High-resolution surface-plasmon resonance real-time imaging.

We use surface-plasmon resonance in a silver film to obtain high-resolution real-time images of a transparent dielectric sample in contact with it. A new aspect of the work was the use of radially polarized illumination from a LED at 530 nm to obtain speckle-free images with high spatial resolution along all orientations. The sensitivity to refractive index changes in the sample is estimated to be better than 10(-3), and the modulation transfer function out to spatial frequency 1 microm(-1) was measured.