Focused ion beam modification of atomic force microscopy tips for near-field scanning optical microscopy

Abstract

A probe for near-field scanning optical microscopy is demonstrated based on a high index glass sphere attached to the end of a conventional atomic force microscopy tip. The sphere is machined into a pyramid geometry using a focused ion beam(FIB) instrument, coated with aluminum to confine the excitation light, and milled further with the FIB to open an aperture at the end of the tip. Near-field fluorescence images of 50 nm fluorescent latex spheres reveal subdiffraction limit spatial resolution, illustrating the utility of these probes for near-field scanning optical microscopy.