Shack–Hartmann Wavefront Sensing Based on Four-Quadrant Binary Phase Modulation

Abstract

Aiming at the problem that it is difficult for the conventional Shack–Hartmann wavefront sensor to achieve high-precision wavefront reconstruction with low spatial sampling, a kind of Shack–Hartmann wavefront sensing technology based on four-quadrant binary phase modulation is proposed in this paper. By introducing four-quadrant binary phase modulation into each subaperture, the technology is able to use an optimization algorithm to reconstruct wavefronts with high precision. The feasibility and effectiveness of this method are verified at extreme low spatial frequency by a series of numerical simulations, which show that the proposed method can reliably reconstruct wavefronts with high accuracy with rather low spatial sampling. In addition, the experiment demonstrates that with a 2 × 2 microlens array, the four-quadrant binary phase-modulated Shack–Hartmann wavefront sensor is able to achieve approximately 54% reduction in wavefront reconstitution error over the conventional Shack–Hartmann wavefront sensor.

Higher-resolution wavefront sensing based on sub-wavefront information extraction

“…intensity distribution, there is a multiple-solution problem. Referring to the article [13] to solve the problem, in this paper, the sub-wavefront is modulated by a four-quadrant binary phase whose expression is given by Eq. 3.…”

“…This method can sense higher-order aberrations [12]. Zhao et al introduced four-quadrant binary phase modulation into each subaperture and used an optimization algorithm to reconstruct the wavefronts with high accuracy [13]. Zhu et al, based on LIFT, proposed the focal technique to sense more Zernike modes in each subaperture and optimized the relative parameters.…”

Shack–Hartmann wavefront sensor based on Kalman filter

“…The centroid offsets are then utilized to calculate the local wavefront gradient in front of the incident wave, and finally, the distortion wavefront can be reconstructed by wavefront reconstruction algorithms 7 , 10 – 13 The center of gravity (CoG) algorithm is a traditional method to calculate the spot’s centroid position by calculating the transverse and longitudinal centers of light intensity per sub-aperture. It has the advantage of low algorithm complexity, but noise significantly affects the spot centroid accuracy.…”