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The Shack-Hartmann wavefront sensor is widely used because of high light energy utilization and the simultaneous measurement of the optical wavefront phase distribution and intensity distribution. The accuracy of the centroid computation has a great influence on the detection accuracy of the Shack-Hartmann wavefront sensor. In this paper, a new method is proposed to improve the accuracy of centroid computation. This method include three steps. First of all, we use a new sliding template method to locate the spot automatically and obtain the approximate center of the spot. Next, we take an adaptive threshold method. After the processing of subtracting the threshold , we use the center of gravity(CoG) method to calculate the spot centroid. A series of simulations are conducted to verify the effectiveness and accuracy of this new method. Compared with the widely-used optimum threshold algorithm and the CoG method, the new algorithm not only enhances the accuracy of centroid computation but also has strong stability.
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