Patent attributes
An illumination device includes a light source device adapted to emit a third light beam including a first component in a first polarization state, a polarization separation element to which the third light beam is input, a retardation element, and a diffusely reflecting element having a concavo-convex structure including a plurality of curved surfaces. The first component having passed through the retardation element via the polarization separation element, is then reflected by the diffusely reflecting element, then passed through the retardation element again, and then enters the polarization separation element. Thus, the fourth component in the second polarization state out of the first component is emitted from the illumination device via the polarization separation element.
