Shanghai, China Shanghai Jiao Tong University Shanghai, China (People's Republic)
Alvarez lens, whose focal length can be continuously tuned by changing the relative lateral positions of its sub-elements, holds promise in realizing vari- or multi-focal augmented reality (AR) displays to eliminate vergence-accommodation conflict and 3D visual fatigue. In this paper, we propose and realize a compact Alvarez lens based on planar Pancharatnam-Berry optical elements. We also demonstrate an augmented reality display system using the proposed Alvarez lens, which allows virtual objects to appear at different focal depths.