure itself but the radiative and convective thermal resistances to the ambience and between the sensor plate and the heat source (thermal transfer impedance) which is important when the heat source and the sensor are in close proximity. Limitations and the applicability of the proposed model are also discussed. We also aim to present how the proposed model can be used for other IR sensor structures as well.     

UIRFPA热像仪在泡沫红外性能测试中的应用

泡沫是近年来发现的一种新型宽波段无源光电干扰介质,为评价其红外消光性能,采用SAT-HY6800型320×240非制冷红外焦平面(UIRFPA)热像仪,给出了利用红外热像图计算红外消光系数的方法.通过对泡沫的红外热像图的分析,计算得到样品的红外消光系数为0.431m2.g-1;并采用OPAG33傅里叶变换红外光谱仪进行了对比,获得了与前者相似的结果.该结果表明,采用UIRFPA热像仪用于测定泡沫的红外消光系数是可行的,具有较高的准确度.最后分析了这种测试方法的误差因素,为UIRFPA热像仪应用于泡沫红外性能测试提供了指导.     

Occupant posture analysis with stereo and thermal infrared video: algorithms and experimental evaluation

Dynamic analysis of vehicle occupant posture is a key requirement in designing "smart airbag" systems. Vision-based technology could enable the use of precise information about the occupant's size, posture, and, in particular, position in making airbag-deployment decisions. Novel sensory systems and algorithms need to be developed for capture, analysis, and classification of dynamic video-based information for a new generation of safe airbags. This paper presents a systematic investigation in which stereo and thermal long-wavelength infrared video-based real-time vision systems are developed and systematically evaluated. It also includes the design of several test beds, including instrumented vehicles for systematic experimental studies for the evaluation of independent and comparative evaluation in automobiles. Results of extensive experimental trials suggest basic feasibility of stereo and thermal long-wavelength infrared video-based occupant position and posture-analysis system.     

A reappraisal of the use of infrared thermal image analysis in medicine

Infrared thermal imaging of the skin has been used for several decades to monitor the temperature distribution of human skin. Abnormalities such as malignancies, inflammation, and infection cause localized increases in temperature which show as hot spots or as asymmetrical patterns in an infrared thermogram. Even though it is nonspecific, infrared thermology is a powerful detector of problems that affect a patient's physiology. While the use of infrared imaging is increasing in many industrial and security applications, it has declined in medicine probably because of the continued reliance on first generation cameras. The transfer of military technology for medical use has prompted this reappraisal of infrared thermology in medicine. Digital infrared cameras have much improved spatial and thermal resolutions, and libraries of image processing routines are available to analyze images captured both statically and dynamically. If thermographs are captured under controlled conditions, they may be interpreted readily to diagnose certain conditions and to monitor the reaction of a patient's physiology to thermal and other stresses. Some of the major areas where infrared thermography is being used successfully are neurology, vascular disorders, rheumatic diseases, tissue viability, oncology (especially breast cancer), dermatological disorders, neonatal, ophthalmology, and surgery.     

红外热成像技术在亚平面缺陷检测中的应用

根据红外成像无损检测原理,利用机器视觉技术,通过实验将红外热像仪采集的亚表面红外缺陷图像进行一系列的处理,包括滤波降噪,图像增强,边缘提取等,将缺陷检测出来。文中用matlab和Visual C＋＋2010联合编程的方式对红外缺陷进行识别,通过窗口可视化将图像和图像中的缺陷位置,大小提取出来。通过多次实验,本方法能够检测大多的亚平面缺陷,具有较高的应用价值。     

基于TPS54350的红外热像仪电源设计

红外热像仪是一种利用红外探测器将看不见的红外辐射转换成可见图像的被动成像仪器,其对红外图像实时处理的特点要求配套DSP有很高的处理速度.而且,红外设备热敏性高,易受温度等环境因素的影响,在不同的应用场合需要不同的处理方法.     

Correlation between thermal resistance, channel temperature, infrared thermal maps and failure mechanisms in low power MESFET devices

Channel temperature T_ch of GaAs MESFETs, determined by means of electrical measurements (ΔV_gs), has been compared and correlated with thermal maps obtained by high resolution infrared microscopy. Results show that in low power devices with a small number of gates, the value of T_ch derived from ΔV_gs measurements is close to the maximum values of temperature measured on the hottest junctions on the chip. Local thermal inhomogeneities, in particular those observed in devices characterized by high values of R_th, can explain and confirm results of failure analyses of MESFETs submitted to accelerated life tests in operating conditions where degradation phenomena occur in localized areas of the device.     

