A comparative study of wavefront sensor performance marred by DM Woes

Abstract

The majority of current and future imaging systems on ground-based telescopes utilize high sensitivity wavefront sensors like the non-linear Curvature wavefront sensor (nlCWFS) and the pyramid wavefront sensor (PWFS). The high contrast delivered by these sensors has made the detection of extra-solar planets possible. On the other hand, most legacy systems rely on the Shack-Hartmann wavefront sensor (SHWFS) and its ability to maintain sensitivity to an extended beacon. In the Starfire High-contrast ADaptive Optics Wavefront sensor (SHADOW) lab we have built an optics testbed equipped with an atmospheric turbulence simulator (ATS), and a modular adaptive optics system that can close the loop with a SHWFS, or a nlCWFS, or a PWFS. The calibrated ATS allows a known atmospheric disturbance to be introduced to the system; which can be sensed by the WFS allowing the wavefront to be reconstructed and corrected. The WFS performance is measured by the residual wavefront error or Strehl. The controlled experiment allows us to map out the optimal performance regime for each wavefront sensor as a function of available photons and atmospheric parameters. Our goal is to offer a modular AO system design for on-sky testing where the WFS can be selected based on target magnitude and atmospheric conditions, for optical imaging performance.