Patent ID: 7894321

Claim:
A laminated wave plate, comprising: a first wave plate having a retardation Γ 1 with respect to a wavelength λ; and a second wave plate having a retardation Γ 2 with respect to the wavelength λ, the second wave plate being laminated with the first wave plate so that an optical axis of the first wave plate and an optical axis of the second wave plate are intersected each other, wherein the laminated wave plate has the retardation Γ 2 as a desired retardation in a range of wavelength from λ 1 to λ 2 , where λ 1 <λ<λ 2 and is structured to satisfy following formulae (1) and (2) if m=Γ 1 /Γ 2 , and ΔΓ 2 =(Γ 22 −Γ 21 )/2: 323°<Γ1≦399° (1); and cos 2θ1=1−(1−cos ΔΓ2)/(2(1−cos mΔΓ 2)) (2), where θ 1 is an in-plane azimuth of the first wave plate, Γ 21 is a retardation with respect to the wavelength λ 1 of the second wave plate, and Γ 22 is a retardation with respect to the wavelength λ 2 .