Comparison of schemes for active sub-millimeter wave imaging

Abstract

Various schemes for active imaging require different allocations of source power and can result in different overall signal to noise ratios. At the University of Memphis we have developed an image-plane scanning device used with a single pixel detector to form video rate images of the scene. Imaging with this device requires flood illumination of the scene. Because sub-millimeter wave sources typically produce low power, it is a common belief that flood illumination results in low detected signal power and therefore low signal to noise ratios (SNR) at the detector. In this work we quantify the SNR at the detector for our system and compare it to conventional imaging systems, conjugate point imaging systems, and focal plane array imaging. Unlike the other two systems, imaging with our device requires an additional pixel formation step; therefore, the SNR at the detector is not the per-pixel SNR. We present the limits of the per-pixel SNR and discuss its dependence on various device components.