| 摘要 |
A laser light beam of a first wavelength which is polarized in a first polarizing direction, emitted from first and second semiconductor laser elements and reflected by an information recording surface of an optical recording medium, is made to be transmitted by a second polarizing hologram diffraction grating and diffracted in a direction toward a light receiving element by a first polarizing hologram diffraction grating. A laser light beam of a second wavelength which is polarized in the first polarizing direction, reflected by the information recording surface of the optical recording medium, is made to be converted so to be in a second polarizing direction by the 5lambda/4 plate. A laser light beam of the second wavelength which is polarized in the second polarizing direction is made to be diffracted in the direction toward the light emitting element by the second polarizing hologram diffraction grating.
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