Atmospheric turbulence profiling with multi-aperture scintillation of a Shack–Hartmann sensor

Abstract

ABSTRACT Adaptive optics (AO) systems that use tomographic estimation of the three-dimensional structure of atmospheric turbulence require the vertical atmospheric turbulence profile, which describes turbulence strength as a function of altitude as prior information. We propose a novel method to reconstruct the profile by applying a multi-aperture scintillation sensor (MASS) method to scintillation data obtained by a Shack–Hartmann wavefront sensor (SH-WFS). Compared with a traditional MASS, which uses atmospheric scintillation within four concentric annular apertures, the new method utilizes scintillation in several hundreds of spatial patterns, which are created by combinations of SH-WFS subapertures. Accuracy of the turbulence profile reconstruction is evaluated with Bayesian inference, and it is confirmed that the turbulence profile with more than 10 layers can be reconstructed because of the large number of constraints. We demonstrate the new method with a SH-WFS attached to the 51-cm telescope at Tohoku University and we confirm that the general characteristics of the atmospheric turbulence profile are reproduced.