| 摘要 |
PROBLEM TO BE SOLVED: To provide an optical pickup, equipped with a chromatic aberration correcting element which corrects focal positional deviation due to the wavelength fluctuation in a semiconductor laser, in the optical pickup that is capable of recording on and reproducing from an optical disk having a capacity of 20-25 GBs and that is equipped with a blue semiconductor laser and a high NA objective lens. SOLUTION: The chromatic aberration correcting element, consisting of a diffraction optical element and a concave lens, is provided in an optical system between the objective lens and the semiconductor laser. The focal distance of the diffraction optical element is set between 30 and 45 mm. |
