Characterization of Pseudo-Random-Phase-Plate as a Kolmogorov/non-Kolmogorov turbulence simulator using statistical parameters and the phase structure function

Abstract

A He-Ne laser lasing at 633 nm is used as source in Mach-Zehnder and Michelson's interferometric geometries separately, for characterizing a Pseudo-Random-Phase-Plate (PRPP), which presents atmospheric turbulence like conditions to a light beam passing through it. Two methods are employed for the same. The first method involves a comparison of the retrieved phase profiles of sections of PRPP (used as object in one of the arms of Mach-Zehnder Interferometer) with those of numerically generated Kolmogorov phase screens, using statistical parameters commonly used for characterizing optically rough surfaces. The second method uses the phase profiles obtained in Mach-Zehnder (single passage through the object, PRPP) and Michelson's (double passage through the object, PRPP) interferometric geometries separately for calculating phase structure function, D φ (r). Through both the methods, we try to determine whether the PRPP presents a Kolmogorov or non-Kolmogorov turbulence regime at 633 nm wavelength. A comparison of the two methods shows that the phase structure function analysis provides a better method for such a characterization.

Fried’s coherence length measurement of dynamic Kolmogorov type turbulence using the autocorrelation function

“…Many attempts have been made to characterize PRPPs. These include phase estimations of turbulence impacted laser beams [4,5] and a systematic characterization using angle-ofarrival fluctuations, Fried parameter, Hurst exponent, turbulence frequencies and the scintillation index [1].…”