RESUMO
An all optical-fiber-based approach to measuring high explosive detonation front position and velocity is described. By measuring total light return using an incoherent light source reflected from a linearly chirped fiber Bragg grating sensor in contact with the explosive, dynamic mapping of the detonation front position and velocity versus time is obtained. We demonstrate two calibration procedures and provide several examples of detonation front measurements: PBX 9502 cylindrical rate stick, radial detonation front in PBX 9501, and PBX 9501 detonation along curved meridian line. In the cylindrical rate stick measurement, excellent agreement with complementary diagnostics (electrical pins and streak camera imaging) is achieved, demonstrating accuracy in the detonation front velocity to below the 0.3% level when compared to the results from the pin data. Finally, an estimate on the linear spatial and temporal resolution of the system shows that sub-mm and sub-µs levels are attainable with proper consideration of the recording speed, detection sensitivity, spectrum, and chirp properties of the grating.
RESUMO
A reflectively monitored optical-fiber Fabry-Perot interferometer was embedded in a graphite-epoxy composite material. Its performance as a temperature sensor was demonstrated from 20 to 200 degrees C. The change in relative phase shift with temperature, Deltaø/øDeltaT, was measured to be 8.0 x 10(-6)/ degrees C for this embedded sensor. This value is 4% lower than for one employing a similar fiber in an air ambient. A thermal expansion coefficient for the composite material in the direction of the fiber axis is estimated from these data to be 2.1 x 10(-7)/ degrees C.
RESUMO
A fiber-optic gyro is described that employs closed-loop phase compensation. Preliminary experimental results are reported of the sensing of rotation rates down to 0.5 degrees /sec for a 135-mm-radius, 100-m-length fiber coil.
