Patent ID: 7995276

Claim:
A laminated wavelength plate in which a first wavelength plate of a phase difference Γ 1 with respect to light of a wavelength λ and a second wavelength plate of a phase difference Γ 2 with respect to the light of the wavelength λ are laminated such that their optical axes cross each other, wherein: in a plurality of wavelength bands λ 1 , λ 2 , λ 3 , which are different from each other, a polarization plane of incident linearly polarized light is converted by having the polarization plane rotated counterclockwise by a rotation angle θ as seen from an incident side, and the converted linearly polarized light is emitted, a relationship of the wavelength bands λ 1 , λ 2 , λ 3 satisfies λ 1 <λ 2 <λ 3 , the wavelength λ is a wavelength included in any of the wavelength bands λ 1 , λ 2 , λ 3 , and when an angle between an optical axis of the first wavelength plate and the polarization plane of the incident linearly polarized light is taken to be an optical axis azimuth angle θ 1 counterclockwise as seen from the incident side, and an angle between an optical axis of the second wavelength plate and the polarization plane of the incident linearly polarized light is taken to be an optical axis azimuth angle θ 2 counterclockwise as seen from the incident side, the following formulas (1) to (3) are satisfied: Γ1=180°+360°× n (1); Γ2=180°+360°× n (2); and θ2=θ1+θ/2 (3), in which n is a natural number beginning with 1, the rotation angle θ satisfies 0°<θ≦90° (4), and the optical axis azimuth angle θ 1 and the optical axis azimuth angle θ 2 satisfy 0°<θ1<90° (5); 0°<θ2<90° (6); and θ1<θ2 (7).