Achromatic polymer-dispersed liquid crystal lens with diffractive–refractive hybrid structure

Abstract The focal length of liquid crystal Fresnel lens is electrically controllable, but the disadvantage is the chromatic aberration is obvious. In this paper, the electrically controlled zoom characteristics of liquid crystal lens and the basic theory of Fresnel lens achromatic are analyzed, and a diffractive–refractive hybrid lens model made of polymer-dispersed liquid-crystal (PDLC) material is proposed. Fresnel liquid crystal lenses and PDLC hybrid lenses are tested with light at R (700.0 nm), G (546.1 nm) and B (435.8 nm) wavelengths, respectively. The simulation results show that the hybrid lens provides a greater range of adjustment of the focus position. After voltage modulation, the measured light with three different wavelengths have the same focal length, which means that the axial chromatic aberration is eliminated. In addition, with the elimination of axial chromatic aberration, the zoom range of the hybrid lens is doubled by further accurately controlling the electrode, which breaks through the limitation that the traditional liquid crystal lens can only work in monochromatic light spectrum.