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. 29, 1994
Filed:
Mar. 31, 1992
Bruce N Nelson, South Boston, MA (US);
Malcolm C Smith, Holliston, MA (US);
Geo-Center, Inc., Newton Centre, MA (US);
Abstract
A stress sensor having directional measurement capabilities based on the photoelastic effect in isotropic photoelastic materials. Directional measurement capability is achieved in the sensor by the incorporation of three different optical axes passing through the photoelastic element. This creates three independent stress sensors which utilize a single sensing element. Each of the three independent stress sensors are sensitive to applied stress in different directions. The response of each of the sensors is analyzed and the magnitude and direction of incoming stress is determined. The use of a sum-difference output detection scheme results in immunity to light source intensity variations, optical fiber microbending losses, and fiberoptic connector losses. The stress sensor is immune to electromagnetic interference (EMI) and electromagnetic pulse (EMP), and is compatible with fiberoptic data transmission and control lines.