The Design Of Electrically Controlled Space-Variant Polarization Pupil Filter

For the optical system with low numerical aperture and high numerical aperture, reasearch on design of pupil filter and focus with the diffraction limited is very imporant in optical engineering currently. Filtered by the pupil filter, both of low numerical aperture focus based on scalar diffraction principle and high numerical aperture focus based on vectorical diffraction principle can obtain the redistribution of the intensity near the focus. Not only overcoming the limits of diffraction can be realized, but also many other distribution pattern can be obtained. Many optical application fields can benefit from it including super-resolution, optical microscopy, optical storage, nanopartical manipulation and astronomy. At present, focus with space-variant polarization vector beam plays an important role in vectorial optics.Based on space-variant polorization state controlling technology, combined with electro-optic modulating technology, a new kind of muti-zone electronically controlled pupil filter is proposed in this paper. Modulate linear polarization beam(low numerical aperture) and radially space-variant polarization beam(high numerical aperture) by our pupil filter, three-dimensional focus shaping and controlling can be realized:(1)The electrically controlled pupil filter is composed of two polarizers and a two-zone or four-zone electro-optic crystal between them. Under the low numerical aperture lens focus condition, by modulating the difference of phase retardation between the polarization component of each zone, transverse super-resolution, axial focal shift and extended of depth of focus can be controlled in real time.(2)Under the cylindrical vector beam illumination, focal shift controlling and some special optical focus shape including optical needle,optical bubble can be realized by modulating the polarization state with four-zone electro-optic pupil filter and focusing with high numerical aperture lens. The results show that this kind of electro-optic pupil filter not only can realize multiple beam shaping and real-time manipulating, but also can overcome the limitation which the superresolution properties can not be adjusted with traditional pupil filter. The research results have profound significance to the development of optical super-resoluton technology, optical microscopy technology and nanopartical manipulation technology.