Multi-spectral piston sensor for co-phasing giant segmented mirrors and multi-aperture interferometric arrays

TL;DR

This paper introduces a multi-spectral piston sensor design for co-phasing large segmented mirrors in future extremely large telescopes, demonstrating feasible measurement accuracies through simulations, despite atmospheric seeing challenges.

Contribution

The paper provides a detailed optical design and numerical validation of a novel multi-spectral piston sensor for co-phasing giant segmented mirrors in ELTs.

Findings

Achieves piston measurement accuracy close to 20 nm

Tip-tilt measurement accuracy close to 10 nano-radians

Feasible for ELT co-phasing despite atmospheric seeing effects

Abstract

This paper presents the optical design of a multi-spectral piston sensor suitable to co-phasing giant segmented mirrors equipping the Future Extremely Large Telescopes (ELTs). The general theory of the sensor is described in detail and numerical simulations have been carried out, demonstrating that direct piston and tip-tilt measurements are feasible within accuracies respectively close to 20 nm and 10 nano-radians. Those values are compatible with the co-phasing requirements, although the method seems to be perturbed by uncorrected atmospheric seeing