John R. Potter
MPL 0238, Scripps Inst. of Oceanogr., Univ. California at San Diego, 9500 Gilman Dr., La Jolla, CA 92093-0238
Following a successful pilot experiment for the acoustic daylight concept, it is planned to build a multibeam device to form real-time moving images. In support of this design, it is important to investigate the expected performance as a function of object shape, composition, apparent size and the degree and orientation of anisotropy in the illuminating ambient noise field. With such a large number of variables in the operating environment, a simple scattering model is required for the problem to remain tractable. This paper begins with the Helmholtz--Kirchhoff integral and uses the Fraunhoffer approximation, evaluating the integral by stational phase. This closely parallels the work of Funk and Williams [D. E. Funk and K. L. Williams, J. Acoust. Soc. Am. 91, 2606--2614 (1992)]. The analytic result is then summed numerically over ambient noise sources in a distributed field which result in specular scattering onto the receiver from a numerically specified surface. Some examples of simple analytic results and numerical simulations will be presented. [Work supported by the Office of Naval Research.]