Abstract

The propagation of reflected waves in random media produces an enhancement of irradiance at the transmitter plane that is centered on the propagation axis. The behavior of this enhancement is described by the mutual coherence or second moment of the backscattered field. Because the transmitted and reflected waves pass through the same random media, the second moment becomes a fourth moment when expressed as a one-way propagation problem. The leading-order behavior of the backscatter enhancement of a Gaussian laser beam that is reflected from various ideal targets (mirror, diffuse surface, aerosol target, retro-reflector) is determined by using path-integral methods to generate a series solutions for the general fourth moment. The scale of the irradiance enhancement and the scale of the field coherence are related to the physical scales of the one-way propagation problem in the various parameter regimes of the phenomena. The many characteristics of backscatter enhancement may provide new methods for remote sensing of winds, the parameters of the turbulence spectrum, and the boundary-layer energy budget (e.g., heat and momentum fluxes). A surprising consequence of the backscatter enhancement is that turbulence increases system performance for certain laser-radar applications.

© 1990 Optical Society of America