| 摘要 |
<P>PROBLEM TO BE SOLVED: To provide a low-cost optical head for which easy optical design is required and an optical recording and reproducing device using it. <P>SOLUTION: A grating surface of a polarization hologram element 12 for DVD has six regions obtained by dividing an area in a contour line of a circular shape by four dividing lines 11-14. An optical path change region F1 and an optical path change region F2 are arranged in the direction of an arrow mark T apart for a straight dividing line 12, and a part of 0th order light for return path is made incident. The 0th order light transmitted through the optical path change region F1 and the 0th order light transmitted through the optical path change region F2 are changed respectively to a separated optical path, and made incident on different light receiving planes in an optical detector for DVD/CD. The 0th order light transmitted through the optical path change region F1 and the 0th order light transmitted through the optical path change region F2 are used for generating a focus error signal. <P>COPYRIGHT: (C)2005,JPO&NCIPI |
