On-axis and off-axis propagation of Gaussian beams in gradient index media.

The object-image formula and an expression for the lateral magnification are obtained for a gradient radial index medium used with Gaussian beams. Angular acceptance conditions for on-axis and off-axis incidence are discussed. Meridional and sagittal sections of a Gaussian beam are analyzed, and numerical methods are used to find the evolution of the beam. The eccentricity parameter of the elliptical spot and the astigmatism of the beam are obtained as a function of propagation distance.