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. 21, 2011
Filed:
Nov. 20, 2008
Avron Zwilling, Redmond, WA (US);
Joseph Daniel Tobiason, Woodinville, WA (US);
Scott Harsila, Bothell, WA (US);
Karl Gustav Masreliez, Banyuls-sur-mer, FR;
Avron Zwilling, Redmond, WA (US);
Joseph Daniel Tobiason, Woodinville, WA (US);
Scott Harsila, Bothell, WA (US);
Karl Gustav Masreliez, Banyuls-sur-mer, FR;
Mitutoyo Corporation, Kawasaki-shi, JP;
Abstract
A reference mark configuration for an interferometric miniature grating encoder readhead using fiber optic receiver channels is provided. The readhead includes primary fibers that provide reference mark primary signals processed to generate a reference signal with accuracy of approximately 0.2 microns. The readhead may include secondary fibers used to generate reference mark secondary signals processed to generate a reference signal with accuracy of approximately 20 nanometers. Spatial filter masks configured for the secondary fiber optic receiver channels provide two spatially periodic secondary signals arising from interference fringes outside of the receiving area of the primary fiber optic receiver channels. The secondary signals are out of phase with one another and their spatial frequency is higher than that of the primary signals. A signal crossing of the reference mark secondary signals is identified that is spatially adjacent to a signal crossing of the reference mark primary reference signals.