Mirror with reflectance variable in amplitude and phase. 1. Modelling of a mirror with reflectance variablein amplitude and phase

An operator model of a mirror as a reflector with a reflectance variable over the aperture is developed on the basis of a Fabry—Perot interferometer. The main characteristics of the interferometer (mirror) are studied in the geometric, diffraction, and modal approximations. The differences in the calculation results obtained using the conventional geometric approximation and the diffraction approach proposed in this study are discussed. It is shown that, when the effective Fresnel numbers are comparable to unity, it is necessary to use the diffraction approximation. The possibility of using an interferometer-based mirror as a selector of transverse laser modes is demonstrated.