| 摘要 |
An object of the present invention is to provide an optical head apparatus having a high signal to noise ratio in an RF signal in a simple circuit configuration, and an optical information recording or reproducing apparatus that uses it. The optical head apparatus includes a light source, an objective lens configured to focus an output light beam from the light source onto a disc-shaped optical recording medium, and a light detecting unit configured to receive a reflection light beam from the optical recording medium, and further includes an optical diffraction element configured to separate said reflection light beam into a first light beam group and a second light beam group, wherein the optical diffraction element generates the first light beam group from an entire section region of the reflection light beam and said second light beam group from at least a part of the section region of the reflection light beam. The light detector receives the first light beam group and the second light beam group by different light receiving sections, in order to detect a track error signal used for a track servo and a radial tilt signal indicating the radial tilt of the optical recording medium.
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