| 摘要 |
<p>An optical pickup apparatus for recording and/or reproducing information of an optical information recording medium, comprising an objective lens (3),
a light source emitting a light flux having a wavelength not more than 500 nm (11),
a spherical aberration deviation correcting unit (4,5,7) comprising a positive lens group (4), a negative lens group (5), and a moving device (7),
wherein at least one of the positive lens group and the negative lens group comprises a movable element movable by the moving device in a direction of an optical axis of the optical pickup apparatus, and the movable element changes the slope angle of the marginal ray of an exit light flux by moving in a direction of the optical axis; and
wherein the objective lens satisfies the following formula:
0.7 ≤ d/f ≤ 2.4,
where d represents an axial lens thickness whose unit is mm and f represents a focal length for the light flux having wavelength λ1 whose unit is mm.
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