Patent ID: 6088322
Filing Date: 2000-07-11
Classification: G11B

Abstract:
An optical disk reader or optical read/write system capable of operating in either a compact disk (CD) or digital versatile disk (DVD) format, comprising:disk support and drive means capable of supporting and driving either a compact disk having a disk substrate of thickness Y or a digital versatile disk having a disk substrate of thickness X,a first laser diode operating with an output beam having a first wavelength,a second laser diode operating with an output beam having a second wavelength different from said first wavelength,optical means for either directing the output beam of said first laser diode at a said compact disk when carried by said disk support and drive means or directing the output beam of said second laser diode at a said digital versatile disk when carried by said disk support and drive means,a single element objective lens optically positioned between said disk support and drive means on one end and said first and second laser diodes on another end,said single element objective lens having a central aperture zone and an outer aperture zone, said central aperture zone being profiled to operate at a first numerical aperture (NA) and said output beam of said first laser diode being optically confined to said central aperture zone,said outer aperture zone together with said central aperture zone being profiled to operate at a second numerical aperture (NA) and wherein said output beam of said second laser diode has ray fans extending across the full aperture of said lens, anddiffractive means carried by said single element objective lens, said diffractive means providing sufficient aspheric surface power for spherical aberration correction and providing correction for spherochromatism.