Shot-to-shot measurement of laser beam quality (M2 parameter) using a distorted diffraction grating

In this paper we present a compact device, which consists of a lens together with 1 or 2 distorted diffraction gratings and a single array detector. This novel arrangement is capable of simultaneously imaging a number of different object planes, and so can provide an instantaneous measure of beam quality. Beam quality can hence be monitored on a continuous or pulse-to-pulse basis.