| 摘要 |
Optical pickup head comprises two semiconductor lasers for irradiating first to third optical beams, light receiving element for converting an optical signal into an electrical signal, and object lens unit. Object lens unit includes first object lens (object lens for CD, DVD, and HD-DVD) and second object lens (object lens for Blu-ray Disc) having a numerical aperture different from first object lens. First object lens and second object lens are moved in a tangential direction or in a radial direction of recording medium, so that first object lens and second object lens can be selectively arranged opposite to a position to be irradiated with the optical beam of recording medium.
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