The Ideal Photon Detector

Abstract

We now treat the optical and infrared detection process by postulating the ideal photon detector. This is a device that samples the incident radiation and produces a current proportional to the total power incident upon the the detector surface. We first consider the fundamental principles of detection, then the noise associated with the detection process, and, finally, analyze two limiting forms of detection, signal-noise limited and background-noise limited. In the latter case, we shall use the results of Chapter 1 to find the limiting sensitivity in the presence of thermal radiation. The treatment in this section ignores noise from the following amplifier stages as well as noise sources peculiar to real devices; however, the results set the absolute limits of sensitivity for a device that exhibits ideal behavior.