Hall J A
Appl Opt. 1971 Apr 1;10(4):838-44. doi: 10.1364/AO.10.000838.
Infrared sensitive television-camera tubes have responsivities orders of magnitude higher than scanner cells, yet the latter give better images of terrestrial scenes by their own thermal radiation. It is shown that although the camera tube electron beam reading mechanism saturates to limit maximum signal-to-noise ratio (SNR) to about 100, the large ir photon flux permits SNR up to 10(5) for typical nonsaturating cells that respond from the visible to 12 microm, despite their lower responsivity. Since ir images have very low contrast, ir sensitive camera tubes would be preferred only for wavelengths shorter than about 2.5 microm where photon flux is small and high responsivity is required.
红外敏感电视摄像管的响应度比扫描单元高几个数量级，然而扫描单元通过自身的热辐射能给出更好的地面场景图像。研究表明，尽管摄像管电子束读取机制会饱和，将最大信噪比（SNR）限制在约100，但对于从可见光到12微米响应的典型非饱和单元，大量的红外光子通量能使信噪比高达10⁵，尽管它们的响应度较低。由于红外图像的对比度非常低，只有在波长小于约2.5微米时，光子通量小且需要高响应度，才会优先选择红外敏感摄像管。
