| 摘要 |
<P>PROBLEM TO BE SOLVED: To provide: an objective lens being applicable to an optical pickup unit for recording and/or reproducing information on a plurality of types of optical information recording media using luminous fluxes having different wavelengths, and having low wavelength dependency of spherical aberration; an optical pickup unit using the objective lens; and an optical information recording and reproducing unit having the optical pickup unit mounted thereon. <P>SOLUTION: On one surface of the lens having power, the objective lens for use in the optical pickup unit has an overlaid structure having: a first optical path difference addition structure, which produces varied spherical aberration in the correction shortage direction when the wavelength of an incident luminous flux is made to have a longer wavelength; and a second optical path difference addition structure, which produces varied spherical aberration in the correction excess direction when the wavelength of an incident luminous flux is made to have a longer wavelength. <P>COPYRIGHT: (C)2010,JPO&INPIT |
