GPI 2.0 : Optimizing reconstructor performance in simulations and preliminary contrast estimates

TL;DR

This paper explores optimizing the pyramid wavefront sensor in the Gemini Planet Imager using Fourier Optics simulations to enhance phase reconstruction and adaptive modulation, improving robustness and accuracy under varying atmospheric conditions.

Contribution

It introduces a dynamic modulation approach for the pyramid wavefront sensor and analyzes its performance through high-resolution simulations, addressing non-linear response and stability issues.

Findings

Optimized sensor performance with adaptive modulation parameters.

Improved phase reconstruction accuracy under different turbulence conditions.

Enhanced correction of non-common-path errors.

Abstract

During its move from the mountaintop of Cerro Pachon in Chile to the peak of Mauna Kea in Hawaii, the Gemini Planet Imager will make a pit stop to receive various upgrades, including a pyramid wavefront sensor. As a highly non-linear sensor, a standard approach to linearize the response of the pyramid is induce a rapid circular modulation of the beam around the pyramid tip, trading off sensitivity for robustness during high turbulence. Using high temporal resolution Fourier Optics based simulations, we investigate phase reconstruction approaches that attempt to optimize the performance of the sensor with a dynamically adjustable modulation parameter. We have studied the linearity and gain stability of the sensor under different modulation and seeing conditions, and the ability of the sensor to correct non-common-path errors. We will also show performance estimates which includes a comparative analysis of the atmospheric columns above the two mountains, as well as the Error Transfer Functions of the two systems.