Patent ID: 6865025

Claim:
An aberration compensating optical element comprising: a single lens, comprising: a first optical surface comprising a diffractive structure comprising a plurality of ring-shaped zone steps formed on a plane surface; and a second optical surface opposite to the first optical surface, the second optical surface comprising a concave refractive surface; wherein the single lens satisfies the following relation: P λ1 <P λ0 <P λ2 wherein P λ0 represents a paraxial power (mm −1 ) of the single lens at a wavelength λ 0 of a light flux, which passes through the single lens; P λ1 represents a paraxial power (mm −1 ) of the single lens at a wavelength λ 1 , which is 10 nm shorter than the wavelength λ 0 ; and P λ2 represents a paraxial power (mm −1 ) of the single lens at a wavelength λ 2 , which is 10 nm longer than the wavelength λ 0 .