| US 7,595,472 B2 | ||
| Optical head device | ||
| Yuichiro Yamamoto, Tokyo (Japan) | ||
| Assigned to Kabushiki Kaisha Toshiba, Tokyo (Japan) | ||
| Filed on Feb. 27, 2008, as Appl. No. 12/38,587. | ||
| Application 12/038587 is a division of application No. 11/388616, filed on Mar. 24, 2006, granted, now 7,358,471. | ||
| Claims priority of application No. 2005-199140 (JP), filed on Jul. 07, 2005. | ||
| Prior Publication US 2008/0315069 A1, Dec. 25, 2008 | ||
| Int. Cl. G11B 7/00 (2006.01) | ||
| U.S. Cl. 250—201.5 [369/44.24; 369/112.01] | 5 Claims |
| 1. An optical head device which reproduces information recorded in an optical disk including recording layers, comprising:
a light source which emits a light beam, the light source being capable of selectively emitting a high-output light beam and
a low-output light beam;
an objective lens which condenses the light beam on the optical disk;
a condensing lens which condenses reflected light from the optical disk;
a shielding element disposed near a focal point of the condensing lens and having a pinhole, the shielding element including
a transparent substrate and a thin film disposed on the transparent substrate, the thin film being partially melted by application
of the high-output light beam to form the pinhole which passes the reflected light from a reproduction layer of the optical
disk and partially interrupts the reflected light from a non-reproduction layer of the optical disk; and
a photodetector which detects light passed through the pinhole of the shielding element.
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