Embedded Fiber Optic Sensors (EFOS)

Current laser interferometry pressure pulse detection techniques use the shock-induced change in index of refraction to track detonation and/or shock fronts in a single fiber optic by reflecting laser light off the boundary created between the unshocked material and the shocked material. This technique cannot be used in regimes where there isn't a strong enough shock front to reflect the laser light above the noise floor. Other embedded fiber techniques use a chirped fiber Bragg grating to track a shock position versus time by correlating a known spectrum of light to a calibrated position. These two systems use a single fiber and measure only time-of-arrival for a strong shock.