| 摘要 |
PROBLEM TO BE SOLVED: To set the light source position of an optical pickup by one light receiving element by setting the arrangement relation between two light sources so that respective light beams from the two light sources are guided to one pair of light receiving part sets by a diffraction element. SOLUTION: Light beams emitted from two light sources 11, 12 transmit a diffraction grating for three beams 17, a hologram element 18, a polarization dependent grating lens 13 and an objective lens 14 to be condensed on recording layers 15a, 16a of an optical disk 15 or an optical disk 16. Reflected light beams reflected on the recording layers 15a, 16a of the optical disk 15 or the optical disk 16a reach the hologram element 18 through the lenses 14, 13. Then, the light beams are respectively diffracted with angles depending on their wavelengths by the element 18 to be guided to a light receiving part 20, which has a light receiving part set 20a consisting of six light receiving parts. The quadripartite light receiving parts of a central part receive main spots in three beams and two light receiving parts of both sides of the parts receive two subspots in the three beams. |
