Wavefront Measurement Using an Angular-Selective Transmission Filter

The effectiveness of free-space laser communications is limited due to wavefront deformations caused by atmospheric optical turbulence. To measure these deformations, we propose using a wavefront sensor that utilizes the angular selectivity of an optical transmission filter. This sensor converts phase gradients into an intensity distribution. This distribution is captured twice for each direction (x and y). The contrast of these two measurements (calculated for each pixel of the detector used) is linearly related to the local wavefront gradient. We use algorithms developed for the Shack-Hartmann wavefront sensor to reconstruct the wavefront from the obtained local gradients. Simulations demonstrate the applicability of the sensor in atmospheric turbulence.