A wavefront sensor based on the fractional Talbot effect

Abstract

We propose a wavefront sensor based on the fractional Talbot effect. Optical wavefronts are measured by sampling the light amplitude distribution with a two-dimensional periodic phase grating. At certain fractions of the self-imaging distance, a reference wavefront generates an array of bright spots – the so-called Fresnel images of the grating. The local shifts in the Fresnel images that take place in the presence of wavefront aberrations can be related to the local wavefront slope. In an analysis of the angular and spatial resolution the variable measurement range and accuracy of this method is discussed. Finally some experimental results will illustrate this approach.