Non-Intrusive Internal Three Strain Sensor Based Optical Fiber Technology

This proposal describes a conceptual design and initial conceptual experiments of a remarkably straight-forward internal sensor that is capable of measuring three orthogonal strain components. The proposed sensor uses three cascaded in-line micro Fabry-Perot cavities that are individually addressed using coherence division multiplexing. The Fabry-Perot cavities are fabricated from three very different response to applied strain. These three different types of optical fibers can be used to fabricate a single microsensor. The response of each fiber leads to three independent equations from which the axial and two orthogonal transverse strain components can be calculated. The end product of this effort will be the complete electrical, mechanical and optical design of a single transducer element that is less than 1 mm in length and which is capable of uniquely determining axial and two independent transverse strain components.