Near-infrared wavefront sensing for the VLT interferometer

TL;DR

This paper presents the preliminary design and study of a four-channel near-infrared Shack-Hartmann wavefront sensor for the VLTI, aiming to enhance adaptive optics for the GRAVITY instrument.

Contribution

It introduces a novel four-channel near-infrared wavefront sensor design tailored for VLTI's next-generation instrumentation, specifically for GRAVITY.

Findings

Design of a four-channel near-infrared Shack-Hartmann wavefront sensor.

Feasibility study for simultaneous wavefront measurement of four telescopes.

Instrumental concept development for GRAVITY's adaptive optics system.

Abstract

The very large telescope (VLT) interferometer (VLTI) in its current operating state is equipped with high-order adaptive optics (MACAO) working in the visible spectrum. A low-order near-infrared wavefront sensor (IRIS) is available to measure non-common path tilt aberrations downstream the high-order deformable mirror. For the next generation of VLTI instrumentation, in particular for the designated GRAVITY instrument, we have examined various designs of a four channel high-order near-infrared wavefront sensor. Particular objectives of our study were the specification of the near-infrared detector in combination with a standard wavefront sensing system. In this paper we present the preliminary design of a Shack-Hartmann wavefront sensor operating in the near-infrared wavelength range, which is capable of measuring the wavefronts of four telescopes simultaneously. We further present results of our design study, which aimed at providing a first instrumental concept for GRAVITY.