Monte-Carlo modelling of multi-object adaptive optics performance on the European Extremely Large Telescope

TL;DR

This paper uses Monte-Carlo simulations to analyze and optimize the design parameters of multi-object adaptive optics for the European Extremely Large Telescope, balancing performance and cost for proposed instruments.

Contribution

It provides detailed simulation-based recommendations for design trade-offs and cost-effective solutions for multi-object adaptive optics systems on the E-ELT.

Findings

Optimal laser guide star wavefront sensor pixel scale is about 0.7 arcseconds.

Using EMCCD technology for natural guide star sensors improves performance.

Adaptive optics correction is feasible across fields up to 7 arcminutes in diameter.

Abstract

The performance of a wide-field adaptive optics system depends on input design parameters. Here we investigate the performance of a multi-object adaptive optics system design for the European Extremely Large Telescope, using an end-to-end Monte-Carlo adaptive optics simulation tool, DASP, with relevance for proposed instruments such as MOSAIC. We consider parameters such as the number of laser guide stars, sodium layer depth, wavefront sensor pixel scale, actuator pitch and natural guide star availability. We provide potential areas where costs savings can be made, and investigate trade-offs between performance and cost, and provide solutions that would enable such an instrument to be built with currently available technology. Our key recommendations include a trade-off for laser guide star wavefront sensor pixel scale of about 0.7 arcseconds per pixel, and a field of view of at least 7 arcseconds, that EMCCD technology should be used for natural guide star wavefront sensors even if reduced frame rate is necessary, and that sky coverage can be improved by a slight reduction in natural guide star sub-aperture count without significantly affecting tomographic performance. We find that adaptive optics correction can be maintained across a wide field of view, up to 7 arcminutes in diameter. We also recommend the use of at least 4 laser guide stars, and include ground-layer and multi-object adaptive optics performance estimates.