Abstract

Knowledge of a material's surface scattering properties is of interest in many fields, e.g., in relating laser radar signatures to the surface properties and underlying shape of a scattering object. The range-resolved cross section U(z) is a signature that carries a great deal of information about the object. It depends on the surface scatter through the monostatic reflectance distribution function f(θ), where θ is the local angle of incidence. We recently demonstrated a technique for measuring U(z) to submillimeter resolutions by flood illuminating the object with a wavelength-scanning Ti:sapphire laser beam and analyzing the fluctuating speckle intensity. In this paper, we begin with an object of known shape, such as a sphere, and calculate the relationship between U(z) and f(θ) analytically. We use axially symmetric objects, illuminated along the axis of symmetry, so that each value of range z maps into a single value of θ. This allows measurements of U(z) to be converted into measurements of f(θ). The signal-to-noise ratio at large θ can be improved by using elongated objects, such as ellipsoids. We compare these results with conventional measurements of f(θ) and find good agreement.

© 1992 Optical Society of America