| 摘要 |
<P>PROBLEM TO BE SOLVED: To provide an objective lens unit used for compatible use, for which the risk of deterioration in image formation accuracy due to the influence of a tracking coil and a focusing coil is suppressed. <P>SOLUTION: Since a holder 30 supports the side of a second lens part 22 for allowing a relatively large spot diameter (for DVD or CD) of a compound objective lens 20, even when the holder 30 is heated by the high load operation of the tracking coil and the focusing coil, the heating does not easily affect on a first lens part 21 where highly accurate image formation is required. That is, since the first lens part 21 of a high requirement level relating to a using environment or the like is operated under a relatively advantageous environment and a relatively small first spot diameter formed of the laser beam of a wavelength 405nm for BD is surely maintained with high reliability, high image formation accuracy and information reproducing and recording accuracy are secured. <P>COPYRIGHT: (C)2007,JPO&INPIT |
