Fiber optic sensors with optical common mode rejection

A technique of optical common mode rejection (OCMR) is described for use with fiber optic sensors that employ strain induced birefringence as a transducer mechanism. The technique is applicable to both multimode fiber optic sensors based on photoelastic effect and single mode polarimetric sensors. The use of OCMR permits the development of differential fiber optic sensors that are insensitive to changes in environmental ambients. A flowmeter concept based on the technique is analyzed via Mueller Calculus and optimum device performance predicted.