| 摘要 |
PROBLEM TO BE SOLVED: To avoid the collision of an optical disk and a pickup in the case that the working distance of both is short, to cope with the small-sized objective lens of high NA and to accelerate focus control. SOLUTION: A position change mechanism 11 changing the focus position of a laser beam is provided on the surface not facing an optical disk surface of the objective lens and a focus position control part 12 changes the focus position stepwise through the focus position change mechanism 11. Then, a focus direction movement control part 14 brings the optical pickup including the objective lens closer to the optical disk surface stepwise while monitoring the peak of focus error signals by a peak detection part 13 and performs the zero cross control of the focus error signals at the point of time of detecting the focus position. |
