| 摘要 |
<p>An optical pickup device comprising a first light source emitting a first light beam, a second light source emitting a second light beam, a third light source emitting a third light beam, and an objective optical element, wherein the optical surface of the objective optical element has at least a central region and a peripheral region, the central region has a first optical path difference imparting structure and the peripheral region has a second optical path difference imparting structure, first best focus and second best focus are formed by the third light beam passed through the first optical path difference imparting structure, a spot central part, a spot middle part and a spot peripheral part are formed in a spot which is formed on the information recording surface of a third optical disk by the third light beam passed through the objective optical element, the spot central part is used for recording and/or reproducing the information on the third optical disk but the spot middle part and the spot peripheral part are not used for recording and/or reproducing the information on the third optical disk, and the spot peripheral part is formed on the information recording surface of the third optical disc by the third light beam passed through the second optical path difference imparting structure.</p> |
