Patent ID: 6795248
Filing Date: 2004-09-21
Classification: G02B,G11B

Abstract:
An aberration compensating optical element comprising:a diffractive structure having a plurality of ring-shaped zone steps formed on at least one surface of the aberration compensating optical element; wherein the aberration compensating optical element is adapted for being disposed on an optical path between a light source for emitting a light having a wavelength of not more than 550 nm, and an objective lens made of a material having an Abbe constant of not more than 95.0 at a d-line; and wherein the following inequality is satisfied: P&lgr;1&lgr;0&lgr;2, where P&lgr;0 is a paraxial power (mmâˆ’1) of the aberration compensating optical element at the wavelength &lgr;0 of the light emitted from the light source; P&lgr;1 is a paraxial power (mmâˆ’1) of the aberration compensating optical element at a wavelength &lgr;1 which is 10 nm shorter than the wavelength &lgr;0; and P&lgr;2 is a paraxial power (mmâˆ’1) of the aberration compensating optical element at a wavelength &lgr;2 which is 10 nm longer than the wavelength &lgr;0.