| 摘要 |
PURPOSE: An optical pick-up apparatus is provided to effectively correct a spherical aberration generated in an optical surface of each optical pick-up apparatus with a simple structure change, and to correct an axial chromatic aberration caused by mode hopping of a semiconductor laser and HFCS(High Frequency Superimposition). CONSTITUTION: An optical pickup apparatus(23) for conducting recording and reproducing information of an optical information recording medium, is composed of a light source(11), a converging optical system and photo-detectors(41,42). The converging optical system has an objective lens(3) converges optical flux irradiated from the light source on an information recording plane(5) of the optical information recording medium, so as to conduct recording and reproducing information of the optical information recording medium. The photo-detectors accept the optical flux reflected from the information recording plane. The converging optical system is composed of the plastic lens(3) and spherical aberration deviation correcting elements(4,5) to correct deviation of a spherical aberration of the converging optical system. And a numerical aperture of the objective lens at an image-side is 0.65 or more.
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