Radiant energy – Photocells; circuits and apparatus – Photocell controls its own optical systems
Reexamination Certificate
2004-12-17
2009-08-04
Epps, Georgia Y (Department: 2878)
Radiant energy
Photocells; circuits and apparatus
Photocell controls its own optical systems
C250S23700G, C369S044210, C369S112030, C359S833000
Reexamination Certificate
active
07569801
ABSTRACT:
An optical head, capable of performing output control for a light source without weakening an intensity of a light beam for recording and reproduction even if an optical element is not added anew, and an optical recording and reproducing apparatus including the optical head. Light fluxes near the center of an optical beam emitted from a light source are made incident on a diffractive element and transmitted through a beam splitter or the like to be irradiated on an optical recording medium. On the other hand, a part of peripheral light fluxes of the light beam are reflected in a direction substantially perpendicular to an optical axis by a reflection surface of a holder provided at an end of the diffractive element. Light beams reflected on the reflection surface are made incident on a photo-detector, and the photo-detector converts the light beams into an electric signal for output monitor of the light source according to an amount of received light. This electric signal for output monitor is fed back to a drive circuit of the light source to thereby perform control for an output of the light source.
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Japanese Abstract of Japan; Publication No. 2002-270940 Published on Sep. 20, 2002; Application No. 2001-066445 filed Mar. 9, 2001; Applicant: Hitachi Koki Co., Ltd., Inventor: Kataoka Keiji.. *abstract*.
Edwards Angell Palmer & & Dodge LLP
Epps Georgia Y
TDK Corporation
Williams Don
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