Patent Number: 7,787,349

Title: Optical pickup lens and optical pickup apparatus

Abstract: An optical pickup lens focuses laser beams having different wavelengths .lamda.1, .lamda.2 and .lamda.3 on at least three kinds of optical discs. At least one side of the optical pickup lens has a concentric loop zonal structure for compensating wavefront aberration occurring when recording or reproducing an optical disc having a substrate thickness t1 by the laser beam having the wavelength .lamda.1 and wavefront aberration occurring when recording or reproducing an optical disc having a substrate thickness t2 by the laser beam having the wavelength .lamda.2. When recording or reproducing an optical disc having a substrate thickness t3 by the laser beam having the wavelength .lamda.3, a phase difference given to the laser beam having the wavelength .lamda.3 due to the concentric loop zonal structure is about 0.15.lamda. or smaller.

Inventors: Wakabayashi; Koichiro (Ibaraki, JP), Miyauchi; Mitsuhiro (Ibaraki, JP), Sugi; Yasuyuki (Ibaraki, JP), Makino; Yutaka (Ibaraki, JP)

Assignee: Hitachi Maxwell, Ltd.

International Classification: G11B 7/00 (20060101)

Expiration Date: 8/31/12018