| 摘要 |
PROBLEM TO BE SOLVED: To provide an information pickup device which is capable of reproducing plural optical disks having different substrate thicknesses with one optical pickup, has interchargeability with each other, is simple in structure and is made compact by previously this device with a divergence degree changing means for changing the divergence degree of the incident luminous flux on an objective lens. SOLUTION: This information pickup device has a laser beam source 1, a beam splitter 2 and the objective lens 6 having the positive refracting power for condensing the luminous flux from the laser beam source 1 past the beam splitter 2 onto an information recording surface 8 via a transparent substrate 7 of an optical information recording medium and has a receiving means for receiving the luminous flux past the beam splitter 2. Further, the device is provided with the divergence degree changing means consisting of a lens 3 and a lens moving means 21 as an example, by which the divergence degree of the incident luminous flux on the objective lens 6 is changed according to the thickness of the transparent substrate 7. |
