Patent ID: 7099260

Claim:
An objective lens for an optical disk comprising a single lens focusing light beams into a point image through first and second optical disk substrates each having a different thickness, at least one surface of the objective lens being divided into at least three regions by concentric circles having an optical axis as a center, the three regions including: a first region, including the optical axis, that is a rotationally symmetric aspheric surface; a second region that is a rotationally symmetric aspheric surface; and a third region, sandwiched by the first region and the second region, that is a toric surface having the optical axis as an axis of rotation and is in contact with the second region and intersects the first region, wherein, the light beam incident on the third region substantially does not form the point image through the first and second optical disk substrates, wherein, when the first region and the second region are extended respectively toward each other, an extended portion of the first region and an extended portion of the second region have a distance between each other in a direction of the optical axis, at a position having the same height from the optical axis, corresponding to the third region.