Optical Fiber Strain-to-Failure Sensor
Patent, filed 23 Oct 1995, patented 17 Jun 1997
NAVAL AIR WARFARE CENTER AIRCRAFT DIV PATUXENT RIVER MD
Pagination or Media Count:
A sensor and method are disclosed for determining if a region, defined by two end points, in a structure has exceeded a predetermined amount of strain. The sensor has an optical waveguide which has two ends for receiving and emitting light and which is fixable at two locations thereon to respective ones of the end points to define a sensing region there between. The sensing region has a first portion with a first length and a first cross-sectional area, and a second portion with a second length and a second cross-sectional area which is smaller than the first cross-sectional area. The lengths and cross-sectional areas are sized so that the optical waveguide has a strain failure point equal to the predetermined amount of strain. The lengths and cross-sectional areas are approximately sized according to the formula R Alpha 1 AlphaBeta 1, wherein R the ratio of the amount of strain in the second portion which will cause the optical waveguide to fail to the predetermined amount of strain in the structure, Alpha the ratio of the length of the first portion to the length of the second portion, and Beta the ratio of the cross-sectional area of the first portion to the cross-sectional area of the second portion.
- Optical Detection and Detectors
- Fiber Optics and Integrated Optics