Characteristics of the intracavity method of IR-signal reception in the atmosphere and the improvement of its noise immunity

An experimental comparison is made between the intracavity and heterodyne methods of reception of a weak optical signal. The efficiencies of these methods are compared on a 200-m long atmospheric path at a wavelength of 10.6 microns. The efficiencies (the signal-to-noise ratio) of both receivers are equal but the sensitivity of the intracavity one is greater. It is shown that the signal fading in the case of the intracavity receiver can be compensated during phase modulation given a sufficiently wide reception band.