Optical pickup device
OwnerRyo Saitoh, Makoto Itonagainventors
Life of this patent
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Abstract
First order diffraction lights reflected on a first signal face for reproducing an optical disc and further deflected by a spatial divide element converge to spots 21a to 21d on photo acceptance cells 9A to 9D of a photodetector 9, while diffraction lights reflected on the first signal face and further diffracted by other orders of diffraction except plus first-order and diffraction lights reflected on a second signal face become crosstalk lights. Therefore, an optical pickup device is adapted so that minus (−) first-order diffraction lights 23a to 23d from the first signal face and the spots 21a to 21d of the first order diffraction light from the second signal face are not radiated on the photo acceptance cells 9A to 9D.
Claims9
An optical pickup device comprising:
- a laser source for emitting laser beams;
- a collimator lens for converting the laser beams emitted from an emission point of the laser source to substantially-parallel lights;
- an objective lens that converges the substantially-parallel lights to form spots on a first signal face or a second signal face of an optical disc;
- a spatial divide element having a plurality of parting lines arranged so as to run on a substantial flux center of a reflection light from the first signal face or the second signal face and a plurality of areas defined by the parting lines to thereby deflect the reflection light to predetermined directions respectively;
- and
- a photodetector receiving signal detection lights diffracted in the predetermined directions and applied with astigmatisms by the areas of the spatial divide element and including a plurality of photo acceptance cells arranged in positions where the signal detection lights form a circle of least confusion at a substantial midpoint of two focal lines produced due to the astigmatisms, the photo acceptance cells corresponding to the plurality of areas respectively.
Dependencies are inferred from the claim text.