Characterization of atmospheric turbulence phase statistics using wave-front slope measurements

Abstract

Turbulence has long been recognized as one of the most signi cant factors limiting the performance of optical systems operating in the presence of atmosphere. Atmospheric turbulence over vertical paths has been well characterized, both theoretically and experimentally. Much less is known about turbulence over long, horizontal paths. Perturbations of the wavefront phase can be measured using a Hartmann wavefront sensor (H{WFS). These measurements can be used to characterize atmospheric turbulence directly. Theoretical expressions for the slope structure function of the H{WFS measurements are derived and evaluated using numerical quadrature. By concentrating on the slope structure function, we avoid the phase reconstruction step and use the slope measurements in a more direct fashion. The theoretical slope structure function is compared to estimated slope structure functions computed from H{WFS measurements collected in a series of experiments conducted by researchers at the US Air Force's Phillips Laboratory. These experiments involved H{WFS measurements over high altitude (airborne) horizontal paths 20-200 km in length.

Advanced Methods for Improving the Efficiency of a Shack Hartmann Wavefront Sensor

“…In order to make a dynamic microlens array with greater dynamic range, digital SHWS were developed with the help of Liquid Crystal-Spatial Light Modulators (LC-SLMs) (Zhao et al, 2006). It is also possible to characterize atmospheric turbulence using the SHWS via the structure function measurements, C 2 N profile measurements, wind velocity profile estimation and measurement of deviations from the theoretical model of Kolmogorov turbulence (Sergeyev & Roggemann, 2011;Silbaugh et al, 1996). Also, using the SHWS is advantageous over the curvature sensor when large numbers of sensing elements (subapertures) are to be used (Kellerer & Kellerer, 2011) and hence is the best option in large telescope adaptive optics.…”

Ten Years of Research on Light Propagation through a Turbulent Atmosphere

“…Statistical characterization of the image motion is of paramount importance because of its implications in the design of adaptive optics systems. To characterize temporally and spatially the statistics of the wave-front phase cp, several sensing methods have been used [1]. They use single [2], double [3][4], and multiple Shack-Hartmann [5][6] aperture sensors to measure the wave-front tilt.…”

Correlation function of angle-of-arrival measurements with one-dimensional Shack-Hartmann wavefront sensor

“…Atmosphere turbulence has been recognized as one of the most significant factor limiting the performance of optical system. Over the past fifty years， much effort has been devoted to studying the effects theoretically and experimentally 1,2,3,4,5,6 . The Kolmogorov model has been widely applied to research the effects of wave propagating through atmosphere, and usually agrees with the result of experiments.…”