Thermal limitations on the sensitivity of laser-illuminated multibeam interferometers

The sensitivity of an interferometer, when a high-power laser is used, is limited by the amount of power which can be dissipated within the interferometer without causing a deterioration in its characteristics. An analysis was made of the optimization of interferometers for maximum signal/noise ratio with a given power dissipation. It is shown that the best results are obtained by recording the light reflected from an interferometer, and not transmitted through it. The detectivity threshold for small displacements associated with thermal effects is roughly 10^–11 nm·W^1/2·Hz^–1/2 for the present-day dielectric mirror manufacturing technology.