| 摘要 |
PROBLEM TO BE SOLVED: To secure full recording and/or reproducing properties for a plurality of types of optical disks without being affected by chromatic aberration due to differences of laser beams of a different wavelength. SOLUTION: The device is equipped with a first and a second semiconductor laser 21, 22 that emit a laser beam of the first and the larger-than-the-first second wavelength respectively, an objective lens 17 that converges the outgoing light of the first and the second wavelength each emitted from these first and the second semiconductor laser 21, 22 on a plurality of types of optical disks 4, and a phase mask 16 that is arranged at a position on an optical path between the first semiconductor laser 21 and the objective lens 17 and that imparts to a transmitting beam a phase difference pattern having stripes parallel to the direction orthogonal to the polarization direction of the outgoing light from the first semiconductor laser 21. The phase difference by the phase mask 16 is made integer times the wavelength relative to the outgoing light of the second wavelength and non-integer times the wavelength relative to the outgoing light of the first wavelength. |
