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:
Oct. 31, 1995
Filed:
Jun. 30, 1994
Lloyd C Bobb, Horsham, PA (US);
Howard D Krumboltz, Chalfont, PA (US);
The United States of America as represented by the Secretary of the Navy, Washington, DC (US);
Abstract
An optical fiber strain sensor is provided which remembers the maximum stn a structure has experienced in a given timeframe. A reflective surface is fixed at one location on the structure, and a multi-mode optical fiber with a flat end is fixed at another location on the structure and is positioned so that its flat end is in contact with the reflective surface. A microbore capillary tube attached to the reflective surface encloses the fiber at its flat end and frictionally retains it in contact with the reflective surface. Increasing strain in the structure pulls the fiber end away from the reflective surface in proportion to the amount of strain; however, when strain is decreasing, the fiber buckles rather than moving closer to the reflective surface. Therefore, the maximum strain is reflected as a maximum distance between the fiber end and the reflective surface. When the maximum strain experienced is to be measured, light is launched into the free end of the fiber and reflected back through the fiber by the reflective surface. Its intensity is then detected and measured. The intensity of light transmitted to the detector will vary inversely with the distance between the fiber end and the reflective surface; therefore, this distance can be measured and correlated with strain to a high degree of accuracy.