a Feynman Diagram Approach to Multiple Plane Wave Scattering in Acousto-Optic Interactions.

Because of the mathematical complexities involved, past investigations of acousto-optic interaction tend to obscure the true physical background by making simplifying assumptions concerning the shape of light-and sound fields and the strength of the interaction. In 1979 Korpel developed a true two-dimensional plane wave theory of strong acousto -optic interaction in which such simplifying assumptions are not used. The theory uses a plane wave representation of the fields together with an implicit multiple scattering formalism model for the interaction. It is the purpose of this thesis to work out the implications of the theory. More specifically, the thesis first develops an explicit scattering formalism and introduces the concept of Feynman diagrams which is essentially a method of ordering scattering paths from initial to final states, so as to obtain physically reasonable approximations. The explicit formalism is first applied to obtain the solutions for the well-known Raman-Nath and Bragg diffractions. Next the near-Bragg region and the second order Bragg regime are analyzed. The theoretical results are checked against existing solutions and compared with experimental results. The general problem of arbitrary sound and light field interaction still remains to be solved, but the necessary tools have been developed and tested in this thesis.