Coherent Phenomenon in Reflection of Radiation by an Uneven Mirror

First experimental results are presented for a coherent phenomenon in reflection of radiation by a mirror with a concave round surface. It consists of interference fringes which arise owing to the interaction of rays undergoing different numbers of reflections on the mirror. An analytical theory of the phenomenon is given in the frame of a geometrical optics approach in a small angle approximation. The experimentally measured interference fringes for the visual light of a Ne–He laser reflected by the round part of the mirror are qualitative coincidence with the results of accurate computer calculations performed in the frame of a geometrical optics approach.