On the ultimate detection limits of thermal radiation detectors

The instrumental limits of detectivity of dilatometric, semiconductor and superconducting bolometers are determined. It is shown that even at temperatures of the order of 4°K the Instrumental limits of dilatometric and superconducting bolometers may be lower than the potential limit, resulting from fluctuations in heat transfer between the heatsensing element and its surrounding medium. The instrumental limit of detectivity of semiconductor bolometers at low temperatures is higher than the potential. The level of noise temperature of amplifiers, allowing attaining the potential detectivity is determined.