Patent ID: 7535508

Claim:
An optical element having optical anisotropy, the optical element separating entering light into light rays having polarization directions perpendicular to each other such that the light rays are separated by a specific width and exit from the optical element, wherein the optical element satisfies the following conditions: 0.1 <|n e −n o | θ max <θ where n o and n e represent refractive indices for ordinary and extraordinary rays at a wavelength of 530 nm, θ represents an angle between the direction of an optic axis of the optical element and a normal to an incident surface of the optical element, and θ max represents an angle between the direction of the optic axis and the normal to the incident surface at which the angle of separation is maximized when the light that enters the incident surface of the optical element at the normal angle is separated into the light rays having the polarization directions perpendicular to each other.