It is well known that a light spot of sub-wavelength will diverge in all directions. In this letter, A method is presented for generating sub-wavelength (0.44\lambda) longitudinally polarized beam, which propagates without divergence over lengths of about 2\lambda in free space. This is achieved by a high numerical aperture (NA) lens axicon that utilizes spherical aberration to duplicate the performance of an axicon and to create an extended focal line.
© 2008 Chinese Optics Letters
K. B. Rajesh and P. M. Anbarasan, "Generation of sub-wavelength and super-resolution longitudinally polarized non-diffraction beam using lens axicon," Chin. Opt. Lett. 6, 785-787 (2008)