Patent ID: 6246041
Filing Date: 2001-06-12
Classification: G11B

Abstract:
An apparatus for measuring focusing characteristics of an optical pickup and/or an optical disc comprising:focusing servo control means for controlling a focal point position of a laser light beam illuminated on the optical disc, based on an output of a photoelectric converting unit of the optical pickup, for focusing the laser light beam on a recording surface of the optical disc;reproducing means for reproducing data recorded on the optical disc based on an output of the photoelectric converting unit of the optical pickup;error rate detection means for detecting an error rate of data reproduced by said reproducing means; andmeasurement means for imparting a pre-set offset amount to a control amount of said focusing servo control means for varying the focusing position of the laser light, getting from said error rate detection means an error rate of reproduced data when the focusing position of the laser light is varied and for finding the focusing position of the laser light corresponding to the minimum error rate in accordance with an equation of approximation of the error rate corresponding to each focusing position of the laser light.