Objective lens for optical pick-up
Patent 6594222 Issued on July 15, 2003. Estimated Expiration Date: 
December 27, 2020. Estimated Expiration Date is calculated based on simple USPTO term provisions. It does not account for terminal disclaimers, term adjustments, failure to pay maintenance fees, or other factors which might affect the term of a patent.
December 27, 2020. Estimated Expiration Date is calculated based on simple USPTO term provisions. It does not account for terminal disclaimers, term adjustments, failure to pay maintenance fees, or other factors which might affect the term of a patent.Patent ReferencesDiffractive multi-focal objective lens Single objective lens for use with CD or DVD optical disks Objective lens for optical pick-up Objective lens for optical pick-up Optical pickup apparatus Patent #: 6192021 InventorAssigneeApplicationNo. 747969 filed on 12/27/2000US Classes:369/112.26Plural lens sectionsExaminersPrimary: Huber, Paul W.Attorney, Agent or FirmForeign Patent References
International ClassesG11B 007/00112.25 112.26 Foreign Application Priority Data1999-12-28 JPAbstractDisclosed is an objective lens of an optical pick-up that includes a refractive lens and a diffractive lens structure that is formed as a large number of concentric ring areas having minute steps in an optical axis direction at the boundaries therebetween. The lens surface of the objective lens is divided into a high NA exclusive area for a DVD only, and a common area that is surrouned by the high NA exclusive area. The diffractive lens structure in the common area changes the spherical aberration in the undercorrected direction as the wavelength of the incident laser beam increases. The diffractive lens structure formed in the high NA exclusive area has a smaller wavelength dependence of a spherical aberration than that formed in the common area, and is designed such that a spherical aberration at the short wavelength is adequately corrected for the thin cover type optical disc.Other References
Field of SearchHaving particular optical element or particular placement thereof in radiation beam path to or from storage mediumDiffractive In radiation beam path to storage medium Sectioned optical element Plural diffractive sections Lens section Sectioned optical element Plural diffractive sections Lens section Particular lens | |
