Patent ID: 8149510
Filing Date: 2012-04-03
Classification: G02B

Abstract:
1. A diffractive optical element comprising: a lens body with a blazed grating on an aspheric surface thereof; and an optical adjustment layer that covers the diffraction grating, wherein the lens body is made of a first material and the optical adjustment layer is made of a second material that has a higher refractive index than the first material, and wherein the diffraction grating has a number of ring zones that are arranged concentrically around an optical axis, where the height of each said ring zone with respect to the aspheric surface of the lens body is represented by an increasing function of a distance r from the optical axis, and wherein the increasing function is represented by a phase polynomial that uses the distance r as a variable and that has a magnitude of 3/4π to 7/4π when r=0.