| 摘要 |
PURPOSE: To control variations of a light-receiving position on a light-receiving element caused by variations of a light source wavelength, in a two-light source type optical pickup device which receives laser beams different in wavelength by a common light-receiving element. CONSTITUTION: In the optical pickup device, a laser beam of 650 nm and a laser beam of 780 nm are emitted from light emitting points existing in a position deviated in the direction orthogonal to the optical axis by two-wavelength light sources. Return light L1r, L2r, reflected by the recording surface of an optical recording medium, is diffracted by a diffraction-type element 10. Return light L1r, L2r is guided to the common light-receiving element 11 as +1st order diffracted ray L1r (+1), +2nd order diffracted ray L2r (+2) respectively. The deviations of the light-receiving position on the common light-receiving element 11, caused by the variations of the light source wavelength, is reduced and reproducing/recording performance is stabilized by diffracting both the return light by different diffraction orders.
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