Layer-oriented adaptive optics for solar telescopes

TL;DR

This paper proposes a layer-oriented adaptive optics approach for solar telescopes, which enhances field-of-view correction by averaging wavefront distortions over wide fields, simplifying system complexity for larger fields.

Contribution

It introduces a layer-oriented method for solar MCAO systems using wide-field Shack-Hartmann sensors, improving scalability and efficiency over star-oriented approaches.

Findings

Layer-oriented approach reduces complexity with larger fields.

Optical tomographic reconstruction is achieved by averaging signals.

System correction loops focus on local turbulence, enabling larger sub-apertures.

Abstract

First multi-conjugate adaptive-optical (MCAO) systems are currently being installed on solar telescopes. The aim of these systems is to increase the corrected field-of-view with respect to conventional adaptive optics. However, this first generation is based on a star-oriented approach, and it is then difficult to increase the size of the field-of-view beyond 60"-80" in diameter. We propose to implement the layer-oriented approach in solar MCAO by use of wide-field Shack-Hartmann wavefront sensors conjugated to the strongest turbulent layers. The wavefront distortions are averaged over a wide-field: the signal from distant turbulence is attenuated and the tomographic reconstruction is thus done optically. The system consists of independent correction loops, that only need to account for local turbulence: the sub-apertures can be enlarged and the correction frequency reduced. Most importantly, a star-oriented MCAO system becomes more complex with increasing field size, while the layer-oriented approach benefits from larger fields - and will therefore be an attractive solution for the future generation of solar MCAO systems.