Polarization dOTF: on-sky focal plane wavefront sensing

TL;DR

This paper demonstrates the first on-sky implementation of polarization dOTF, a focal plane wavefront sensing technique using polarization diversity, validated through simultaneous Shack-Hartmann measurements at a 1.0m telescope.

Contribution

It introduces a novel on-sky polarization dOTF method using a polarization filter and camera, and validates it with real telescope data for the first time.

Findings

Successful on-sky polarization dOTF measurement at Sutherland telescope

Correlation with Shack-Hartmann wavefront sensor data

Potential for real-time wavefront sensing improvements

Abstract

The differential Optical Transfer Function (dOTF) is a focal plane wavefront sensing method that uses a diversity in the pupil plane to generate two different focal plane images. The difference of their Fourier transforms recovers the complex amplitude of the pupil down to the spatial scale of the diversity. We produce two simultaneous PSF images with diversity using a polarizing filter at the edge of the telescope pupil, and a polarization camera to simultaneously record the two images. Here we present the first on-sky demonstration of polarization dOTF at the 1.0m South African Astronomical Observatory telescope in Sutherland, and our attempt to validate it with simultaneous Shack-Hartmann wavefront sensor images.