BESSEL BEAMS IN THE FOCAL REGION

The nondiffractive propagation of the ideal zero-order Bessel beam is explained in terms of both the geometrical imaging and the interference of spherical waves emitted from the ring source. The source shift with respect to the focal plane of the imaging system is simply related to the divergence of the produced beam. The intensity distribution of the ideal Bessel beam in the focal region is examined for an aberration-free lens of finite aperture. Both the resolution gain at the focal plane and the position of the axial intensity maximum are investigated in dependence on the truncation of the input Bessel beam.