| 摘要 |
It is possible to provide an optical pickup device having a comparatively simple configuration and capable of recording and/or reproducing information in a compatible manner with respect to a different optical information recording medium. A first objective lens (OBJ1) and a second objective lens (OBJ2) have optical surfaces formed only by a refractive surface. Furthermore, the first objective lens (OBJ1) can be designed with optimization for a first light flux of wavelength U1 and a protection layer (t1) of an optical disc (OD1). On the other hand, a second objective lens (OBJ2) is shared by the first light flux of the wavelength U1 and a second light flux of wavelength U2. When a protection layer (t2) of a second optical disc (OD2) is identical to a protection layer (t3) of a third optical disc (OD3), there is no need of considering a difference between the protection layer thicknesses, which facilitates design and reduces the cost. It should be noted that the color aberration based on a wavelength difference between the first light flux and the second light flux can be corrected by displacing a second coupling lens (COL2) so as to change the diversion angle to the second objective lens (OBJ2). |
