Patent ID: 7258445

Claim:
An optical unit comprising: a light source; a polarization splitter; an image forming element for forming an original image; and a projection lens for projecting light emitted from the light source via said polarization splitter and said image forming element, wherein said polarization splitter comprises: a first glass member; a second glass member; and a polarization splitting layer and an adhesive layer arranged between said first and second glass members, wherein the polarization splitter satisfies: α 2 ×E<6000000; and K>0.5, where α is a coefficient of linear expansion of the first and second glass members (10 −7 /K), E is a Young's modulus of the first and second glass members (10 8 N/m 2 ), and K is a photoelastic constant of the first and second glass members (nm/mm·mm 2 /N).