Imaging lens

摘要

An imaging lens is provided, whose lens characteristics can be switched between e.g. normal imaging and close-up imaging without requiring mechanically movable mechanism or attachment/removal of another lens. Switching of lens function is realized by combining a liquid crystal diffraction lens and a refractive lens and applying a voltage to a liquid crystal layer of the liquid crystal lens. The liquid crystal lens is constituted by two liquid crystal lenses that are laminated together so that their polarization directions producing lens functions are perpendicular to each other, which suppresses chromatic aberration and achieves good imaging characteristics by appropriately selecting focal lengths and Abbe numbers.