Patent ID: 7664002

Claim:
A laminated wave plate comprising: a first wave plate with a phase difference α and an azimuth angle θ 1 with respect to monochromatic light with a wavelength λ, and a second wave plate with a phase difference β and azimuth angle θ 2 with respect to monochromatic light with a wavelength λ, said first and second wave plate being laminated together in such a way that directions of optical axes of said plates intersect each other, so that said wave-plate functions as a phase difference Γ with respect to lights of two wavelengths λ1 and λ2 which are different from each other; characterized in that said wavelength λ is λ=λ1 or λ=λ2, a refractive index of normal ray of said first wave plate is N O1 , a refractive index of abnormal ray of said first wave plate is N e1 and a thickness of said first wave plate is d 1 , a refractive index of normal ray of said second wave plate is N o2 , a refractive index of abnormal ray of said first wave plate is N e2 , and a thickness of said first wave plate is d 2 , said phase differences α and β respectively satisfy following formulas (3) and (4): α=2×π/λ×( N e1 —N o1 )× d 1 (3) β=2×π/λ×( N e2 —N o2 )× d 2 (4) said first wave plate satisfies a Mueller matrix A 1 of a following formula (5): ⁢ ( 5 ) A 1 = [ 1 0 0 0 0 1 - ( 1 - cos ⁢ ⁢ α ) ⁢ sin 2 ⁢ 2 ⁢ θ 1 ( 1 - cos ⁢ ⁢ α ) ⁢ sin ⁢ ⁢ 2 ⁢ θ 1 ⁢ cos ⁢ ⁢ 2 ⁢ θ 1 - sin ⁢ ⁢ α ⁢ ⁢ sin ⁢ ⁢ 2 ⁢ θ 1 0 ( 1 - cos ⁢ ⁢ α ) ⁢ sin ⁢ 1 - ( 1 - cos ⁢ ⁢ α ) ⁢ sin 2 ⁢ 2 ⁢ θ 1 sin ⁢ ⁢ α ⁢ ⁢ sin ⁢ ⁢ 2 ⁢ θ 1 2 ⁢ θ 1 ⁢ cos ⁢ ⁢ 2 ⁢ θ 1 0 sin ⁢ ⁢ α ⁢ ⁢ sin ⁢ ⁢ 2 ⁢ θ 1 - sin ⁢ ⁢ α ⁢ ⁢ sin ⁢ ⁢ 2 ⁢ θ 1 cos ⁢ ⁢ α ] said second wave plate satisfies a Mueller matrix A 2 of a following formula (6): A 2 = [ 1 0 0 0 0 1 - ( 1 - cos ⁢ ⁢ β ) ( 1 - cos ⁢ ⁢ β ) ⁢ sin ⁢ ⁢ 2 ⁢ θ 2 ⁢ ⁢ cos ⁢ ⁢ 2 ⁢ θ 2 - sin ⁢ ⁢ β ⁢ ⁢ sin ⁢ ⁢ 2 ⁢ θ 2 sin 2 ⁢ 2 ⁢ θ 2 0 ( 1 - cos ⁢ ⁢ β ) ⁢ sin ⁢ 1 - ( 1 - cos ⁢ ⁢ β ) ⁢ cos 2 ⁢ 2 ⁢ θ 2 sin ⁢ ⁢ β ⁢ ⁢ cos ⁢ ⁢ 2 ⁢ θ 2 2 ⁢ θ 2 ⁢ ⁢ cos ⁢ ⁢ 2 ⁢ θ 2 0 sin ⁢ ⁢ β ⁢ ⁢ cos ⁢ ⁢ 2 ⁢ θ 2 - sin ⁢ ⁢ β ⁢ ⁢ sin ⁢ ⁢ 2 ⁢ θ 2 cos ⁢ ⁢ β ] ( 6 ) an incident light input to said laminated wave plate is expressed by a Stokes vector T of a following formula (7): T = [ t 1 t 2 t 3 t 4 ] ( 7 ) an emitted light output from said laminated wave plate is expressed by a Stokes vector S of the following formula (8): S = [ S 1 S 2 S 3 S 4 ] ( 8 ) a relationship between said Stokes vector T and said Stokes vector S satisfies the following formulas (9) and (11): [ S 1 S 2 S 3 S 4 ] = A 2 · A 1 ⁡ [ t 1 t 2 t 3 t 4 ] ( 9 ) S = A 2 · A 1 ⁡ [ 1 1 0 0 ] ( 11 ) wherein when said phase difference Γ of said laminated wave plate is expressed by a following formula (12): Γ = arc ⁢ ⁢ tan ⁢ ⁢ ⁢ S 3 S 1 2 + S 2 2 ( 12 ) said phase difference Γ in said wavelength λ1 and said wavelength λ2 satisfied a following formula: Γ=(2× N− 1)×(π/2) wherein N is a positive integer.