| 摘要 |
<P>PROBLEM TO BE SOLVED: To form a favorable spot on an information recording plane of a blue system optical recording medium, a DVD system optical recording medium, or a CD system optical recording medium without increasing the number of parts. <P>SOLUTION: A liquid crystal element for correcting spherical aberration is constituted by forming metallic electrodes 12a-14a, 12b-14b on transparent electrodes 10a, 10b with a pair of continuous transparent electrodes 10a, 10b as a unit. A metallic electrode 13a is formed at a pupil radius position where the spherical aberration generated when recording and reproducing the DVD system optical recording medium is a maximum, and a metallic electrode 13b is formed at a pupil radius position where the spherical aberration generated when recording and reproducing the CD system optical recording medium is a maximum. Voltage is applied to the metallic electrode 13a at the position where an additive phase amount is maximized in recognizing the insertion of the DVD system optical recording medium of an optical recording medium discrimination means to the liquid crystal element, and voltage is applied to the metallic electrode 13b at the position where an additive phase amount is maximized in recognizing the CD system optical recording medium. Moreover, in the recognition of insertion of a blue optical recording medium, the liquid crystal element does not play any role at all. <P>COPYRIGHT: (C)2004,JPO |
