OSA Student Chapter Talk

Dr. Russell Butts

MZA Associates Corporation

Albuquerque

Department of Electrical and Computer Engineering

University of New Mexico, Albuquerque

Most wave optics codes used to simulate propagation of laser beams through the atmosphere and to predict the effects of atmospheric turbulence employ the split step Fourier method to solve the paraxial wave equation. In the split step method, the continuous atmosphere is replaced, in effect, by a discrete set of thin screens with vacuum between the screens. The screens represent the optical path differences (OPDs) introduced by a slab of the turbulent atmosphere. The split step approach requires methods to generate pseudo random two dimensional arrays with statistics that replicate the statistics of these OPDs. The most widely used method to generate these arrays severely under represents the low spatial frequencies. In this talk, methods for generating the screens based on conditional probability density functions will be described. These new methods produce screens with statistics that match the target statistics to a high degree of accuracy. The new methods can be used to "extrude" phase screens so that new sections of the screens can be added as needed during a simulation. The conditional density function approach is also useful for other applications that require pseudo random arrays, and one example will be briefly discussed.

Friday, January 25th, at 12:00 noon

CHTM, Room 101

A light lunch will be served at the talk.