| 摘要 |
An optical pickup system for reproducing an information signal stored on an optical disk, including a pair of recording surfaces thereon, is provided with a pair of light sources for generating a first and a second light beams having different wavelength, lambda 1, lambda 2, a detector, an objective lens, a signal detection unit and a beam splitter having a first and a second surfaces, wherein the first surface of the beam splitter is pervious to the light beam having a wavelength other than lambda 1 and the second surface of the beam splitter is pervious to the light beam having a wavelength other than lambda 2. In the system, while the first light source is used for reproducing the information signal off the first recording surface of the optical disk, the first light beam transmitted from the second surface of the beam splitter is used for detecting the focusing error signal of the first recording surface of the optical disk. When the second light source is used for detecting the focusing error signal of the second recording surface of the optical disk, the second light beam reflected from the second surface of the beam splitter is utilized for reproducing the information signal off the second recording surface with the first light source turned off.
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