A quasi-rigorous solution for focusing radially polarized vector beams by an arbitrary opening paraboloid mirror

摘要: For focusing of radially polarized vector beams using an arbitrary opening paraboloid mirror, a quasi-rigorous integral representation light field is derived based on rigorous vectorial diffraction theory electromagnetic waves. Under far-field approximation conditions, the integrals reduce to results from Debye-Wolf integral. Numerical calculations show that marked deviation, as represented by evident focal shift, appears for low-aperture mirrors, e.g. maximum semi-angle α below π/9 with length f being 103λ, or π/6 when reduces 102λ. The radial spot sharpens be 0.39λ (FWHM) and purely longitudinally close 115°, while axial continuously about half wavelength approaching π. annular it possible further compress down 0.36λ (FWHM).