Speaker
Description
High contrast imaging from the ground requires extremely sensitive wavefront sensing to correct the effects of the atmosphere. While the information limits of a wavefront sensor are well known, a practical, robust design that saturates these limits remains elusive. Furthermore, previous work often ignores the effects of amplitude aberrations (scintillation) when considering the fundamental sensitivity of a wavefront sensor. In this work we explore the PIAA-ZWFS, a Zernike-like system with phase-induced amplitude apodization. Inspired by optimal experiment design, we develop a mathematical and simulation framework to evaluate the Fisher information of a design in the presence of both amplitude and phase aberrations. The design is then optimized to minimize the resulting covariance matrix for a single frame. We present optimized designs for different bandwidths (operating up to 40%), mode bases, and telescope apertures including the coming generation of ELTs. The wavefront sensor can also be made optimal for read or photon noise dominated targets, or made robust over a wider range of stellar magnitudes. Hence, our approach also effectively traverses the cost-performance tradeoff in instrument design. We demonstrate improved performance in end-to-end closed loop simulations and share preliminary laboratory results with this architecture. Our designs nearly saturate the information bound for high frequency aberrations (representing a gain of ~10% over a diameter optimized Zernike wavefront sensor (ZWFS)) and a significant improvement at low frequencies (nearly double the sensitivity of a ZWFS). Hence, the proposed approach demonstrates a realistic system for second stage adaptive optics of the future, providing better performance for high contrast imaging at small angular separations.
| Talk category | Splinter 1: Large Infrastructure and instrumentation |
|---|---|
| PhD relevance | 1st |
