| 摘要 |
PURPOSE: To satisfy the RMS wavefront aberration and the ray aberration for both DVD and CD by using a means which shifts a part of the faces of lenses in the direction of the optical axis of optical elements including an objective lens in a region which is used for both DVD and CD. CONSTITUTION: The optical system of an optical pickup device of DVD and CD is provided with a function which refracts light which passes through a region used for recording or reproducing information both for DVD and CD so that the spherical aberration becomes under on a DVD and over on a CD, and a function which gives optical path differences in which the light is divided into a plurality of ring bands coaxial with the optical path, and adjacent ring bands are so formed dislocated in the optical axis direction from each other to make optical path differences approximately integer times prescribed wavelength λs (λ1<λs<λ2), and the optical path of the light gradually increases in the radial direction from the optical axis to the periphery.
|
