Real-time solar imaging with a 19-segment active mirror system: a study of the standard atmospheric turbulence model

Abstract

A 57-actuator segmented active mirror system designed for real-time correction of phase distortions due to atmospheric turbulence is described. Solar images and wavefront tilt data obtained with the active mirror system during a recent observing run are discussed. The standard model for imaging through atmospheric turbulence is described. Based on this model, mathematical expressions for the atmospheric coherence diameter, the tilt-corrected wavefront phase structure function, and the corrected and uncorrected modulation transfer functions are developed. Analytical expressions as well as functional relationships obtained through computer modeling are presented. The data are analyzed to check for agreement with the theoretical predictions from the standard model. The analyses indicate that while the standard model may be adequate to describe atmospheric turbulence in some instances, it is often quite inadequate. The analyses also show that the degree of correction performed by the active mirror system was less than ideal.