| US RE40,954 E1 | ||
| Objective lens and optical head device | ||
| Tomohiko Sasano, Osaka (Japan); Yasuhiro Tanaka, Hyogo (Japan); and Michihiro Yamagata, Osaka (Japan) | ||
| Assigned to Panasonic Corporation, Osaka (Japan) | ||
| Appl. No. 10/999,236 PCT Filed Jul. 27, 2000, PCT No. PCT/JP00/05040 § 371(c)(1), (2), (4) Date Mar. 27, 2001, PCT Pub. No. WO01/13369, PCT Pub. Date Feb. 22, 2001. |
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| Application 10/999236 is a reissue of application No. 09/806212, filed on Mar. 27, 2001, now 6,490,100, filed on Dec. 03, 2002. | ||
| Claims priority of application No. 11-216281 (JP), filed on Jul. 30, 1999; and application No. 2000-180406 (JP), filed on Jun. 15, 2000. | ||
| Int. Cl. G02B 7/00 (2006.01) | ||
| U.S. Cl. 359—719 [359/708; 359/718; 359/710; 369/112.2] | 21 Claims |
| [ 18. An apparatus for recording information and/or reproducing recorded information on the surface of an optical medium, comprising:
a light source;
an objective lens for focusing a light beam from the light source onto the surface of the optical medium;
a detector for detecting either an inclination of the optical medium or the third-order coma aberration generated based on the inclination;
a light beam splitter for splitting a light beam that has been modulated by the information recording surface of the optical
medium; and
a photodetector for receiving the light beam that has been modulated by the surface of the optical medium, and
an actuator for inclining the objective lens based on either the inclination amount or the third-order coma aberration detected by the detector,
wherein DC/LC>−0.9 is satisfied, where DC (mλ) represents a third-order coma aberration generated when the optical medium is inclined at 0.5° and LC (mλ) represents a third-order coma aberration generated when the objective lens is inclined at 0.5°.]
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