| 摘要 |
A liquid crystal lens element capable of finely adjusting focal length according to the magnitude of applied voltage, and an optical head device employing such a liquid crystal lens element, are provided. On one surface of a transparent substrate 511 , a transparent electrode 513 and a concave-convex portion 517 made of a transparent material having a cross section shape approximated by a saw-tooth shape, are formed so as to constitute a plurality of annular portions, and on one surface of a transparent substrate 512 , a transparent electrode 514 is formed. The transparent electrodes 513 and 514 constitute annular divided electrode segments, and division positions of the annular electrode segments are made to be agree with division positions of annular portions of the saw-tooth-shaped concave-convex portion 517 of the transparent substrate 511.
|
