Performance Modeling of a Wide‐Field Ground‐Layer Adaptive Optics System

Abstract

Using five independent analytic and Monte Carlo simulation codes, we have studied the performance of wide field ground layer adaptive optics (GLAO), which can use a single, relatively low order deformable mirror to correct the wavefront errors from the lowest altitude turbulence. GLAO concentrates more light from a point source in a smaller area on the science detector, but unlike traditional adaptive optics, images do not become diffraction-limited. Rather the GLAO point spread function (PSF) has the same functional form as a seeing-limited PSF, and can be characterized by familiar performance metrics such as Full-Width Half-Max (FWHM). The FWHM of a GLAO PSF is reduced by 0.1 ′′ or more for optical and near-infrared wavelengths over different atmospheric conditions. For the Cerro Pachón atmospheric model this correction is even greater when the image quality is worst, which effectively eliminates "bad-seeing" nights; the best seeing-limited image quality, available only 20% of the time, can be achieved 60 to 80% of the time with GLAO. This concentration of energy in the PSF will reduce required exposure times and improve the efficiency of an observatory up to 30 to 40%. These performance gains are relatively insensitive to a number of trades including the exact field of view of a wide field GLAO system, the conjugate altitude and actuator density of the deformable mirror, and the number and configuration of the guide stars.

Durham extremely large telescope adaptive optics simulation platform

“…The GLAO simulation presented here has been compared with other independent AO simulation codes 18 and has been found to be in agreement within the statistical uncertainties.…”

“…18 This checking has been carried out as part of work for the Gemini telescope consortium. The simulation can also be used for situations where the atmosphere cannot be treated as stratified in layers, but as a 3D entity simply by implementing such a model.…”

Solar Ground-Layer Adaptive Optics

“…The software we used for our S-GLAO performance simulations is PAOLA-an Astronomical Adaptive Optics Modeling Toolbox, written by Laurent Jolissaint (Jolissaint 2010). PAOLA is one of five well-recognized software packages which are dedicated for adaptive optics performance simulations, and these codes were thoroughly tested and compared to one another to ensure a high degree of confidence in the results (Andersen et al 2006). PAOLA is free to download and is used by many research groups for AO performance simulations over the world.…”

Wide field astronomical image compensation with multiple laser-guided adaptive optics

“…Hence a singlebeacon GLAO implementation will not be effective for larger apertures. 4 Extremely large telescopes (ELTs) with diameters greater than 25 m will suffer the same problem even with higheraltitude sodium LGS. These telescopes therefore require a further advance in AO technique to exploit their full scientific potential.…”