Patent ID: 7990615

Claim:
A diffractive optical system comprising a diffractive optical element, the diffractive optical system comprising, in sequence from a side opposite to an object side: a first lens component having a first positive lens, and a second lens component having a second positive lens and a negative lens, wherein the diffractive optical element comprises a first diffractive optical member having a first diffractive optical surface, and a second diffractive optical member having a second diffractive optical surface, wherein the first diffractive optical member and the second diffractive optical member are arranged so that the first diffractive optical surface and the second diffractive optical surface are opposed to each other, and wherein a refractive index of the first diffractive optical member and a refractive index of the second diffractive optical member at the d line are different from each other, wherein the first diffractive optical surface and the second diffractive optical surface are arranged so as to be in contact with each other, and wherein the following condition is satisfied: −15 <ΔN d /Δ( N F −N C )<−2, where ΔN d is a refractive index difference between the first diffractive optical member and the second diffractive optical member at the d line and Δ(N F −N C ) a difference between primary dispersions (N F −N C ) of the first diffractive optical member and the second diffractive optical member.