Creating a spatial optical tube of prescribed characteristics

Abstract

Based on the radiation pattern of a spatial uniform magnetic current line source (UMLS) antenna, we propose a method for creating a spatial optical tube with a variable length and arbitrary orientation for a 4π focusing system. A virtual spatial UMLS antenna situated at the foci of two high numerical aperture objectives is used to obtain the required illumination at the entrance pupil plane. Numerical results demonstrate that the length of the created optical tube is approximately equal to that of the UMLS antenna. Its orientation is consistent with that of the line source. Its polarization is pure azimuthal, and the transverse size of the optical tube shell and the dark tunnel is uniform over the entire depth of focus. This optical tube can be customized according to application requirements. The generated optical tube can be used for such applications as arbitrary orientation particle trapping and guiding, micromanipulation, and optical microscopy.