| 摘要 |
A multiple wavelength-adaptive optical pickup according to the present invention enables to obtain stable signals by suppressing displacement of optical intensity distribution at a light receiving section. When an incident angle of a central beam of a zero-dimensional beam of a beam reflected at an optical disc into a half mirror is taken as &thetas;, if variation in transmittance of the mirror become a maximum with respect to change in the incident angle from &thetas; to a plus side in any one of the wavelengths corresponding to the respective optical discs, a −1 dimensional beam generated on the minus side with respect to the zero-dimensional beam is received by the light receiving section, and if the variation in the transmittance of the mirror become the maximum with respect to change in the incident angle from &thetas; to the minus side, a +1 dimensional beam generated on the plus side with respect to the zero-dimensional beam is received by the light receiving section. These received one-dimensional beams are used for detection of signals for servo control.
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