FIBER DRIVERN ACOUSTIC CAVITY SENSORS

CALCULATIONS AND MEASUREMENTS ARE PRESENTED TO DEMONSTRATE THAT LEAKY, CLOSED-END RESONATORS AND PARTIALLY CLOSED, OPEN-END RESONATORS CAN BE USED TO MEASURE THE PROXIMITY OF THE RESONATORS TO A SURFACE. CONVERSELY, FOR A FIXED SENSORRESONATOR POSITION, THE RESONATOR CHARACTERISTICS CAN BE USED TO DEDUCE TEMPERATURE AND COMPOSITION OF THE FLUID IN THE CAVITY. RESULTS ARE PRESENTED THAT SHOW HOW AN ACOUSTIC CAVITY CAN BE USED AS A SENSITIVE, WIDE DYNAMIC RANGE, LINEAR DISPLACEMENT SENSOR. THE METHODS DESCRIBED COULD EASILY BE EXTENDED TO THE DESIGN OF A SENSOR THAT COULD OPERATE AT ELEVATED TEMPERATURES AND EVEN IN CORROSIVEOR RADIOACTIVE ENVIRONMENTS. A NEW COMPOUND RESONATOR APPROACH IS UNDER DEVELOPMENT THAT REDUCES THE PHYSICAL SIZE OF THE RESONATOR FOR ANY GIVEN LINEAR DYNAMIC RANGE AND INCREASES SENSITIVITY TO SMALL DISPLACEMENTS. ACOUSTIC CAVITIES CAN FUNCTION VERY WELL NEAR ROUGH AND/OR NONFLAT SURFACES. WHEN DRIVEN BY ACOUSTIC FIBERS, THESE CAVITIES CAN BE PLACED IN VERY HARSH ENVIRONMENTS, REMOTE FROM THE SYSTEM ELECTRONICS.