| 摘要 |
<p>Disclosed is an optical pickup device capable of recording and playing information on optical discs comprising multilayered information recording surfaces, the device minimizing quantity of movement of coupling lenses, and being suitable as a slim type of device, being compact and inexpensive. In the slim type of optical pickup device, setting such that the thickness (T) of the cover glass satisfies the formula (1), and moving a positive lens group in the optical axis direction, from among coupling lenses comprising a negative lens group further comprising a negative refraction and a positive lens group with a positive refraction, under conditions that satisfy the formula (2), allows selecting among three or more information recording layers in recording and playing information. TMAX ° 0.80 = T = TMAX ° 1.1 (1) -0.003 = M = 0.003 (2)</p> |
