Spectral methods for wave front sensing and reconstruction

Hartmann-Shack sensing is the preferred method for general wave for sensing and for adaptive optics. Wave fronts exhibiting large aberrations pose theoretical and technical challenges. Spectral techniques are used to measure the wave front slopes, and prove to have an edge over the traditional cetroiding methods. We Fourier transform the whole Hartmann-Shack pattern, and isolate the lobes corresponding to the x and y slope information. Demodulation is performed by shifting each of these lobes down to zero frequency, and transforming back. The phases of these two transforms are the gradient components of the wave front. We show results of extensive tests in simulation and in the lab. These methods are seen to perform more efficiently for adaptive optics applications.