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本文讨论了在研制山林背景的宽瞬时视场红外探测系统时,关于选择对目标探测概率有影响的系统的工作波长范围问题。展宽瞬时视场是为了缩短帧时间,简化扫描结构和提高捕获目标的概率。结果背景辐射的不规则空间变动成了系统输出时的主要噪声。虽然这种噪声可以用空间滤波器去掉,但预先选用能使背景噪声分散小、信噪比好的波段是更重要的。这种系统的最佳工作波长范围可根据由接收到的目标辐射和山林背景辐射空间变动的标准偏差之比最大的条件来选定。若把目标看作一个几十度～几百度的黑体,来求属于中红外区(2～14微米)的大气吸收少的大气窗信噪比,则对100℃以下目标来说,以3～14微米最合适,250℃以上目标以3～4微米最合适。这个结论为野外实验定性确认。
This article discusses the problem of choosing the operating wavelength range of the system that has an impact on the target detection probability when developing a wide instantaneous field of view infrared detection system in the forest background. Widening the instantaneous field of view is to shorten the frame time, simplify the scanning structure and improve the probability of capturing the target. As a result, the irregular spatial variation of the background radiation becomes the major noise at the output of the system. Although this kind of noise can be removed by the spatial filter, it is more important to pre-select the band that makes the background noise disperse and the signal-noise ratio is good. The optimum operating wavelength range for such a system can be selected based on the condition that maximizes the ratio of standard deviations from the spatial variation of the received target radiation and the forest background radiation. If we regard the target as a black body of several tens of degrees to several hundreds of degrees to find the signal-to-noise ratio of the air window which absorbs less air in the mid-infrared region (2 to 14 microns), the target below 100 ° C, 14 microns most appropriate target above 250 ℃ 3 to 4 microns most appropriate. This conclusion is qualitatively confirmed in field experiments.