| 摘要 |
PROBLEM TO BE SOLVED: To provide an object lens and an optical pickup device which are interchangeable without using diffraction to plural kinds of optical information recording media having the transparent substrates different in thickness and perform recording and/or reproducing by correcting a spherical aberration when transparent substrates of the optical information recording media are different in thickness. SOLUTION: The object lens is provided with a refractive lens 2 and a different material layer 1 which is joined to at least one side lens surface of the refractive lens and has material different from that of the refractive lens. Luminous fluxes exited from light sources having different wavelengths are condensed on an information recording surface via the transparent substrate of the optical information recording medium, and recording and/or reproducing are performed to plural kinds of optical information recording media having the transparent substrates different in thickness. |
