Focusing of millimeter-wave radiation beyond the Abbe barrier

A hemispherical focusing system for millimeter waves is presented. Focusing of the beam to a spot of similar to0.3lambda was obtained in the frequency range from 100 to 200 GHz. Compared to the scanning near-field optical spectroscopy, the system allows simultaneous imaging of extensive subwavelength objects. As an example, a double slit of size d=1 mm was clearly resolved using a radiation with a wavelength lambda=2 mm. Using future optically dense lenses, a resolution of the order lambda/100 seems to become possible. (C) 2003 American Institute of Physics.