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:
Jun. 30, 1987
Filed:
Nov. 05, 1984
Applicant:
Inventors:
Assignee:
Sony Magnescale Incorporation, Tokyo, JP;
Attorney:
Primary Examiner:
Assistant Examiner:
Int. Cl.
CPC ...
G01B / ;
U.S. Cl.
CPC ...
356356 ; 2502 / ; 356363 ;
Abstract
Optical instrument for measuring displacement comprising a movable diffraction grating used as a scale, a semiconductor laser device, photodetectors, and means for making two light beams diffracted by the diffraction grating interfere with each other in which displacement of said diffraction grating is measured, based on variations of interference signals. The laser device has a suitable coherency for making selectively two necessary light beams with equal optical path lengths interfere with each other.