Modeling 2-D forward-scan sonar imagery for diffuse reflectors

Sonar images are formed by transmitting acoustic pulses and measuring the reflected sound power from the scene surfaces. The recorded signal by a sonar device encodes information about the shape and material properties of these surfaces. In this paper, we present a detailed derivation of an image model for a new class of high-resolution lens-based 2-D forward-look sonar systems, when the diffuse reflectance of scene/target can be characterized as Lambertian. A simplified single patch model is generalized to account for the finite pulse-width of the transmitted beam and the simultaneous arrival of scattered signals from multiple patches at the same range in a given azimuthal direction. Validating the model using intensity measurements of an isolated cylindrical target, we then demonstrate application for multi-path reflections from bottom surfaces.