| 摘要 |
<P>PROBLEM TO BE SOLVED: To provide a liquid crystal device being easily used for an optical pickup that corrects higher-order components of spherical aberration with a liquid crystal device of a simple configuration, and has a control mechanism of a focal position. <P>SOLUTION: A first transparent electrode 24 is formed at a side of a liquid crystal layer 23 of a first transparent substrate 21 such that the electrode covers all regions of an incident area of a beam. Also, an opening electrode 25 having an opening in the center is formed at a side opposite to the liquid crystal layer 23 of a second transparent substrate 22. In this case, when it is assumed that the opening diameter of an opening electrode 25 is D and the thickness of the second transparent substrate 22 is t1, a liquid crystal device 11 is configured so as to satisfy 7<D/t1<40. Thus, spherical aberration being high in coincidence with a theoretical formula of higher-order components of spherical aberration is corrected without dividing the first transparent electrode 24 and the opening electrode 25. Moreover, aberration correction and a focal point are separately controlled by providing only aberration correction capability in the liquid crystal layer 23. <P>COPYRIGHT: (C)2007,JPO&INPIT |
