The "camera" is not a "raygun" or a thermal imager, regardless of the discussion of the "cold background" at the CCW Reciprocity site (That is just a way to express the measure of passive (spurious) atmospheric emissions.
The millimeter wave (MMW) imager is a receiver that recieves, and maps for display, the images received in the millimeter wave band. There actually is more than one millimeter wave "band". Millimeter wave emissions are effectively transmitted and received in those portions of the electromagnetic spectrum which have the least hydrogen atom attenuation. Practically speaking, that means water molecules.
The most useable (least atmospheric attenuation) portion of the spectrum for MMW activity is around 30 Gigahertz (30GHz). That is slightly above frequencies used for military radar today.
MMW radar emits pulses and reads the returns from a target, just like a normal radar, just at a higher frequency. This MMW camera, however is a nothing more than a MMW receiver (which does not emit pulses, i.e., not a radar) with an imaging display, exactly like an imaging display attached to a normal radar frequency receiver would work ... with a VERY narrow bandwidth of recieved and processed signals and a VERY high sensitivity to the frequencies of interest.
The most effective passive sensor arrays are those that combine multi-frequency (referred to as multi-spectrum) sensors, such as IR and MMW. The sensor arrays are colocated on a platform and collated in axis (boresighted). They simultaneously map the same images and give a LOT of information about the target. This is called sensor fusion, and this my friends, is probably what is being used.
Okay ... (deep breath), my apologies to the forum for going off on a MMW mini-tutorial, but I just HAD to respond to the "ray gun" stuff.
The boy does get spun up.
Sensop