Patent ID: 6804008
Filing Date: 2004-10-12
Classification: G01D

Abstract:
A method for sensing a physical condition, the method comprising:(a) generating light; (b) passing a first portion of the light through a first optical path comprising a first optical fiber, the first optical fiber being characterized by a first optical path length which changes in response to the physical condition; (c) passing a second portion of the light through a second optical path comprising a second optical fiber, the second optical fiber being characterized by a second optical path length which changes in a controllable manner; (d) causing the first portion of the light which has passed through the first optical path to interfere with the second portion of the light which has passed through the second optical path; (e) changing the second optical path length within the second optical fiber until step (d) results in an interference fringe having a maximum; and (f) determining the physical condition in accordance with a value of the second optical path length corresponding to the maximum of the interference fringe; wherein step (e) comprises changing a physical length of the second optical fiber through stretching the second optical fiber; and wherein the second optical fiber is wrapped around a pulley and secured to an anchor and is stretched by use of the pulley and the anchor.