Wavefront noise reduction in a Shack-Hartmann wavefront sensor using Kalman filter

Accuracy of centroid coordinates is influenced by a noise in the intensity image that is received from a wavefront sensor. The noise on the intensity image introduces uncertainty to the centroid coordinates, and consequently to the reconstructed wavefront. The analytical model of wavefront noise caused by light noise is proposed. The model accounts an ADC resolution and centroid spots parameters that allow estimating the signal-dependent noise for various quantisation levels. A Kalman-type filter was developed for noise reduction that uses the proposed model of wavefront noise. The comparison between the noised and filtered signals for various quantisation levels is provided.