Patent ID: 8345530

Claim:
An objective lens configured to focus a first laser beam having a first wavelength on an information recording layer of a first optical disc, to focus a second laser beam having a second wavelength longer than the first wavelength on an information recording layer of a second optical disc having a coating layer thicker than that of the first optical disc, and to focus a third laser beam having a wavelength longer than the first and second wavelengths on an information recording layer of a third optical disc having a coating layer thicker than those of the first and second optical discs, the objective lens comprising a center region provided at and around a center portion of the objective lens, and configured to focus the first laser beam, the second laser beam and the third laser beam respectively on the information recording layers of the first optical disc, the second optical disc and the third optical disc, wherein the center region is set to have a surface shape including an annular zone step having a step amount calculated on the basis of only one wavelength, the first wavelength of the first laser beam being the only one wavelength, and the surface shape causing aberrations of both of the first laser beam and the second laser beam.