WAVE THEORY OF DIFFRACTION

We consider the possibility of developing a theory of diffraction usin g exact solutions of the wave equation. For 2D-diffraction problems, w e classify the diffracted waves able to play the same role as the diff racted rays and we discuss the continuity conditions to be fulfilled b y a wave solution to a diffraction problem as well as the boundary con ditions on a diffracting obstacle. Then, we investigate when this wave theory of diffraction may be used and how to apply it. Two simple exa mples illustrate the kinds of problems to which the method applies.