| 摘要 |
According to one embodiment, an optical head unit of the invention combines preferably and simplifies a diffraction pattern of a diffraction element to guide a reflected laser beam divided into a predetermined number to a photodetector, in order to provide an optical head unit and an optical disc apparatus which provide a stable reproducing signal irrespectively of the standards of recording media, when reproducing information from a recording medium of optional standard. By using the combined and simplified diffraction pattern, the optical head unit easily provides outputs usable to detect first, second and third signals used to detect a tracking error when reproducing information recorded on an optical disc from a reflected laser beam from an optical disc, a fourth signal used to detect a focus error, and a fifth signal used to detect a spherical aberration compensating component.
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