The Effect of Spherical Aberration on the Spectral Stokes Singularities of Tightly Focused Partially Coherent Anomalous Hollow Beams

摘要

The spectral Stokes singularities of partially coherent radially polarized anomalous hollow beams focused by a high numerical aperture (NA) objective in the presence of spherical aberration is studied in detail by using the vector Debye formula. It is shown that there exist S_(12), S_(23), and S_(31) spectral Stokes singularities. The variation of the spherical aberration, truncation parameter and half angle of the aperture lens will result in the motion, pair creation and annihilation, and changes in the degree of polarization of S_(12), S_(23), and S_(31) spectral Stokes singularities, and the handedness reversal of s_(12) singularities (C-points). The creation and annihilation occur for a pair of S_(12) singularities with opposite topological charge but same handedness, and for a pair of oppositely charged S_(23) or S_(31) singularities, which is similar to the aberration-free case. The collision of an S_(12) singularity with an L-line (S_3 = 0 contour) leads to a V-point, which is located at the intersection of contours of S_(12) = 0 and S_(23) = 0 (or s_(31) = 0) and is unstable. A small perturbation leads to the handedness reversal and changes in the degree of polarization of the C-point. The results have been illustrated numerically and are compared with the results of previous work.