AN ANALYSIS OF THE SPATIAL SPECTRUM OF HERMITE-GAUSS BEAMS WITH EMBEDDED OPTICAL VORTEX
This work deals with a detailed theoretical study of Hermite-Gauss beams with embedded vortical phase passing through a lens. Special attention is given to the location of vortical phase singularities in the focal plane. Sufficient conditions for the intensity null in the focal plane centre are found. The theoretical analysis is confirmed by numerical calculations.