| 摘要 |
PURPOSE:To improve a response characteristic and a recovery characteristic by constituting a liquid crystal cell of a Fresnel lens formed by placing a lot of lenses in the shape of a concentric circle. CONSTITUTION:A titled lens is constituted of a Fresnel lens shape, by which even if the diameter of the lens is made large, an effective thickness of a liquid crystal layer can be set to about the extent of the sum of a depth of a groove part of a lens 6 by a liquid crystal of a Fresnel structure, and a thickness of spacer 4 used for preventing an electric short circuit between electrodes. For instance, when an AC voltage of 10V is applied to the Fresnel lens shape liquid crystal lens 6 of 2cm diameter prepared by using a CPB liquid crystal being a nematic liquid crystal, a focal distance of the lens 6 can be varied continuously in a time of <=one second extending from 17cm which is the value to an abnormal light to 80cm which is the value to a normal light. |
