# Phase-Retrieval-Based Wavefront Metrology for High Contrast Coronagraphy

## TL;DR

This paper presents a wavefront measurement technique using phase retrieval for high-contrast coronagraphs, demonstrating significant wavefront correction on the HiCAT testbed to enhance imaging performance.

## Contribution

It introduces a parametric phase-diverse phase retrieval method for in-situ wavefront characterization in coronagraphs, achieving high-precision corrections.

## Key findings

- Wavefront RMS reduced from 16 nm to 3.0 nm
- Method improves coronagraphic wavefront quality
- Applicable to complex aperture telescopes

## Abstract

We discuss the use of parametric phase-diverse phase retrieval as an in-situ high-fidelity wavefront measurement method to characterize and optimize the transmitted wavefront of a high-contrast coronagraphic instrument. We apply our method to correct the transmitted wavefront of the HiCAT (High contrast imager for Complex Aperture Telescopes) coronagraphic testbed. This correction requires a series of calibration steps, which we describe. The correction improves the system wavefront from 16 nm RMS to 3.0 nm RMS.