Abstract

Photons incident on a total-internal-reflection surface that is also the object plane of a reflected light microscope will tunnel through a submicron gap in the presence of a dielectric sample. Tunneling increases exponentially with sample height for a homogenous refractive index and is quantified by empirical calibration to a known geometry. Video photometry of the gray-scale tunneling image is converted by a three-axis oscilloscope to real-time three-dimensional topography featuring variable perspective. Vertical resolution is detector-limited to less than 1 nm over a field depth of about 0.75; lateral resolution is enhanced to about 0.3 on extended objects. Photon tunneling images of diamond turned surfaces, optical data structures, polished optical surfaces, and lithographic structures are among those presented. Comparison and correlation with other methods for measuring surface topography in this regime are discussed.

© 1990 Optical Society of America