| 摘要 |
<p>An optical pickup apparatus for detecting an S-shaped signal of preferable symmetry and acquiring a focus error signal by the SSD method for stabilization of operation. A laser beam is applied to an optical recording medium and at least reflected light from the optical recording medium is introduced via a diffraction element to a photo detector unit. A focus error signal detection is performed by a spot size detection method using the diffraction light generated by the diffraction element. The photo detector unit is located at a position offset to the side of the diffraction element from the focal point position of 0-th degree light which has passed through the diffraction element.</p> |
