| 摘要 |
<P>PROBLEM TO BE SOLVED: To more easily and accurately control a distance between an objective lens and a relay lens constant, by optically detecting the error of the distance between the objective lens and the relay lens from an ideal distance. <P>SOLUTION: The ideal focal position of recording/reproducing light of a hologram is set, at a position closer to an objective lens side than the lower layer side of a recording layer which is a conventional ideal focal position. A marker light is generated at a position away from an optical axis and, based on a difference between the ideal receiving position of the marker light and the actual receiving position of the marker light, and the distance between the objective lens and the relay lens is adjusted (controlled). Thus, the difference between the distance between the objective lens and the relay lens and the ideal distance is detected optically and based on the result, fixed distance control between the objective lens and the relay is performed more easily and more accurately. <P>COPYRIGHT: (C)2011,JPO&INPIT |
