Patent ID: 7359018

Claim:
A retardation optical element, comprising: a transmission type C plate type retardation layer; and a transmission type A plate type retardation layer laminated together with the C plate type retardation layer so that a first surface of the A plate type retardation layer contacts a first surface of the C plate type retardation layer; wherein: the C plate retardation layer has a cholesteric structure including liquid crystalline molecules in planar orientation, a helical pitch of the liquid crystalline molecules being configured such that the C plate type retardation layer selectively reflects light having a wavelength in a wave range that is different from a wave range of incident light; the C plate type retardation layer functions as a negative C plate; the A plate type retardation layer has a nematic structure; the A plate type retardation layer functions as an A plate; directors of liquid crystalline molecules on the first surface of the C plate type retardation layer and directors of liquid crystalline molecules on the first surface of the A plate type retardation layer are arranged in substantially the same direction.