Holographic Zoom System With Large Focal Depth Based on Adjustable Lens

In this paper, we propose a holographic zoom system based on two adjustable lenses. Different from the traditional holographic system, a digital conical lens and a liquid lens are used as the zoomable lenses. The liquid lens with large effective image aperture is designed and produced by a 3D printer. By mechanically controlling the curvature of the liquid-liquid surface, the focal length of the liquid lens can be changed easily. Compared with the other lenses, the conical lens has a larger focal depth. By encoding the phase information of the conical lens on the liquid crystal on silicon, the focal length and focal depth of the conical lens can be adjusted easily. The liquid lens and conical lens cooperate with each other so as to realize the high quality of holographic zoom projection. With such a system, the size and depth of the reconstructed image can be changed easily according to the requirement. Experimental results verify the feasibility of the proposed system.