Large field-of-view Shack-Hartmann wavefront sensor based on a high-density lens transfer function retrieval

The Shack-Hartmann wavefront sensor (SHWS) is known for its high accuracy and robust wavefront sensing capabilities. However, conventional compact SHWS confronts limitations in measuring field-of-view to meet emerging applications' increasing demands. Here, we propose a high-density lens transfer function retrieval (HDLTR)-based SHWS to expand its field-of-view. In HDLTR-SHWS, an additional lens is introduced into the measurement system, which converges input wavefront with large aperture onto detectable aperture of sensor. A densely sampling set of phase delays is first employed to retrieve the transfer function of the lens and to isolate lens distortion, which is used to accurately demodulate convergent wavefronts and reconstruct incident wavefronts. We also utilize a global spot matching method to reconstruct the converged wavefront with a large dynamic range. Our experimental results demonstrate that the HDLTR-SHWS expands the field-of-view of SHWS by a factor of 24.9 and achieves an accuracy of less than λ/80.