| 摘要 |
<P>PROBLEM TO BE SOLVED: To provide a laser condenser, an optical pickup device, and an optical disk recording/reproducing device using laser light of the same wavelength and capable of being commonly used for optical disk media having different thicknesses of protective layers. <P>SOLUTION: There are provided: a polarization hologram element having a first region of a numerical aperture conforming with the thickness of the first protective layer of the first disk medium and a second region in the first region having a numerical aperture conforming with the thickness of the second protective layer (larger than the thickness of the first protective layer) of the second disk medium and having a hologram pattern transmitting first laser light linearly polarized in a first direction and diffracting and transmitting second laser light having the same wavelength and linearly polarized in a second direction perpendicular to the first direction; an objective lens which condenses the first laser light transmitted through the first region with the second region having the numerical aperture conforming with the thickness of the first protective layer onto an information surface of the first protective layer and condenses the second laser light transmitted through the second region onto an information surface of the second protective layer; and a holder for holding the polarization hologram element and the objective lens. <P>COPYRIGHT: (C)2007,JPO&INPIT |
