Patent ID: 7158454

Claim:
An optical device, which comprises: a first light source, providing a first polarized light needed when picking up signals; a first beam splitter, reflecting said first polarized light; a first objective lens, focusing said first polarized light reflected by said first beam splitter to a disc and completing a first emergent light path; a photo detector, detecting signals carried by said first polarized light, and passing through said first objective lens and said first beam splitter after being reflected by said disc, and further entering the photo detector, to complete the first light loop; a second light source, providing a second polarized light needed when picking up signals; a second beam splitter, reflecting said second polarized light; and a second objective lens, focusing said second polarized light reflected by said second beam splitter on said disc and completing said second emergent light path, wherein after being reflected by said disc, said second polarized light passes through said second objective lens, and is reflected by said second beam splitter and said first splitter, and therefore enters said photo detector to be detected with the signals carried, in order to complete the second light loop.