OVERLOAD PROTECTION FOR FIBER OPTIC MICROBEND SENSOR

摘要

OVERLOAD PROTECTION FOR FIBER OPTIC MICROBEND SENSOR Jaws of a microbend sensor have corrugations and hold an optical fiber therebetween. One jaw is movable with respect to the other for squeezing and bending the optical fiber between the corrugations. The amount of bending modulates light passing through the fiber which can be a measurement of the relative movement between the jaws. The relative movement can be a mechanical input of a microbend sensor for sensing a process variable, for example a flow rate in a vortex shedding flowmeter. According to the invention, the corrugations of each jaw comprise flat areas lying in a common plane for each jaw extending perpendicularly to the displacement direction of the jaws, and projections extending parallel to the displacement direction of the jaws and positioned between the flat areas. The projections of each jaw are positioned to face the flat areas of the other jaw with the optical fiber being held between the projections. Upon receiving an overload which tends to press the jaws together, the projections of one jaw press bends of the optical fiber against flat areas of the other jaw.