Optical fiber sensors can be designed to measure the concentration or presence of various chemical species in liquid or vapor form. When used in rugged or explosive environments, fiber optic sensors provide several advantages over conventional electrical based sensors, including: small size, light weight, corrosion resistance, geometrical flexibility and an inherent immunity to electromagnetic interference (EMI).



The general principle behind fiber optic sensors is relatively simple. When optical fibers are used in telecommunications (phone lines), it is undesirable to have the carrier light pulses affected by either mechanical or environmental factors.

An obvious example would be if a fiber was cut resulting in a total loss of carrier light. However subtle environmental factors affect both fiber and fiber components. By isolating and comparing the effect of light in a fiber exposed to a known environmental factor, one can detect or quantify that factor.