Investigation of the polarisation of powerful laser radiation in multipass cavities with retroreflectors

The nature and the degree of polarisation of optical radiation from a powerful industrial laser were determined experimentally by a method based on measurement of the absorption of the s and p radiation components with a polarimeter. Special attention was paid to selection of the optimal optical configuration of an unstable cavity for high-power lasers with circulating active media. One of such configurations involves the use of retroreflectors, such as a corner reflector or prism, which was investigated. Theoretical estimates were compared with experimental results.