VECTOR FORMALISM FOR CIRCULARLY SYMMETRICAL LASER-BEAMS

We present a finite dimensional vector formalism that describes the propagation of circularly symmetric beams in a simple and effective way. A propagation matrix operator is explicitly given that determines the amplitude as a function of the radius at any plane. Power transported to a circular or annular target is discussed in some detail. In particular, the problem of choosing a beam shape at the aperture that maximizes the power transported to a target has a simple solution in the new formalism.