Patent ID: 8451538

Claim:
A diffractive optical element, comprising: first and second optical members which are stacked, and which have a diffraction grating formed at an interface between the first and second optical members, wherein expressions (1)-(3) or (4)-(6) are satisfied: 0.400≦λ b ≦0.460 (1) M≧ 1339242229.625×λ b 6 −3467101052.6675×λ b 5 +3739417158.03949×λ b 4 −2150706261.50666×λ b 3 +695699517.122797×λ b 2 −120005677.292515×λ b +8624042.63627238 (2) M≦− 1332094191.9375×λ b 6 +3449257434.95906×λ b 5 −3720886459.39374×λ b 4 +2140458094.5947×λ b 3 −692516647.829495×λ b 2 +119479540.773725×λ b −8587922.98149309 (3) 0.560≦λ b ≦0.650 (4) M≧ 79855185.5390625×λ b 6 −291350087.799711×λ b 5 +442815879.530274×λ b 4 −358873164.839002×λ b 3 +163567486.506001×λ b 2 −39753252.4920047×λ b +4024975.0978217 (5) M≦− 82526017.6289062×λ b 6 +301239002.375121×λ b 5 −458051447.988191×λ b 4 +371372898.921825×λ b 3 −169325896.092434×λ b 2 +41165269.8970695×λ b −4168933.51144255 (6) where “λ b ” is a blaze wavelength (μm); M={n 1 (λ 2 )−n 2 (λ 2 )}/{n 1 (λ 1 )−n 1 (λ 3 )−n 2 (λ 1 )+n 2 (λ 3 )}; “n 1 (λ)” is a refractive index of the first optical member for incident light having a wavelength λ; “n 2 (λ)” is a refractive index of the second optical member for the incident light having the wavelength λ; “λ 1 ” is 0.486133 μm; “λ 2 ” is 0.587562 μm; and “λ 3 ” is 0.656273 μm.