Optical V(z) for high-resolution 2 pi surface plasmon microscopy

Surface plasmons are electromagnetic surface waves whose k vectors are grea ter than that of free-space radiation. We excite surface plasmons by using an oil-immersion lens, which forms one arm of an interferometer. We demonst rate the way in which the characteristic output variation with defocus is d etermined by the propagation properties of the surface plasmons, which lead s to diffraction-limited surface plasmon microscopy in the far field. (C) 2 000 Optical Society of America.