Optical heterodyne detection

Optical heterodyne detection presents some difficult problems, but for certain applications it offers considerable advantage over the more conventional detection methods. Some of these advantages and problems, and how they are affected by the transmission medium involved, are discussed in this article. Experimental evidence has shown that although heterodyne reception is not desirable at the end of long atmospheric transmission paths, it is entirely feasible for long paths that are enclosed to isolate them from atmospheric disturbances.