OBJECTIVE LENS OF OPTICAL PICKUP AND OPTICAL PICKUP

摘要

In order to provide an optical pickup and an objective lens for the optical pickup which can record/reproduce information on/from an optical information recording medium regardless of temperature variation, temperature characteristics are enhanced to satisfy the following relation; |dSA3<SUB>obj</SUB>/dT|=0.002(?rms/°C). Consequently, even in the case of an objective lens having wavelength characteristics deteriorated to such an extent as satistying the following relation; 0.1>|dSA3<SUB>obj</SUB>/d?|=0.01(?rms/nm), information can be recorded and/or reproduced appropriately regardless of variations in the oscillation wavelength of semiconductor laser or variations in environmental temperature, because the objective lenses are classified according to diffraction structures of different specifications and used in combination with the oscillation wavelength of actual semiconductor laser.