Wavefront sensor based on the modified Talbot Effect

Wavefront measurements are important in many fields of applied optics: wavefront control of laser beams, optical diagnostics of the surface, human-eye aberration measurements, etc. The sensor, based on the Talbot effect, can be a good alternative to the Shack–Hartmann sensor. The principle of its work is the self-reconstruction of the image of a linear diffraction grating at the certain distances behind the grating without any optical system, due to interference of diffracted waves. We present a modified method of shearing grating interferometry which allows for the measuring of freeform wavefronts with high accuracy. The experimental results are obtained using a binary amplitude grating and a spatial filter for the zero order. The filtering of the zero diffraction order results in an improved contrast and measurement performance. By means of robust and fast software, we are able to precisely reconstruct the wavefront. A comparison of this method with the other interferometric measurements and a Shack Hartmann sensor is presented.