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:
Jul. 23, 2013
Filed:
Aug. 04, 2009
Joseph D. Tobiason, Woodinville, WA (US);
Toru Yaku, Kawasaki, JP;
Emi Kaneko, Yokohama, JP;
Eric H. Altendorf, Everett, WA (US);
Joseph D. Tobiason, Woodinville, WA (US);
Toru Yaku, Kawasaki, JP;
Emi Kaneko, Yokohama, JP;
Eric H. Altendorf, Everett, WA (US);
Mitutoyo Corporation, Kawasaki-shi, JP;
Abstract
A method and apparatus for suppressing loss of scale image contrast due to interference effects from optical path length differences, including lens profile aberrations, are provided in a displacement sensing optical encoder that uses a telecentric imaging configuration. According to the invention, the encoder is configured such that the image light that reaches the detector comprises symmetric ray bundles concentrated symmetrically on opposite sides of the optical axis center at the limiting aperture of the telecentric imaging configuration. Central ray bundles, and/or other ray bundles that have an optical path lengths significantly different than the operational symmetric ray bundles are prevented or blocked. As a result destructive interference is prevented and image contrast is improved.