Optical acoustic sensor
AssigneeMcDonnell Douglas Corporation
InventorsRichard F. Cahill, Eric Udd
Life of this patent
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Abstract
A light source is operated near its threshhold and its output is split and sent in opposite direction about a fiber optic coil which is exposed to acoustic energy. The recombined light out of the coil is modulated at acoustic frequency. The modulated light can be fed back to the light source which responds to the modulation with large amplitude variations which are sent to a detector for conversion into an electrical signal representative of the acoustic energy. Alternatively, the light beam may be directed from the fiber coil to the detector directly. The sensors can include components for rejecting noise at frequencies not of interest and a plurality of similar sensors can be formed in an array to obtain directional information or increased sensitivity.
Claims31
A sensor for acoustic energy which includes:
- a light source which produces a light output;
- a first beamsplitter positioned to split said light output of said light source into first and second beams;
- fiber optic coil means having first and second opposite ends into which said first and second beams respectively are introduced, at least a portion of said fiber optic coil means being subjected to acoustic energy which nonreciprocally phase shifts said first and second beams, said first beamsplitter being positioned to recombine said first and second beams out of said second and first ends respectively into a third beam which is modulated by said acoustic energy;
- and
- means to detect modulation present in said third beam and produce therefrom an output representative of said acoustic energy.
Dependencies are inferred from the claim text.