Shack-Hartmann wavefront sensor based on a two-dimensional mixed aperture diffractive lens array.

The Shack-Hartmann wavefront sensor (SH-WS) is primarily used to detect the beam wavefront shape, which can be used to detect various perturbations in the atmospheric transmission of high-energy lasers. In this paper, we propose the use of spatial frequency to characterize the shape of the wavefront aberration based on the three-dimensional structure of the Zernike aberration. Based on the characteristics of the frequency distribution of the wavefront, we demonstrate a two-dimensional mixed-aperture diffractive lens wavefront sensor (MADL-WS). Mixed-aperture Fresnel lenses are used instead of the microlens array in SH-WS, and then the aberration information is obtained by the sub-area correlation algorithm. The method synthesizes the requirements of dynamic range and spatial resolution and considers the effect of the signal-to-noise ratio to improve wavefront detection accuracy. The numerical simulations and experimental results show that this method reduces the wavefront mean-square error of Zernike aberration detection. It can more accurately detect the thermal blooming effect generated during high-energy laser transmission.