Wavefront sensing with phase singularities

The term "wavefront sensor" denotes a category of devices that can measure the optical wavefront of an incoming beam. Typically, these devices are categorized into interferometer-based and angle-based types. A well-known example of the latter is the Shack-Hartmann sensor, which features a lenslet array that estimates the incoming wavefront by analyzing the displacement of each focal spot from its on-axis position. The calculated slopes are then extrapolated over the entire pupil, facilitating wavefront calculation. In this work, we incorporate phase singularities into the Shack-Hartmann sensor architecture. These optical modes are recognized for their distinctive characteristics, including high sensitivity to any phase disturbances. Furthermore, this method enables the integration of structured light techniques, enhancing spot localization methods that exhibit improved noise resistance. We demonstrate how the new sensor architecture operates under controllable shot noise, providing an efficient solution that preserves phase retrieval capability even in challenging conditions.