DEFOCUSING OF A CONVERGING ELECTROMAGNETIC-WAVE BY A PLANE DIELECTRICINTERFACE

We study how a converging spherical wave gets distorted by a plane die lectric interface. The fields in the second medium are obtained by eva luating the m-theory diffraction integral on the interface. The loss o f intensity and the form of the intensity distribution are investigate d. Examples are presented for various refractive-index contrasts and d epths of focus. In general the intensity gets spread out over a volume that is large compared with the case without refractive-index contras t. It was found that moving the focusing lens a distance d toward the interface does not result in an equal shift of the intensity profile. This latter point has important practical implications. (C) 1996 Optic al Society of America