Heterodyne reception of optical signals at 10.6 μ wavelength

A description is given of a method and apparatus suitable for the measurement of the sensitivity threshold of an optical heterodyne receiver. The results are reported of the measurements of parameters of a heterodyne receiver operating at λ = 10.6 μ in conjunction with photodetectors of various kinds. The possibility of determination of the quantum efficiency of a photodetector from the heterodyne sensitivity threshold is considered.