Surface plasmon resonance imaging using a high numerical aperture microscope objective.

We designed, constructed, and tested a surface plasmon resonance (SPR) microscope using a high numerical aperture objective from a commercially available inverted optical microscope. Such a configuration, combined with various methods to shorten the surface plasmon propagation length, achieves diffraction-limited spatial resolution in the transverse direction and near-diffraction-limited resolution in the longitudinal direction. A virtue of the objective-type SPR imaging is that we achieve distortion-free angle-resolved SPR imaging, allowing the angle-dependent reflectivity of the sample to be examined on a pixel-by-pixel basis, thus offering high-resolution information about surface properties.