Polarization effect of cylindrical vector beam in high numerical aperture lens axicon systems

摘要

A method is presented for generation of cylindrical vector beam and also to obtain the polarization effect on focal depth in high numerical apertures (NA) lens axicon optical systems. The generalized cylindrical vector beam is just a linear combination of radial and azimuthal polarization. For radially polarized light in the focal plane, there are two electric field components one is the radial component and second is azimuthal component, whose magnitudes will increases with the increase of numerical aperture (NA). By contrast, for azimuthally polarized light in the focal plane, there is only one electrical field component in the azimuthal polarization, it is easy to understand the difference between the two polarization effects. The high NA lens axicon utilizes spherical aberration to duplicate the performance of an axicon and to create an extended focal line. In this paper, we demonstrate how this phenomenon can be harnessed to make a properly selected polarization component to achieve high focal depth in high NA lens axicon systems. The numerical evaluation of system generates some of the interesting focal spot, focal split and focal patterns. The largest focal depth is achieved, by properly changing the polarization rotation angle of the cylindrical vector beam (the ratio of radial and azimuthal polarization is set properly). We will denote a technique of polarization assisted high focal depth in high NA lens axicon systems.