Patent Number: 7,787,332

Title: Optical information recording-reproducing apparatus

Abstract: An optical information recording-reproducing apparatus comprising a light source, an objective lens for condensing a light beam from the light source on a recording layer of an optical recording medium, a divergence angle-converting element provided in an optical path from the light source to the optical recoding medium for converting a divergence angle of the light beam to be introduced to the objective lens, a focus error detecting optical system including a photodetector for detecting a focus error of the light beam, an optical element for introducing a part of the light beam emitted from the divergence angle-converting element to the focus error detecting optical system, a circuit for detecting the divergence angle of the light beam emitted from the divergence angle-converting element from output from the photodetector, and a circuit for compensating spherical aberration in the recording layer of the optical recording medium by driving the divergence angle-converting element in accordance with the detection result of the divergence angle-detecting circuit.

Inventors: Nagura; Chihiro (Kawasaki, JP)

Assignee: Canon Kabushiki Kaisha

International Classification: G11B 7/00 (20060101)

Expiration Date: 8/31/12018