title: Atmosphere-like turbulence generation with surface-etched phase-screens.
abstract: We built and characterized an optical system that emulates the optical characteristics of an 8m-class telescope like the Very Large Telescope. The system contains rotating glass phase-screens to generate realistic atmosphere-like optical turbulence, as needed for testing multiconjugate adaptive optics systems. In this paper we present an investigation of the statistical properties of two phase-screens etched on glass-plate surfaces, obtained from Silios Technologies. Those etched screens are highly transmissive (above 85%) from 0.45 to 2.5 microm. From direct imaging, their Fried parameter r0 values (0.43+/-0.04 microm and 0.81+/-0.03 microm, respectively, at 0.633 microm) agree with the expectation to within 10%. This is also confirmed by a comparison of measured and expected Zernike coefficient variances. Overall, we find that those screens are quite reproducible, allowing sub-millimetre r0 values, which were difficult to achieve in the past. We conclude that the telescope emulator and phase-screens form a powerful atmospheric turbulence generator allowing systematic testing of different kinds of AO instrumentation.
authors.affiliation: Max-Planck-Institut für Astronomie Königstuhl 17, D-69117 Heidelberg, Germany. hippler@mpia.de
authors.forename: Stefan
authors.initials: S
authors.lastname: Hippler
authors.forename: Felix
authors.initials: F
authors.lastname: Hormuth
authors.forename: David J
authors.initials: DJ
authors.lastname: Butler
authors.forename: Wolfgang
authors.initials: W
authors.lastname: Brandner
authors.forename: Thomas
authors.initials: T
authors.lastname: Henning