High-Temperature Optical Fiber Sensors for Adverse Environments

The materials and technology now exist to construct a miniaturized fiber optic microphone utilizing on-line calibration techniques for high-temperature, high acoustic amplitude wind tunnel instrumentation. Sapphire optical fibers, with melting temperatures above 2260 k (1980 C, 3600 F) have recently been fabricated with optical losses low enough to begin constructing fiber optic sensors with high operating temperature capability. Fiber and Sensor Technologies (F&S) has demonstrated a sapphire displacement sensor up to 2020 K (1750 C, 3180 F), for measurement of strain and temperature. The Fiber & Electro-Optics Research Center (FEORC) at Virginia Tech and researchers at NASA Langley has demonstrated a cooled silica fiber optic microphone for use in hostile environments at temperatures up to 1370 K (1090 C, 2000 F) at 160 dBA, NASA patent disclosure LAR 14640-1. The research team has also demonstrated a novel dynamic calibration technique using fluidic technology, as well as a fiber optic interface for use with fluidic devices. The results of these demonstrations form the basis of two separate patent disclosures. Fiber and Sensor Technologies has licensed an enabling patent titled "Sapphire Optical Fiber Sensors" and will build upon this demonstrated technology i the proposed Phase I SBIR program to construct miniaturized microphones with on-line calibration capabilities.