Estimation of the Quality Parameters of Bessel Light Beams of Higher Orders

Abstract

A method is proposed to assess the quality of Bessel light beams of higher orders (BLB_n, order n> 0) by analyzing digital computer images of two-dimensional transverse intensity distributions. One image is sufficient to assess the quality in a specific cross-section of the BLB_n. Algorithms are described that ensure the correct implementation of this technique, namely, the algorithm for the annular beam axis position estimation based on cluster analysis, the algorithm of the estimation of the initial approximation of the cane parameter when approximating the experimental diametral intensity distributions by the square of the Bessel function based on the analysis of the spectral power density of diametral intensity distribution. The proposed method and algorithms are implemented as an extension for the software package for analyzing the quality of Bessel light beams. Using a software package, the technique was experimentally tested on the example of analyzing the quality of BLB1 formed using KTP (KTiOPO₄) and KGW (KGd(WO₄)₂) crystals from the radiation of a semiconductor laser module (SCLM) and helium-neon laser (HNL). It is shown that the beam formed from the HNL retains the constancy of the radius along different azimuthal directions and conformity of the shape to the ideal BLB1 at a larger distance from the axicon than the SCLM, but at the same time it loses the constancy of the intensity along different azimuthal directions in the first ring more quickly.