Patent attributes
A laminated wave plate that corresponds to a plurality of wavelengths including at least two wavelengths of λA and λB, and includes a first wave plate disposed on an incident side and a second wave plate disposed on an emitting side, the first wave plate and the second wave plate being laminated in such a manner that their optical axes are intersected each other, includes the following equations from (1) to (5):ΓA1=360°+360°×2NA (1);ΓA2=180°+360°×NA (2);ΓB1=360°×2NB (3);ΓB2=360°×NB (4); andNB=(ΔnB/ΔnA)×(λA/λB)×(0.5+NA) (5),in whichΓA1 is a phase difference of the wavelength λA at the first wave plate,ΓA2 is a phase difference of the wavelength λA at the second wave plate,ΓB1 is a phase difference of the wavelength λB at the first wave plate,ΓB2 is a phase difference of the wavelength λB at the second wave plate,θ1 is an in-plane azimuth of the first wave plate,θ2 is an in-plane azimuth of the second wave plate,ΔnA is a birefringent difference that is a difference (neA−noA) between a normal ray refractive index noA and an abnormal ray refractive index neA of the wavelength λA, andΔnB is a birefringent difference that is a difference (neB−noB) between a normal ray refractive index noB and an abnormal ray refractive index neB of the wavelength λB,under conditions of θ1=−21°, and θ2=45°.
