Statistics of Passive Millimeter-Wave Imaging

Millimeter-Wave (mmW) imaging has gained prominence due to its ability to penetrate obscurants such as clouds, fog, smoke, and dust. Passive detection of naturally-occurring thermal mmW radiation is at the basis of radiometry for remote temperature sensing and of imaging for covert detection of contraband or for navigation in visually degraded environments. This paper explores the principles of thermal radiation in the mmW range, emphasizing the effect of its inherent randomness on detection. The study highlights the difference between direct passive mmW detection and the detection of millimeter waves upconverted to the optical domain, and compares the ultimate limits in the noise performance between the two approaches.