FIBER OPTIC SENSOR AND METHOD FOR DETECTING SHOCK WAVE PRESSURE AND MASS VELOCITY IN SOLID MEDIA

摘要

A fiber optic pressure and mass velocity sensor for measuring a shock wave pressure in a solid media includes an optical fiber having a means for measuring a change in an optical path length (OPL) of the fiber when positioned in the solid media caused by the shock wave altering the physical length of the fiber and the refractive index of the fiber. The means for measuring the change in the OPL is coupled at one end to a laser and at its second end to a means for detecting the change in OPL. The sensor has a high operating bandwidth (>>10 MHz), is sufficiently rigid to withstand the force of the shock wave, has a sensitivity that can also be tailored for the application, and is immune to electromagnetic interference. Measurement can be made on materials under extreme strain conditions, and the sensor can also provide characterization of protective materials such as bullet/blast proof materials.

主权项

1. A differential displacement sensor for measuring a shock wave mass velocity in a solid media, comprising
a Michelson interferometer (MI) having an input and an output, comprising: a first interferometric arm comprising a cleaved first optical fiber with a first end face having a first mirror surface coating thereon, a second arm comprising a cleaved second optical fiber, an acousto-optic modulator, and a second end face having a second mirror surface coating thereon, a coherent laser coupled to the MI input, and a detector coupled to the MI output, and wherein the first and second optical fibers are aligned parallel to each other and the first and second endfaces are spaced-apart axially a distance sufficient so as to register a measurable phase shift due to a differential displacement of the first and second endfaces corresponding to a rate of change of a mass displacement due to a travelling shock wave in the solid media equal to the mass velocity.