Reduction of the focal spot size by using polarization effects

Summary form only. A reduction of the focal area in an optical system with high numerical aperture call be reached if one takes advantage of the polarization distribution of the focused beam. Numerical calculations were performed for a linearly and a radially polarized field distribution considering different intensity distributions. Especially. When an annular aperture is used, the focal area of a radially polarized input beam can be reduced by about a factor of two compared to a linearly polarized beam. The well known phenomenon of increased sidelobes can also be suppressed when rising a radially polarized beam.