METHOD FOR CHANGING THE FOCUSING LENGTH OF A 0-ORDER BESSEL BEAM Russian patent published in 2020 - IPC G02B27/16 

FIELD: optical instrument making.

SUBSTANCE: invention relates to the field of optical instrument-making and can be used in laser optoelectronic devices, where it is necessary to smoothly change the focusing length of the Bessel beam of 0-th order while keeping its core diameter constant. Essence of the invention consists in using a laser which generates a Gaussian beam and a laser variosystem of two lenses and an axicon, in which, by a nonlinear law, the longitudinal position and focal length of the first lens are changed, second fixed lens with constant focal distance is set at focal distance from beam-tightening after first lens, and axicon – in rear focal plane of second lens. At the output of the laser variosystem, 0-order Bessel beam with a constant core diameter and variable focusing length is formed by coordinated movement and focal distance of the first lens. Law of variation of parameters of the laser variosystem takes into account expressions of laser optics, which describe formation of a Gaussian beam and a Bessel beam of 0-th order by optical elements and systems.

EFFECT: smooth variation of the focusing length of the Bessel beam of 0th order based on the laser variosystem.

1 cl, 4 dwg