Image enhancement of Shack-Hartmann wavefront sensor with non-uniform illumination

The uniformity of illumination can affect the detection ability of the Shack-Hartmann wavefront sensor to a certain extent and degrade the wavefront restoration accuracy. When the intensity distribution of the incident beam is very non-uniform, it is difficult for each sub-spot image to carry out optimal signal-to-noise ratio (SNR) at the same time. The spot image may be over-exposed or too dark, and that brings about the incorrect measurements of the centroid and further influences the reconstruction accuracy of the wavefront. In the paper, we use multi-frame image information fusion to generate an enhanced spot-array image with a high dynamic range, so as to improve the accuracy of the overall centroid calculation. The simulation results show that this method is effective in the above cases.