The design, phase stability and strain sensitivity of a fiber optic interferometric strain sensor are discussed. For this sensor, the laser diode is modulated with a pulsed 100 MHz RF signal. The phase difference between the modulation recovered from the sensing leg and the reference RF oscillation is proportional to strain. Strain sensitivities as low as + 4.5 x 10-4 were measured.
E. O. Rausch,
P. B. Ruffin,
"Fiber Optic Strain Sensing With Rf Interferometric Techniques", Proc. SPIE 1170, Fiber Optic Smart Structures and Skins II, (5 February 1990); doi: 10.1117/12.963119; https://doi.org/10.1117/12.963119