title: Three-dimensional shape-controllable focal spot array created by focusing vortex beams modulated by multi-value pure-phase grating.
abstract: We propose a method for creating a three-dimensional (3D) shape-controllable focal spot array by combination of a two-dimensional (2D) pure-phase modulation grating and an additional axial shifting pure-phase modulation composed of four-quadrant phase distribution unit at the back aperture of a high numerical aperture (NA) objective. It is demonstrated that the one-dimensional (1D) grating designed by optimized algorithm of selected number of equally spaced arbitrary phase value in a single period could produce desired number of equally spaced diffraction spot with identical intensity. It is also shown that the 2D pure-phase grating designed with this method could generate 2D diffraction spot array. The number of the spots in the array along each of two dimensions depends solely on the number of divided area with different phase values of the dimension. We also show that, by combining the axial translation phase modulation at the back aperture, we can create 3D focal spot array at the focal volume of the high NA objective. Furthermore, the shape or intensity distribution of each focal spot in the 3D focal array can be manipulated by introducing spatially shifted multi vortex beams as the incident beam. These kinds of 3D shape-controllable focal spot array could be utilized in the fabrication of artificial metamaterials, in parallel optical micromanipulation and multifocal multiphoton microscopic imaging.
authors.forename: Linwei
authors.initials: L
authors.lastname: Zhu
authors.forename: Meiyu
authors.initials: M
authors.lastname: Sun
authors.forename: Mengjun
authors.initials: M
authors.lastname: Zhu
authors.forename: Jiannong
authors.initials: J
authors.lastname: Chen
authors.forename: Xiumin
authors.initials: X
authors.lastname: Gao
authors.forename: Wangzi
authors.initials: W
authors.lastname: Ma
authors.forename: Dawei
authors.initials: D
authors.lastname: Zhang