| 摘要 |
The present invention provides a construction that can obtain tracking error signals suitably from any of the optical disks having differing track pitch by reducing the main spot size in an optical recording disk apparatus which reads and retrieve information on an optical recording disk. In the optical recording apparatus, diffraction element 8 for 3-beam generation increases the rim intensity of zero-order beam by decreasing the intensity of the zero-order beam in inner diffraction region 81 to decrease the size of the main spot. Additionally, between optical recording disks of the DVD system and the CD system which retrieve and record information on the optical recording disk apparatus, the optical system is configured such that the sub-spot is centered at the location shifted from the center of the main spot in the tracking direction at a distance of 0.25 times the track pitch.
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