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:
Mar. 31, 1992
Filed:
Jul. 25, 1990
Daniel R Marshall, Boise, ID (US);
Hewlett-Packard Company, Palo Alto, CA (US);
Abstract
A method and apparatus for producing position error signals from a beam of light, called an input light beam, reflected from an optical surface of recording media, employs a detector prism which has a steep angle, reflection/transmission interface. A prism, such as a dove prism, separate from the detector prism, or other optical structure, integral with the detector prism, having one or more Brewster angle faces on which the input light beam is incident, is employed for inverting a portion of equal portions of the input light beam prior to incidence of the resulting beam on the reflection/transmission interface of the detector prism. Crossing of the marginal rays in the transmitted and reflected complementary light beams now does not invert the slope of the error signal. Now the error signal is not bilaterally sensitive in the respective complementary light beams. The signal instead is now generated by the difference in the total light energy in the respective transmitted and reflected complementary light beams.