ABSTRACT
The behavior of an electromagnetic wave impinging on a sharp discontinuity was studied in Chapters 4 and 10, under the assumption that the surface of discontinuity extends to infinity, at least in one direction. In the part of Chapter 9 where we dealt with open resonators, we pointed out that the mirrors which delimit them do not satisfy an assumption of this kind. However, until now we did not consider the consequences induced by surfaces of discontinuity limited by rims.
