LOW-DRIFT FIBER OPTIC SONAR DOME PRESSURE TRANSDUCER

THE DEVELOPMENT OF A HIGHLY RELIABLE, LOW DRIFT, FIBER OPTIC HYDROSTATIC PRESSURE SENSOR FOR SONAR DOMES IS PROPOSED. THE SENSOR IS BASED ON THE ELASTO-OPTIC EFFECT IN OPTICAL CRYSTALS. THE SENSING ELEMENT IS AN OPTICAL CRYSTAL, AND BECAUSE NO MOVING PARTS ARE INVOLVED, WEAR AND FATIGUE ARE REDUCED TO A MINIMUM. BECAUSE OF ITS INHERENT LINEARITY AND LOW DRIFT, THE PROPOSED PRESSURE SENSOR WILL BE IDEAL FOR MONITORING PRESSURE IN SHIPBOARD SONAR DOMES. PRESSURE ALTERS THE BIREFRINGENCE PROPERTIES OF CRYSTALS AND CHANGES THE STATE OF POLARIZATION OF LIGHT PASSING THROUGH THE CRYSTAL. THE GOAL OF THE PHASE I RESEARCH AND DEVELOPMENT EFFORT IS TO DEMONSTRATE THE FEASIBILITY OF THIS PRESSURE SENSING TECHNIQUE. SUITABLE OPTICAL MATERIALS WILL BE IDENTIFIED THROUGH A LITERATURE SURVEY. THE HIGHEST RANKED CRYSTAL MATERIALS WILL BE TESTED UNDER HYDROSTATIC PRESSURES. A TEMPERATURE COMPENSATION METHOD USING A SECOND ELASTOOPTIC CRYSTAL IS PROPOSED. MATERIALS FOR THE TEMPERATURE COMPENSATION CRYSTAL WILL BE IDENTIFIED AND THE TEMPERATURE INDEPENDENCE OF THE PRESSURE READING WILL BE EXPERIMENTALLY VERIFIED.