Investigation of an unstable resonator with a perforated mirror

Theoretical and experimental investigations are reported of an unstable resonator with a perforated mirror used to couple out information on the phase structure of a radiation wavefront over the whole of its cross section inside the resonator. Estimates are obtained of the precision of determination of the wavefront which, for a given experimental error, makes it possible to determine the permissible size of perforations in the mirror. A numerical investigation is reported of the structure of the field inside a resonator with a perforated mirror when the active medium is subject to low-order aberrations. A report is given of an experimental study which confirms that, in principle, it is possible to use perforated mirrors in unstable resonators for obtaining information on the field structure necessary for the operation of systems with intracavity adaptation.