Abstract: Exemplary practice of the present invention provides an air vehicle and at least one interferometric double-path fiber optic sensor connected with the air vehicle. Each fiber optic sensor includes a pair of optical fibers, viz., an optical sensing fiber and an optical reference fiber, in a parallel and propinquus relationship. The paired optical fibers of each fiber optic sensor are attached to the air vehicle either (i) circumferentially around the fuselage or (ii) lengthwise along the fuselage or (iii) span-wise along the wings and across the fuselage, and are configured whereby the sensing fiber is exposed to the atmosphere and the reference fiber is not. Each fiber optic sensor senses atmospheric infrasound but does not sense atmospheric wind noise, which is negated by incoherency associated with design lengthiness of the optical fiber pair. Noise and strain due to temperature, vibration, and propulsion are neutralized via interferometric common mode rejection.

Abstract: Exemplary practice of the present invention provides an air vehicle and at least one interferometric double-path fiber optic sensor connected with the air vehicle. Each fiber optic sensor includes a pair of optical fibers, viz., an optical sensing fiber and an optical reference fiber, in a parallel and propinquus relationship. The paired optical fibers of each fiber optic sensor are attached to the air vehicle either (i) circumferentially around the fuselage or (ii) lengthwise along the fuselage or (iii) span-wise along the wings and across the fuselage, and are configured whereby the sensing fiber is exposed to the atmosphere and the reference fiber is not. Each fiber optic sensor senses atmospheric infrasound but does not sense atmospheric wind noise, which is negated by incoherency associated with design lengthiness of the optical fiber pair. Noise and strain due to temperature, vibration, and propulsion are neutralized via interferometric common mode rejection.