Side lobe suppression of a Bessel beam for high aspect ratio laser processing

Bessel beams can be used for high aspect ratio laser drilling and for eliminating the need to precisely position materials along the propagation direction during laser drilling and cutting. However, Bessel beams have side lobes that can damage the materials subjected to these beams. This paper discusses optical suppression of side lobes. A method is proposed to suppress these side lobes, and the method is based on interference between two Bessel beams with different wave vectors. The effectiveness of this method is confirmed both theoretically and experimentally by realizing a superposed Bessel beam; using a He-Ne laser (lambda = 633 nm) and an annular binary aperture placed in front of a convex lens, this beam has a 1/e(2) radius of 44 mu m. (C) 2014 Elsevier Inc. All rights reserved.