A center detection algorithm for Shack–Hartmann wavefront sensor

A modified center position detection algorithm of the spot image for the Shack–Hartmann wavefront sensor was experimentally investigated. The modified center of weight algorithm uses some power from the gray level intensity of the spot images instead of the gray level intensity itself. From the experiments, the repeatability and accuracy of the center position detection of the spot images which used the algorithm were improved when compared with those using the conventional center of weight algorithm. Applications of the algorithm to the measurement of the displacement of the spot images of the Shack–Hartmann wavefront sensor and the experimental results of the closed-loop wavefront correction are described in this paper.