| 摘要 |
<P>PROBLEM TO BE SOLVED: To solve the problem wherein the difficulty in setting a spot interval to a half of a guidance groove pitch, when a BD and a HD DVD share a diffraction grating for 3-beam generation, as guiding groove pitches of optical disks are different between the BD and the HD DVD, when the BD and the HD DVD both use a DPP method as a tracking error signal detection method, in an optical pickup where the BD and the HD DVD are compatible to each other. <P>SOLUTION: The spot interval S<SB>1</SB>of 3 beams on a BD-R/RE is set smaller than the spot interval S<SB>2</SB>of 3 beams on an HD DVD-R/RW. Alternatively, the lateral magnification M<SB>1</SB>of a BD optical system is set larger than the lateral magnification M<SB>2</SB>of an HD DVD optical system; and Equations 1 and 2 are satisfied, if T<SB>1</SB>is the guidance pitch of BD-R/RE and T<SB>2</SB>is the guidance pitch of the HD DVD-R/RW. <P>COPYRIGHT: (C)2008,JPO&INPIT |
