HIGH PRESSURE FIBER OPTIC SENSOR FOR NUCLEAR TEST INSTRUMENTATION

THE GOAL OF THIS PHASE I EXPERIMENTAL EFFORT IS TO DEMONSTRATE THE FEASIBILITY OF USING AN OPTICAL GLASS AS A SENSING ELEMENT FOR VERY HIGH PRESSURE MEASUREMENTS. CURRENTLY, PIEZO-ELECTRIC GAUGES ARE TYPICALLY USED. AS THESE SENSORS ARE ELECTRICAL IN NATURE, THEY ARE ADVERSELY AFFECTED BY ELECTROMAGNETIC INTERFERENCE (EMI) WHICH IS CREATED IN A NUCLEAR EVENT. THE PROPOSED FIBER OPTIC SENSOR BASED UPON THE PHOTOELASTIC EFFECT IS INHERENTLY IMMUNE TO EMI. IN ADDITION, SUM-DIFFERENCE OUTPUT DETECTION METHODS WILL RESULT IN A FIBER OPTIC SENSOR WHICH IS LESS SENSITIVE THAN A SINGLE OUTPUT SENSOR TO THE EFFECTS OF NUCLEAR RADIATION (FIBER DARKENING), AS THE MONITORING OF BOTH OUTPUT POLARIZATIONS ALLOWS FOR THE SENSOR OUTPUT TO BE TRANSMITTED INTENSITY INVARIANT. BY INCORPORATING AN OPTICAL GLASS AS THE PHOTOELASTIC SENSING ELEMENT, A FIBER OPTIC SENSOR WITH A LINEAR SENSING RANGE OF APPROXIMATELY 12 KBAR AND AN AC BANDWIDTH CAPABILITY APPROACHING 1 MHZ CAN BE REALIZED.