Focusing of cylindrical-vector beams in elliptical mirror based system with high numerical aperture

A vectorial expression is derived in the case of cylindrical-vector beam illumination for focusing investigations of an ideal elliptical mirror based system with high numerical aperture. It is analytically explained that focusing property of elliptical mirror is related to both parameters of mirror function and focusing angle, but the well known focusing property of parabolic mirror and lens only depends on the focusing angle. Simulation results show that under azimuthally polarized illumination the focusing spot is in doughnut shape, but in radially polarized illumination the focusing spot is a tight spot, which transverse full-width-half-maximum values at 0.4λ and the amplitude of longitudinal component of electric field intensity is 23.37 times that of lateral component. This inhomogeneous energy distribution will be potentially useful for optical scanning microscopy and creation of axial light needles.