Patent ID: 9562997
Date: 2017-02-07
CPC Classifications: G02B

Claim:
1. An optical system comprising an eccentric prism and a diffractive optical element; wherein the eccentric prism has a non-rotationally-symmetric aspheric surface for correcting eccentric aberration; the diffractive optical element is of a multilayer type having a first diffraction grating and a second diffraction grating with intimate contact with each other, and a diffractive optical surface formed by the first diffraction grating and the second diffraction grating has a lattice structure that is asymmetric about an optical axis of the optical system; and the following condition (1) is satisfied where ΔNe represents the refractive index difference of the diffractive optical surface in relation to the e-line (546.074 nm), and further, the following condition (3) is satisfied, where: Φs represents the refractive power, in relation to the e-line, of a cross-section of the asymmetric lattice structure along which the paraxial power is the strongest; and Φm represents the refractive power, in relation to the e-line, of the asymmetric lattice structure along which the paraxial power is the weakest