Real-time correlation reference update for astronomical adaptive optics

Abstract

The use of laser guide stars in astronomical adaptive optics results in elongated Shack-Hartmann wavefront sensor image patterns. Image correlation techniques can be used to determine local wavefront slope by correlating each sub-aperture image with its expected elongated shape, or reference image. Here, we present a technique which allows the correlation reference images to be updated while the adaptive optics loop is closed. We show that this can be done without affecting the resulting point spread functions. On-sky demonstration is reported. We compare different techniques for obtaining the reference images, and investigate performance over a wide range of adaptive optics system parameters. We find that image correlation techniques perform better than the standard centre-of-gravity algorithm and are highly suited for use with open-loop multiple object adaptive optics systems.

Accepted by MNRAS

References in corpus (2)

• Temporal variability of the telluric sodium layer
• Monte-Carlo simulation of ELT scale multi-object adaptive optics deformable mirror requirements and tolerances

Cited by in corpus (5)

• Peak-locking centroid bias in Shack-Hartmann wavefront sensing
• On-sky demonstration of matched filters for wavefront measurements using ELT-scale elongated laser guide stars
• Wide-field adaptive optics performance in cosmological deep fields for multi-object spectroscopy with the European Extremely Large Telescope
• Wave-front error breakdown in LGS MOAO validated on-sky by CANARY
• Generating Artificial Reference Images for Open Loop Correlation Wavefront Sensors