| 摘要 |
<P>PROBLEM TO BE SOLVED: To carry out servo tracking by the three-beam method for both CDs and DVDs. <P>SOLUTION: This pickup has a light source whose package contains a first and second semiconductor laser units, a first diffraction grating to split the laser beam emitted by the first semiconductor laser into three beams, and a second diffraction grating to split the laser beam emitted by the second semiconductor laser into three beams. It also has a diffraction grating unit disposed in one body on the surface where the first and second diffraction gratings face each other, a beam splitter inputted with the laser beams emitted from the first and second semiconductor laser units, an objective lens to form a light spot on the disc by focusing the light reflected by the beam splitter, and a photo acceptance element to convert the light reflected on the disc into electric signals. <P>COPYRIGHT: (C)2003,JPO |
