| 摘要 |
PROBLEM TO BE SOLVED: To provide an optical pickup device capable of recording and/or reproducing information on different optical information recording media by using a relatively long wavelength single light source without using any additional electric circuits, and an objective lens used for the same. SOLUTION: Since the wavelength λ of a light source exceeds 700 nm, for example even when a CD-R or a CD-RW is used, information recording or reproducing is effectively executed. On the other hand, when a DVD is used, there is a danger that in the case of the light of a wavelength λ exceeding 700 nm, a light quantity necessary for information recording or reproducing becomes short. Thus, by heightening a numerical aperture NA to be more than 0.65, a sufficient light quantity is obtained. As for the deterioration of spherical aberration caused by a difference in thickness between the transparent substrate of the DVD and that of a CD, by dividing an optical surface into a plurality of functional areas, optical balance is obtained. |
