| 摘要 |
A light source, an objective lens which concentrates light from the light source onto an information recording surface of an information storage medium, and a spherical aberration correction mechanism provided on a light path between the light source of the objective lens are provided. The spherical aberration correction mechanism includes a piezoelectric element for moving a coupling lens, a photo interrupter which detects whether the coupling lens has been moved to an initial position, and a spherical aberration correction element control circuit which moves the coupling lens, which has been moved to the initial position, to one of first to n-th (n is an integer not less than 2) positions where light is concentrated onto an information recording surface of one of first to n-th layer of the information storage medium, the distances between the initial position to the respective first to n-th positions having been determined in advance. With this, it is possible to provide an optical pickup device which can stably perform focus control and spherical aberration correction, without increase in the number of photo interrupters.
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