Noise-insensitive centroiding algorithm for a Shack-Hartmann sensor

Abstract

A Shack-Hartmann wavefront sensor is the most popular device for wavefront sensing in the field of adaptive optics. The sensing errors of a Shack-Hartmann sensor are caused by various factors, including the noise of a detector, the magnitude and the profile of the spot irradiance distribution, etc. This paper investigates the noise effect in the two major centroiding algorithms, i.e., the center-of-mass method and the correlation method. For this work, wavefront sensing using a Shack-Hartmann sensor is simulated computationally. In this simulation, the input wavefront and the corresponding spot images are generated. Sequentially, the centroids of spots are found, wavefront is reconstructed. From the results of the simulation, an optimal threshold value is proposed for the center-of-mass algorithm. The proposed algorithm is verified through a wavefront-sensing experiment. In the experiment, a wavefront with defocus is generated and measured.