Abstract
The possibility of controlling the spatial structure of laser radiation, and in particular, of forming a diffraction limited beam is the key factor for the majority of laser applications. This problem can be successfully solved by means of a phase conjugation (PC) effect. In principle, PC mirrors allow us to cope with such problems as compensation for highly-inhomogeneous phase distortions, auto-guidance of laser radiation, and phase-locking of individual amplifying channels and segments of optical components. These capabilities are of particular importance for high-power laser systems with dynamically varying inhomogeneities and involving large-aperture optical elements. Accordingly, this report is a review of the history and recent achievements in the development of phase conjugation mirrors (PCM) based on the thermal nonlinear mechanism.