Diffraction of the optical wave in the schmidt cassegrain telescope

The paper is focused on analysing of the distribution of optical intensity within a laser beam at the focal plane of the receiving optics which is affected mainly by diffraction of the optical wave in the Schmidt-Cassegrain telescope. The paper discusses the differences between diffraction of the optical wave on circular and annular aperture. In order to simplify the model of diffraction the Schmidt-Cassegrain telescope was approximated by annular aperture. This simplification seems to be valid according to experimental measurement which was carried out at the laboratory. The aim of the paper is to determine how the obscuration of the telescope affect the coupling efficiency of the Fully Photonic Receiver. Fully Photonic Receiver is used for direct coupling of the optical wave from free space to the single-mode optical fiber.