Near-field optics is that branch of optics that considers configurations that depend on the passage of light to, from, through, or near an element with subwavelength features, and the coupling of that light to a second element located a subwavelength distance from the first.
Using near-field optical techniques, researchers currently resolve features in the order of tens of nanometers in size.
The notion of developing a near-field optical device was first conceived by Edward Hutchinson Synge in 1928 but was not realized experimentally until the 1950s when several researchers demonstrated the feasibility of sub-wavelength resolution.
Published images of sub-wavelength resolution appeared when Ash and Nichols examined gratings with line spacing less than one millimeter using microwaves of 3 cm wavelength.
In 1982 Dieter Pohl at IBM in Zurich, Switzerland, first obtained sub-wavelength resolution at visible wavelengths using near-field optical techniques.