|Publication Number||US 8649638|
A method for measuring the deformation of a specimen using an extensometer having a loop of a single-mode optical fiber. At least two points of the loop are attached to desired locations on a specimen. Light is transmitted through the loop and the transmitted optical power is measured by a photodetector. The deformation of the specimen causes the size and shape of the loop to change, which changes the transmitted optical power. The change in optical power is related to extension or compression using calibration curves. The sensor works on the principle of transmitted power modulation through the curved section.
- 1. A method for measuring the deformation of a specimen comprising the steps of: a) attaching a fiber-optic extensometer to a specimen of interest, wherein the fiber-optic extensometer comprises i) a loop of a single-mode optical fiber; ii) a light source attached to a first end of the loop for transmitting light having an optical power through the loop; and iii) a photodetector attached to a second end of the loop for detecting the light transmitted through the loop, b) transmitting the light supplied by the light source through the loop; c) deforming the specimen while the light is being transmitted through the loop, wherein deformation of the loop changes the optical power of the light being transmitted through the loop; d) using the photodetector to detect any change in optical power of the light passing through the loop; and e) coupling the photodetector to a computer having a database of the calibration curves relating the change in the optical power to the deformation of the loop, wherein the change in the optical power of the light being transmitted through the loop is related to the deformation of the loop using calibration curves.
- 2. The method as claimed in claim 1, wherein the loop is attached to the specimen at least two points.
- 3. The method as claimed in claim 2, wherein the two points are diametrically opposite each other.
- 4. The method as claimed in claim 1, wherein the extensometer is bonded to a surface of the specimen.
- 5. The method as claimed in claim 1, wherein the extensometer is embedded inside the specimen.
- 6. The method as claimed in claim 1, wherein the extensometer is used in a large measurement range with a lower measurement sensitivity and in a small measurement range of one intermediate peak at high sensitivity.