Patent ID: 7796844
Filing Date: 2010-09-14
Classification: G01D,G01K,G01L,G02B

Abstract:
1. A temperature-compensated fibre optic strain gauge for measuring strain of a host structure, the strain gauge comprising: a mount to be operatively attached to the host structure, the mount having a void separating a first section of the mount from a second section of the mount; a first fiber Bragg grating (FBG) recorded within a core of an optical fiber to measure strain and temperature, the first FBG being located transverse to the void and a first end portion of the first FBG is operatively attached to the first section of the mount and a second end portion of the first FBG is operatively attached to the second section of the mount, the end portions of the first FBG being pre-strained by an amount larger than a predetermined operational range of the first FBG; a second fiber Bragg grating (FBG) recorded within the core of the optical fiber to measure temperature, the temperature measurement of the second FBG being used to eliminate temperature as an influence on the strain measurement of the first FBG, a first end portion of the second FBG is operatively attached to the first FBG and a second end portion of the second FBG is operatively attached to the mount so that the second FBG is free from strain; and removable bridging portions adjacent to the void to connect the first section to the second section of the mount, the bridging portions being removed after the mount is operatively attached to the host structure; wherein a right-side failure proof feature is provided by detecting whether a reflection wavelength reverts to an original Bragg wavelength of the first FBG to indicate whether the first FBG has broken.