Patent ID: 7068869

Claim:
A fiber Bragg grating strain gage for measuring strain in a structural element comprising: a frame having a first end and a second end wherein said first end of said frame includes means for adjustably engaging a pointer and said second end of said frame includes means for engaging an optical fiber and wherein the distance between said means for adjustably engaging a pointer and said means for engaging an optical fiber has a predetermined value L 1 , a pointer having a first end and a second end wherein said first end of said pointer is adjustably engaged with said first end of said frame and said second end of said pointer includes means for engaging an optical fiber and wherein the distance between said second end of said pointer and said first end of said frame is set to a value of L 2 , and wherein the coefficient of thermal expansion of said pointer is α, an optical fiber containing a fiber Bragg grating having a first attachment point and a second attachment point wherein said first attachment point is engaged with said second end of said pointer and said second attachment point is engaged at said second end of said frame, and wherein β T is the temperature sensitivity of said fiber Bragg grating and β ε is the strain sensitivity of said fiber Bragg grating, means for fixing said frame to a structural element.