Title:
OPTICAL HEAD
Document Type and Number:
Japanese Patent JP3164397
Kind Code:
B2
Abstract:
PURPOSE: To converge a light spot small without lowering the utilization efficiency of light and generating a side-rope in an optical head converging a laser beam irradiating a disk surface.
CONSTITUTION: The laser beam 1 transmitting a phase board 6 having prescribed refractive index is converged by a lens 3 and irradiates the surface of the disk 4. The laser beam 1 transmitting areas 7a and 8a of the phases board 6 is made incident on the lens 3. Also, the phase of the laser beam 1 transmitting second areas 7 and 8 provided projectingly from the first areas 7a and 8a is changed by odd times as long as half-wavelength of the laser beam to the phase of the laser beam transmitting the first areas 7a and 8a and the laser beam is made incident on the lens 3. The first areas and the second areas 7, 7a, 8 and 8a are formed concentrically about an optical axis 5 and alternately.
Inventors:
Nagaaki Koshino
Masami Tsutsumi
Masami Tsutsumi
Application Number:
JP4971992A
Publication Date:
May 08, 2001
Filing Date:
March 06, 1992
Export Citation:
Assignee:
富士通株式会社
International Classes:
G02B27/09; G02B27/00; G02B27/52; G11B7/135; (IPC1-7): G02B27/52; G11B7/135
Domestic Patent References:
| JP5196896A | ||||
| JP4123016A | ||||
| JP3283024A | ||||
| JP63228426A | ||||
| JP61195534U |
Attorney, Agent or Firm:
Tadahiko Ito (2 outside)