| 摘要 |
<p>In order to provide an optical pickup device that can reduce the amount of movement of a coupling lens, is compact and low cost, is favorable in a slimline form, and can perform recording of data to and playback of data from an optical disc having a multi-layered data recording surface, the optical pick up device has a light source, a coupling lens, and a single objective lens, the object-side numerical aperture of which is at least 0.8 and no more than 0.95; the coupling lens has one mobile lens; by means of moving the mobile lens between the light source and the objective lens in the direction of the light axis, a data recording surface is selected; and when considering the maximum transparent substrate thickness to be TMAX, at room temperature and with a cover glass thickness of T that satisfies formula 1, the magnification power (M) when spherical aberration is minimized satisfies formula 2: TMAX × 0.80 = T = TMAX × 1.1 (1) -0.003 = M = 0.003 (2)</p> |
