Forming of Bessel beams from annular fields on large distances

Bessel light beam formation from annular fields is important for many applications related to laser remote sensing and also for the free-space laser communication. Annular beams have a few advantages, such as optimal combination with optical projectors based on mirror telescopes, self-healing property after passing around obstacles including stability in the atmospheric turbulence in some cases, and also large focal range. In the paper a process of annular beam transformation into a Bessel-type field by the free-space propagation diffraction is investigated. The transverse Bessel beam profile at large propagation distances is calculated. It is shown that the profile contains small number of rings, the on-axis maximum and the first ring contain more than 90% of light power.