Patent ID: 8681592

Claim:
An objective lens element configured for converging each of light of a first wavelength and light of a second wavelength on an information recording surface of an optical disc, the objective lens element comprising; a surface having a first region including an optical axis and a second region surrounding the first region, wherein: a periodic first diffraction structure is provided on the first region, a periodic second diffraction structure, different from the first diffraction structure, is provided on the second region, and | A 1 −B 1 |<|A 2 −B 2| (1), | B 1 |≧|B 2| (2), where: A1 is a diffraction order at the first region to converge the light of the first wavelength on the information recording surface, B1 is a diffraction order at the first region to converge the light of the second wavelength on the information recording surface, A2 is a diffraction order at the second region to converge the light of the first wavelength on the information recording surface, and B2 is a diffraction order at the second region to converge the light of the second wavelength on the information recording surface.