| 摘要 |
<P>PROBLEM TO BE SOLVED: To provide an optical head device and an optical disk drive, by which a magnitude of focus error at the time of recording the information to an optical disk of HD, DVD specification or reproducing the information therefrom is exactly detectable. <P>SOLUTION: This optical head device 11 includes a diffraction element (HOE) 24 furnished with a diffractive pattern capable of providing such a light spot that the fluctuation of focus error mainly containing a component in the radial direction among reflection laser beams reflected by the optical disk is hardly to occur, on a light receiving face of a photodetector 28 for receiving the reflection laser beams reflected by a recording layer of the optical disk to output a corresponding signal. The diffraction element includes at least an area linearly specified in the radial direction. <P>COPYRIGHT: (C)2006,JPO&NCIPI |
