Patent ID: 8279523

Claim:
A polarization conversion element, comprising: a plurality of light transmitting substrates sequentially bonded at a plurality of inclined planes thereof that form an angle of approximately 45° with respect to a light incident face and a light emitting face being approximately parallel to the light incident face; a retardation plate providing a phase difference to incident polarized light; a polarization separation film separating incident light into two types of polarized light; and an air layer, wherein the polarization separation film and the air layer are alternately on the plurality of inclined planes that are sequentially bonded, the light transmitting substrates adjacent each other at the air gap layer have reflection faces, and the air layer has a gap, in a direction orthogonal to the reflection faces, of about 10μm with respect to incident light in a visible light wavelength range from approximately 400nm to approximately 700nm, the air gap layer includes spacers formed on the plurality of inclined planes of the light transmitting substrates that are adjacent to each other, and a height of the spacers in the direction orthogonal to the reflection faces is the same as the gap of the air layer.