Mechanisms of the plasma spatial filter for high-power lasers

Abstract
We describe mechanisms operating in the plasma spatial filter. Curvature of the critical density surface of the blow‐off plasma causes high and intermediate spatial frequencies on the incoming laser beam to be rejected. In addition, time‐dependent plasma motions result in the masking of high spatial frequency information on a time‐integrated near‐field photograph of the beam. Effects on the spectrum of the reflected laser light are evaluated.