Patent ID: 8432782
Filing Date: 2013-04-30
Classification: G02B,G11B

Abstract:
1. An objective lens for converging a laser beam emitted from a laser light source on an information recording surface of an information recording medium, the objective lens comprising: a first area which has a diffraction structure which is formed on a surface on the laser light source side; a second area which has a diffraction structure which is formed outside the first area; and a third area which has a diffraction structure which is formed outside the second area, wherein the first area and the third area converge a laser beam having an order of diffraction with which diffraction efficiency is highest, out of laser beams having a wavelength λ the first area and the second area converge a laser beam having an order of diffraction with which diffraction efficiency is highest, out of laser beams having a wavelength λ the diffraction efficiency of the laser beam having the wavelength λ the second area does not converge a laser beam having an order of diffraction with which diffraction efficiency is highest, out of the laser beams having the wavelength λ