The patent badge is an abbreviated version of the USPTO patent document. The patent badge does contain a link to the full patent document.
The patent badge is an abbreviated version of the USPTO patent document. The patent badge covers the following: Patent number, Date patent was issued, Date patent was filed, Title of the patent, Applicant, Inventor, Assignee, Attorney firm, Primary examiner, Assistant examiner, CPCs, and Abstract. The patent badge does contain a link to the full patent document (in Adobe Acrobat format, aka pdf). To download or print any patent click here.
Patent No.:
Date of Patent:
Feb. 14, 1995
Filed:
Jul. 15, 1992
Joseph F Revelli, Jr, Rochester, NY (US);
Eastman Kodak Company, Rochester, NY (US);
Abstract
An integrated optic head contains a planar and a channel waveguide, a waveguide condensing lens, and integrated waveguide photodetectors. The main portion of the beam returning from the disk is focused by the lens onto an integrated waveguide photodetector to provide the data signal. A smaller portion of the beam is sampled by channel waveguide Mach-Zehnder (MZ) interferometers that measure the beam wavefront curvature to provide the focus error signal (FES). Additional channel waveguides provide reference signals for the interferometers and provide a means of measuring the tracking error signal (TES). The TES method includes subtracting light detected by one channel waveguide detector from light detected by another, which difference is the tracking error. The FES method includes obtaining the difference in the ratios of the light emanating from two interferometers divided by the light emanating from their respective channel waveguides, which difference in ratios is the focus error.