Improving wavefront sensing with a Shack-Hartmann device
Abstract
In order to achieve higher resolutions, current earth-observation satellites use larger lightweight primary mirrors that can deform over time, impacting on image quality. We evaluated the possibility of compensating these deformations directly in the satellite by combining a deformable mirror with a Shack-Hartman wavefront sensor (SHWFS). The performance of the SHWFS depends entirely on the accuracy of the shift estimation algorithm employed, which should be computationally cheap to be executed on-board. We analyzed the problem of fast accurate shift estimation in this context and propose a new algorithm, based on a global optical flow method that estimates the shifts in linear time. In our experiments, our method proved to be more accurate and stable, as well as less sensitive to noise than all current state-of-the-art methods, permitting a more precise on-board wavefront estimation.
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