CHARACTERIZATION OF LABORATORY-GENERATED TURBULENCE BY OPTICAL-PHASE MEASUREMENTS

The resolution achieved by an optical imaging system in the presence o f the random effects of the atmosphere is severely degraded from the t heoretical diffraction limit. Techniques exist for recovering near dif fraction-limited performance of an imaging system in the presence of a tmospheric turbulence. These image enhancement techniques include spec kle imaging, deconvolution, and adaptive optics. A turbulence chamber has been designed and built for laboratory testing of current and futu re adaptive optics and image enhancement techniques. The turbulence is produced within a chamber consisting of two small fans and a heating element. The effects of the generated turbulence on optical propagatio n are directly measured by sensing the perturbed wavefront phase. The wavefront phases are measured using a shearing interferometer. The sta tistical properties of the turbulence are then characterized by means of estimating the phase structure function from the wavefront phase me asurements. We found that the estimate of the phase structure function depends only on the magnitude of the separation between two points on the optical wavefront and follows the Kolmogorov 5/3 power law.