| 摘要 |
PURPOSE:To easily measure the eccentricity and surface waving of an optical disk by focusing information track light of a pregroove or wobbling pits formed on the substrate of the optical disk. CONSTITUTION:An optical head 105 fallows up a light spot an information track on the optical disk substrate 101 through an objective 102 and a lens actuator 103. Light transmitted through this substrate 101 is made incident on two photodetection parts 104 arranged oppositely to the objective. Then signals from the photodetection parts 104 are supplied to a differential amplifier 107 to generate an eccentricity signal 109 and a surface waving signal 110 through the other summing amplifier 108. The signals which are obtained actually do not correspond to the extents of eccentricity and waving, so they need to be corrected. For the purpose, the actual quantities of the eccentricity and waving are measured quantitatively by a prescribed system. |
