Apertureless near-field scanning optical microscope based on a quartz tuning fork

Abstract

The design of an apertureless near-field scanning optical microscope (ANSOM) is presented. The system operates in tapping mode with a tungsten tip mounted on a quartz tuning fork, which periodically scatters the near field at the sample surface. The tip-tuning fork structure is made short so that it can accommodate a standard high numerical aperture microscope objective. We describe the mounting of the tip on the tuning fork. Topographical and optical images, in the visible (λ=655 nm) and in the infrared (λ=10.6 μm), of subwavelength holes in a chromium film demonstrate that the ANSOM routinely achieves a resolution of a few tens of nanometers.