TEM01*模式输出高功率CO2激光器红外耦合窗热形变半解析方法

为解决高功率CO2激光器高反膜红外耦合窗吸收谐振腔内激光能量产生热效应问题,通过对红外耦合窗镀膜参数和工作特性分析,建立了红外耦合窗的热模型.对热传导方程及其边界条件利用半解析热分析方法得出TEM01*(TEM01+TEM10)模式的CO2激光器红外耦合窗的温度场和热形变计算式,并且对影响红外耦合窗内温度分布的因素进行分析和讨论,发现热模型更符合实际激光器系统,而且TEM01*(TEM01+TEM10)模式在工业领域的应用很广泛,因此对此模式的研究具有重要的实际意义.     

红外热像仪网络远程升级功能的设计与实现

为了降低红外热像仪安装后的系统维护成本,提出了一种基于TCP/IP网络的红外热像仪远程在线升级功能的实现方案。该方案针对基于ARM平台设计的带网络接口的红外热像仪,具体包括PC机上的客服端程序和ARM平台的更新脚本和服务程序。通过客服端程序把升级软件发送到ARM的服务端,再通过更新脚本重新烧写到NANDFLASH,从而...     

The potential role of thermal infrared multispectral scanners in geological remote sensing

Thermal infrared scanners with multiple channels in the 8-14-µm wavelength region are important for geological remote sensing because this spectral region contains important compositional information about silicate rocks and minerals that cannot be duplicated by remote sensors operating elsewhere in the electromagnetic spectrum. Emittance minima in this spectral region, caused by interatomic oscillations, occur at different wavelengths depending on silicate rock type. It has been demonstrated that an image constructed from a signal that is proportional to a ratio of radiances in two thermal scanner channels can be used to map compositional (chemical and mineral) variations in silicates, while suppressing temperature variations across a scanned scene. Theoretical studies indicate that future infrared scanners with eight to twelve channels in the 8-14-µm region might be used to produce an image that could be simply level-sliced (divided into discrete gray levels) to map silicate rocks according to traditional rock classification charts. This is a field in which sensor technology is still the limiting factor. However, improvements in extrinsic sensor properties, especially an increase in the number of spatially coregistered detector elements in a single dewar, are more important than improvements in intrinsic properties, such as detectivity.     

Research and applications of infrared thermal imaging systems suitable for developing countries

It is a common situation in most developing countries that the utilization ratio of the sources of energy is low, the reliability service of equipment is poor, the cost of installation maintenance is high, the loss due to conflagration is heavy, and so on. Therefore, they are in urgent need of using infrared thermal imaging technique to improve their energy saving, equipment diagnosis as well as fire searching. But the infrared thermal imaging systems in the world market so far are not suitable for their use. This paper summarizes the research on two dimensional real time infrared thermal imaging systems on the basis of electron beam scanning and pyroelectric detection, as well as their applications in industry in China.     

应用特征轮廓四边形的热红外图与可见光图配准

热红外图与可见光图的融合分析在智能安防和故障检测中应用广泛.针对同一场景下两图像在融合过程中难以匹配的问题,提出了一种基于特征轮廓四边形的图像配准方法.首先通过分割算法分别对热红外图和可见光图进行过滤;再进行边缘轮廓点的检测和轮廓的重新绘制;然后通过算法筛选出特征轮廓并进行多边形近似,生成特征轮廓的外接四边形;将此四边...     

Dual-colour thermal imaging with InAs/GaSb superlattices in mid-wavelength infrared spectral range

Based on type-II InAs/GaSb superlattice photodiodes, the first report of a dual-colour infrared camera with excellent NETD values<30 mK for the shortwave channel with a cutoff wavelength of 4.0 /spl mu/m and <17 mK for the longwave channel with 5.0 /spl mu/m cutoff is presented. The bispectral system, which offers a simultaneous and pixel-registered detection of both colours, allows remote imaging of carbon dioxide.     

红外成像在羽流撞击平板热效应试验中的应用

为了研究发动机羽流撞击平板的热效应,通过在风洞内建立羽流流场,利用红外热像仪测量平板模型的表面温度,进而获得不同推力产生的羽流撞击平板的热流率分布.首先回顾了高空羽流污染及其效应研究所开展的工作,接着介绍了试验研究所使用的高超声速低密度风洞、红外热像仪等主要仪器设备的性能参数以及平板模型的外形特征,其次给出了2 N与10 N推力的试验条件、热流处理方法、试验结果及其讨论.最后研究了推力喷管轴线与平板距离变化对羽流撞击平板的热效应影响.结果表明:发动机喷管轴线与平板的距离不同,羽流撞击产生的高热流率区域的位置与大小也不相同,距离越小,高热流区域越靠近平板前缘,产生的热效应也越强.     

Quantum corrections to the conductivity of a two-dimensional system with antidots

The quantum corrections to the conductivity of a two-dimensional electron system with antidots in the limit of a small antidot density are investigated. The corrections to the conductivity and magnetoconductivity due to the presence of antidots in a magnetic field perpendicular to the plane of the system are considered. It is assumed that the mean free path l of electrons on the impurities is far smaller than the antidot radius. Fiz. Tekh. Poluprovodn. 32, 1461–1466 (December 1998)