RECORDING AND/OR REPRODUCING DEVICE

摘要

PROBLEM TO BE SOLVED: To achieve a high recording density and a large capacity of an optical disk by reducing the generation amount of spherical aberration even if the numerical aperture NA of an objective lens loaded on an optical head is increased.

SOLUTION: An optical head 1 used for recording/reproducing in an optical disk 2 including a light transmitting layer 4 formed on a recording layer includes an actuator 14 for a collimator lens. A collimator lens 13 is moved between a light source 10 and an objective lens 16 to cancel spherical aberration caused by thickness errors of the light transmitting layer 4 by the actuator 14 for the collimator lens. In this case, the collimator lens 13 is moved to a position calculated so that a square average of wave surface aberration is minimum corresponding to thickness errors of the light transmitting layer beforehand according to the value obtained from a thickness detection means.

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