Non-Gaussian Speckle Caused By Rough Single Scale Phase Screens

Non-Gaussian speckle can be achieved through the scattering of monochromatic light with a small area of a random phase screen. The random screen is assumed to have a Gaussian probability phase with rms >2π rad and a lateral autocorrelation Gaussian in shape with scale parameter large compared to the rms phase. Numerical solutions for the average intensity and intensity square are presented and compared with the approximate solutions of Jakeman and McWhirter.1 Experimental results are shown to agree with these approximations for rms phase <10 rad. A computer simulation of the same experiment for phase objects up to rms phases of 50 rad gives quantitative agreement with the theory at extreme ranges of effective number of illuminated scatterers but consistently overestimates the theory for the peak of each curve in the family of phases simulated.