Phase-induced amplitude apodization complex mask coronagraph tolerancing and analysis

TL;DR

This paper analyzes the manufacturing tolerances of complex masks used in high-contrast coronagraphs, using simulations to understand how fabrication errors affect performance and guide process choices.

Contribution

It provides a simulated tolerance analysis of PIAACMC complex masks, identifying key fabrication errors impacting contrast performance.

Findings

Microfabrication errors significantly affect contrast performance.

Monte Carlo simulations help determine acceptable fabrication tolerances.

Guidance for manufacturing processes to produce functional masks.

Abstract

Phase-Induced Amplitude Apodization Complex Mask Coronagraphs (PIAACMC) offer high-contrast performance at a small inner-working angle ($\approx$ 1 $\lambda$/D) with high planet throughput ($>$ 70%). The complex mask is a multi-zone, phase-shifting mask comprised of tiled hexagons which vary in depth. Complex masks can be difficult to fabricate as there are many micron-scale hexagonal zones ($>$ 500 on average) with continuous depths ranging over a few microns. Ensuring the broadband PIAACMC design performance carries through to fabricated devices requires that these complex masks are manufactured to within well-defined tolerances. We report on a simulated tolerance analysis of a "toy" PIAACMC design which characterizes the effect of common microfabrication errors on on-axis contrast performance using a simple Monte Carlo method. Moreover, the tolerance analysis provides crucial information for choosing a fabrication process which yields working devices while potentially reducing process complexity. The common fabrication errors investigated are zone depth discretization, zone depth errors, and edge artifacts between zones.