OPTICAL DISK DEVICE AND FOCUSING CONTROL METHOD OF OPTICAL DISK DEVICE

摘要

PROBLEM TO BE SOLVED: To improve precision of focus control by moving an objective lens in the optical axis direction based on the detecting result of a light quantity of interference light between reflecting light reflected with the master disk of a focusing laser beam and reflecting light reflected with the emitting surface of the objective lens. SOLUTION: A focusing laser beam L2 by the wavelength not exposing a master disk 2 different from a recording laser beam L1 is emitted by a laser beam source 18 consisting of a He-Ne laser. The focusing laser beam L2 passes through an objective lens 12 with paraxial light, is respectively reflected with the emitting surface of the objective lens 12 and the surface of the master disk 2, and both reflecting light interfere when the objective lens 12 approaches the master disk 2 to the extent of near-field recording. Interference light L2R generated by interference of reflecting lights is separated with a polarizing beam splitter 20 and is sent to a light receiving element 25. The objective lens 12 is controlled with a control circuit 30 based on the detecting result S2 of the light quantity of the interference light L2R from the light receiving element 25.