Improving detection accuracy of extreme-few-pixel Shack-Hartmann wavefront sensor based on tilt modulation

Abstract

Conventional high spatial resolution Shack-Hartmann wavefront sensors have difficulty realizing high-precision wavefront detection under extreme-few-pixel conditions. A method of Shack-Hartmann wavefront sensor based on tilt modulation is proposed. The proposed method first increases the amount of sub-spot image information. Then, the corresponding wavefront detection accuracy can be improved by tuning parameters such as modulation amplitude, modulation angle, and modulation number. Finally, the detection accuracy for different parameter settings is fitted statistically. As observed in numerical simulations and experiments, the tilt modulation-based method effectively improves detection accuracy. Moreover, there are obvious advantages over the conventional Shack-Hartmann wavefront sensors in 4 × 4 sub-aperture pixels and a short focal length of the microlens array, which improves detection accuracy by about 84% in the experiments. Realization of the need for high spatial resolution and high detection accuracy of Shack-Hartmann wavefront sensors.