| 摘要 |
<P>PROBLEM TO BE SOLVED: To provide an optical pickup which can obtain excellent reproduction signals by further reducing the residual error in correcting the spherical aberrations by phase shifting. <P>SOLUTION: The liquid crystal element 6 has a pair of transparent panels 21, 22, liquid crystals 23 filled between those panels, a diffraction pattern 24 composed of concentric diffraction electrodes 24a-24c formed on one panel 21, and a phase shift pattern 25 composed of concentric phase shift electrodes 25a-25c formed on the other panel 22. The diffraction pattern 24 has a first area X1 radially within a certain range from the center with large electrode gap, an outside second area X2 with small electrode gap, and a further outside third area X3 with a single diffraction electrode. Additional electrodes 26 are formed facing the phase shift electrodes 25a in the spaces between the diffraction electrodes 24a in the area X1. <P>COPYRIGHT: (C)2008,JPO&INPIT |
