Subaperture wavefront measurement using Talbot interferometry

Various methods can be used to measure optical wavefronts, one of the most widely used is Shack Hartmann sensing. In this case, however the use of microlens arrays for wavefront sensing comes along with a limited lateral resolution.Recently, wavefront sensing based on the Talbot interferometry has been considered to be a good alternative to the Shack–Hartmann method. It was confirmed that the replacement of the lenslet array by a diffraction grating eliminates some limitations of the Shack–Hartmann sensor especially regarding the device flexibility.For the measurement of large optical wavefronts, a new method based on subaperture stitching of freeform wavefronts is proposed. It is applied to the data acquired using a scanning modified Talbot sensor. The complete wavefront is divided into a number of subapertures with some overlapping zones. Each subaperture is measured using a 2-dimensional grating and Fourier filtering. By scanning the entire wavefront, it is possible to reconstruct it. A mathematical model for stitching algorithm is developed.Simulation studies are conducted. Furthermore the proposed mathematical model is verified experimentally.