Lyot-based Ultra-Fine Pointing Control System for Phase Mask Coronagraphs

TL;DR

This paper introduces the Lyot-based pointing control system (LPCS), a novel method for precise low order aberration control in phase mask coronagraphs, enhancing starlight rejection and planet detection capabilities.

Contribution

The paper presents a new LPCS concept that uses residual starlight reflected by the Lyot stop to accurately measure and control pointing errors in coronagraphs.

Findings

Pointing errors measured with 2-12 nm accuracy at 1.6 microns.

LPCS improves low order aberration control in phase mask coronagraphs.

Simulation results demonstrate effective error correction.

Abstract

High performance coronagraphic imaging at small inner working angle requires efficient control of low order aberrations. The absence of accurate pointing control at small separation not only degrades coronagraph starlight rejection but also increases the risk of confusing planet's photons with starlight leaking next to the coronagraph focal plane mask center. Addressing this issue is essential for preventing coronagraphic leaks, and we have thus developed a new concept, the Lyot-based pointing control system (LPCS), to control pointing errors and other low order aberrations within a coronagraph. The LPCS uses residual starlight reflected by the Lyot stop at the pupil plane. Our simulation has demonstrated pointing errors measurement accuracy between 2-12 nm for tip-tilt at 1.6 micron with a four quadrant phase mask coronagraph.