Focusing of linearly-, and circularly polarized Gaussian background vortex beams by a high numerical aperture system afflicted with third-order astigmatism

Effects of third-order astigmatism on the focused structure of linearly and circularly polarized Laguerre–Gaussian beams have been investigated by using vectorial Debye–Wolf integral. The results have been presented for total intensity distribution and squares of the polarization components at the focal plane of a high numerical aperture system, for two values of the topological charge. Astigmatism results in the stretching of the intensity pattern as well as of the squares of the polarization components. A split is observed in the intensity pattern of a focused beam having double topological charge, and also in the pattern of the longitudinal polarization component of circularly polarized beam even with unit topological charge.