Interference Effect in Apertureless Near-Field Fluorescence Imaging

Apertureless scanning near-field optical microscopy has been used to image fluorescent latex spheres with a resolution of a few tens of nanometers and good signal-to-noise ratio. The near-field fluorescence images reveal optical interference with several highly contrasted fringes located around the spheres. The origin of the interference is discussed in detail, and models are used to explain their formation. Spatial coherence is also discussed.