DEVELOPMENT OF A DUAL FUNCTION SENSOR SYSTEM FOR MEASURING PRESSURE AND TEMPERATURE AT THE TIP OF A SINGLE OPTICAL-FIBER

A dual function sensor system has been developed for measuring pressur e and temperature at the tip of a single optical fiber. The sensor con tains three parts: a filter band-edge shift temperature sensor, a shor t wavelength reflecting dichroic filter, and a diaphragm-based spectra l modulation pressure sensor. The sensor system uses a separate and di stinct LED for interrogating each sensor, three 100/140 mum step-index fused couplers for managing light, and separate paired photodiode ass emblies for analyzing the return light signal from each sensor. In ben ch tests, each sensor performed to specification and, importantly, the re was no crosstalk between sensors. This dual function sensor design has potential catheter applications where catheter size must be kept t o an absolute minimum.