Patent ID: 8023050

Claim:
An optical device comprising: a vertically aligned liquid crystal cell that holds a liquid crystal layer; a compensating element made of a negative uniaxial refractive material having an optical axis tilted with respect to a system optical axis, and having a fixed positional relation with the liquid crystal cell, an azimuth of the optical axis of the compensating element is the same as an alignment direction of the liquid crystal layer, and the optical axis of the compensating element is inclined with respect to a direction in which liquid crystal of the liquid crystal layer is aligned; an adjustment element having a planar shape and a phase difference in a plane perpendicular to the system optical axis, the adjustment element being disposed in parallel to the liquid crystal layer; and a rotary adjustment mechanism that rotates the adjustment element in the plane perpendicular to the system optical axis to adjust the phase difference influencing light transmitted through the adjustment element, a phase shift of an anisotropic medium as a combination of a refractive index of the liquid crystal layer with no voltage applied thereto and a refractive index of the compensating element in the plane perpendicular to the system optical axis being compensated by the adjustment element.