| 摘要 |
An optical pickup device capable of accessing, using one pickup device, two opposed discs without turning the pickup device over. The pickup device includes a light source; a beam splitter for dividing a beam into two linearly polarized beams, a reflecting prism for making the two linearly polarized beams parallel, a total reflection prism for concurrently receiving the two parallel beams and reflecting the light upwards and downwards, respectively; upper and lower quarter-wavelength plates for converting the two respective beams into circularly polarized beams, objective lenses which are movable in horizontal and vertical directions by focusing and tracking coils for focusing the light on the optical discs and for returning reflected light therefrom to the total reflection prism, respectively; a partial reflection prism for transmitting a portion of the incident light but reflecting the remaining portion of the incident light; a tracking optical detector for detecting and converting the light transmitted through the partial reflection prism into an electric signal; and a focusing optical detector for detecting and converting the light, reflected by the half prism, into the form of an electric signal. Either the upper or lower optical disk is accessed by defocusing the focus of the beam incident on the other disc.
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