| 摘要 |
In an optical pickup used in a DVD player, a photo detector has a predetermined photo sensing area pattern for detecting a returning laser beam from an optical disc. The returning laser beam is originated from a first laser beam or a second laser beam. The first and the second laser beams are alternatively emitted from a two wavelength laser having first and second right sources. Either the first laser beam or the second laser beam travels to the optical disc through a grating, a polarizing beam splitter, a collimating lens, a rising mirror, and an object lens and is reflected by the optical disc. The reflected laser beam reflected from the optical disc travels to the photo detector as the returning laser beam through the object lens, the rising lens, the collimating lens, and the polarizing lens. The predetermined photo sensing area pattern enables the photo detector to detect the returning laser beam regardless of the origin of the returning laser beam.
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