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. 25, 1986
Filed:
Jan. 24, 1985
Gunter Makosch, Sindelfingen, DE;
International Business Machines Corporation, Armonk, NY (US);
Abstract
A method and apparatus is described for making absolute and relative distance measurements optically. A grating, or gratings, is located on the object whose displacement is to be measured, or on a surface in contact with the object. Two perpendicularly polarized light beams interact with the grating to produce a phase difference therebetween. This phase difference is a measure of the displacement of the object, and can be compensated for in order to determine the exact displacement of the object. The relative displacement between two objects can be measured in a similar way, there being gratings on the two objects. One of the light beams strikes one grating while the other strikes the second grating. If there is perfect alignment between the gratings on the two objects, there will be no phase difference in the diffracted light from the gratings. If there is misalignment between the objects, a phase difference between the diffracted signals will be produced indicative of this misalignment.