Application of metal nanoparticles in confocal laser scanning microscopy: improved resolution by optical field enhancement

We describe experiments in which the field enhancement by metal nanoparticles that accompanies surface plasmon excitation has been exploited in confocal laser scanning microscopy. The objective was to make use of the rapid decay of the enhanced light field with distance from the nanoparticles to increase the longitudinal resolution, by confining the emission of fluorescence light to the immediate vicinity of the contact area between the substrate and the objects under study. We demonstrate that the increased longitudinal resolution is accompanied by a better lateral resolution if the imaged objects have a curved surface.