红外摄像机系统常被用来在测试距离上表征像飞机和火箭那样的目标的红外特征,这种距离上的大量空气柱会通过吸收和散射来减弱摄像机所接收到的信号的强度。在清洁的空气中,主要的影响是分子共振吸收,在3μm～5μm的中红外波段,二氧化碳和水气的分子共振吸收尤为特出。红外摄像机可以对远在1000km以外的战术目标进行成像,但在许多情况下,这种目标会处在1km的距离内,例如在近距离低空飞越时。因此,为了预计大气对辐射度测量的影响,有必要对短距离的大气透射进行建模。许多在室外进行的生产过程也需要在数十或数百米的远距离上进行辐射度测量。本文把在1km以内测得的辐射度数据与大气的一个理论模型作了比较,并介绍了一种用以校正短距离大气效应的简单方法。实验数据是用一台配有长焦距透镜和辐射度分析软件的锑化铟凝视列阵摄像机在3μm～5μm波段内收集的。为了测量目标的辐射率,摄像机系统已经过定标,但在目标的带内比辐射率已知的情况下,该摄像机也可用来估计目标的温度。本文把这些辐射度数据同一个基于MODTRAN代码的模型作了比较,并对在“典型”观测条件下由大气造成的标准中距离成像系统所接收的目标信号的衰减作了总结。本文对由透镜系统的调制传递函数产生的影响也作了简单的研究,并据此设定了目标可对着的最小像元数,在此情况下目标仍具有可精确测量的辐射率。 Infrared camera systems are often used to characterize infrared characteristics of targets such as aircraft and rockets at test distances, where the large number of air columns attenuate the intensity of the signal received by the camera by absorption and scattering. In clean air, the main effect is the molecular resonance absorption. In the mid-infrared band of 3μm to 5μm, the molecular resonance absorption of carbon dioxide and moisture is particularly prominent. Infrared cameras can image tactical targets as far as 1000 km away, but in many cases the target will be within 1 km of the distance, such as at low altitude over short distances. Therefore, in order to predict the effects of the atmosphere on radiometric measurements, it is necessary to model the atmospheric transmission over short distances. Many outdoor production processes also require radiometric measurements over distances of tens or hundreds of meters. This paper compares radiation data measured within 1 km with a theoretical model of the atmosphere and presents a simple method for correcting short-range atmospheric effects. The experimental data was collected in the band 3μm to 5μm using an antimony indium agglomeration camera with a long focal length lens and radiometric analysis software. In order to measure the emissivity of the target, the camera system has been calibrated, but the camera can also be used to estimate the target’s temperature, given the in-band emissivity of the target. This paper compares these radiometric data to a MODTRAN-based model and summarizes the attenuation of the target signal received by the standard mid-range imaging system caused by the atmosphere under “typical” observation conditions. In this paper, the influence caused by the modulation transfer function of the lens system has also been studied briefly. Based on this, the minimum pixel number confronting the target can be set. In this case, the target still has an accurately measurable emissivity.