Keizo KONO,^1,2,* Mitsuru IRIE² and Takumi MINEMOTO¹

¹Division of System Science, The Graduate School of Science and Technology, Kobe University, Rokkodai-cyo, Nada-ku, Kobe, 657 Japan, ²Imaging Systems Laboratory, Mitsubishi Electric Corp., Babazusyo, Nagaokakyo-shi, Kyoto, 617 Japan

(Received November 18, 1996; Accepted March 18, 1997)

A new optical system which can efficiently generate the nearly diffraction-free beams is proposed and its characteristics are investigated by numerical analysis. This optical system consists of a new optical element called a DCC (double-concave-cone) lens and an objective lens with a large numerical aperture, and can generate the Bessel beam and also the Bessel-Gauss beam. The maximum propagation distance of nearly diffraction-free beams generated by the system agrees with its theoretical value for the Bessel beam.

Key words : diffraction-free beam, non diffracting beam, Bessel beam, Bessel-Gauss beam, double-concave-cone lens, super resolution