| 摘要 |
<P>PROBLEM TO BE SOLVED: To provide an optical head technique suppressing the increase of the number of additional RF signals in PD signals. <P>SOLUTION: This optical head includes a holographic diffraction element (HOE) which is divided into a number of areas and diffracts the reflected light from the optical recording medium to a number of optical detectors (PD) which detect the diffracted light. The focusing area in the HOE crosses the opening in the radial direction of the disk. It uses an area within the circle of the same radius as an opening centering the position separated by 1.5 to 1.6 times the radius of the opening in the radial direction of the disk from the center of the opening of the HOE as the first push-pull (PP) area, and the other focusing area as the second push-pull area, then inputs the light diffracted in the first push-pull area among the divided four areas and the light diffracted in the second push-pull area opposite to those areas and divided into four into the same optical detector out of the optical detectors. <P>COPYRIGHT: (C)2010,JPO&INPIT |
