Patent ID: 7113472

Claim:
An optical element, comprising: an optically active polymer film in which an optical rotation property changes in accordance with an outside voltage to be applied, conductive transparent thin films disposed on both sides of the optically active polymer film for applying a voltage to the optically active polymer film, and a transmittance polarization anisotropic part having a different transmittance with respect to a polarization direction, the transmittance polarization anisotropic part being disposed on a side opposite to the optically active polymer film on one of the conductive transparent thin films, wherein the outside voltage to be applied ranges between a first and second voltage, the first voltage providing the optical clement with the optical rotation property capable of making a polarization direction of a light transmitted through the optical element match with that of an incident light, and the second voltage providing the optical element with the optical rotation property capable of making the polarization direction of the light transmitted through the optical element perpendicular to that of the incident light.