Formation of fields in resonators with a composite mirror consisting of inverting elements

An analysis is made of the characteristics of the formation of fields in a resonator with a composite mirror consisting of inverting elements and in a resonator with a corner-cube reflector. The lowest oscillation modes are found numerically. It is shown that the nature of the fields which are formed and their diffraction losses are governed by phase relationships between the beams reflected from the mirror elements and by the pattern of their interference in the corner-cube reflector. The diffraction losses in a resonator with a composite mirror are usually less than in a subresonator or a resonator with a plane mirror equivalent to the composite one. It is pointed out that dephasing of the beams reflected from the mirror elements, due to a shift of these beams or due to optical inhomogeneities, alters significantly the diffraction losses only if the Fresnel numbers are sufficiently small.