Scanning Near-Field Optical Microscopy (SNOM*): Basic Principles and Some Recent Developments

The elastic scattering efficiency from subwavelength-size surface holes or protrusions depends sensitively on the dielectric properties of their immediate environment. Scanning near-field optical microscopy exploits this effect to create optical images whose resolution is not restricted by the diffraction limit. Typically, 20 nm laterally and, when operated in a topographic mode, 0.1 nm in height can be resolved. Images were obtained both in transmission and reflection. © 1988 SPIE.