Validation of the absolute extrinsic Fabry-Perot interferometer for strain measurements

Abstract

This report presents the results of experiments performed to verify the performance of the fiber-optic absolute extrinsic Fabry-Perot interferometer (AEFPI) for strain measurements. In these experiments, AEFPI sensors are surface mounted and embedded in various materials and subjected to mechanical and thermal strains. Strains measured by the AEFPI are compared to analytical predictions and to metallic foil strain gage measurements where possible. The AEFPI sensors and demodulation equipment were purchased from Fiber and Sensor Technologies (F&S) in Virginia, and all experiments were performed at the Composites Laboratory of Sandia National Laboratories in Livermore, California. The results of the tests indicate that these sensors are suitable for static and quasi-static strain measurements in both surface mounted and embedded configurations; however, they have a resolution of 100 (mu) (epsilon) , which limits their potential applications. A brief explanation of the theory behind the operation of the AEFPI sensor is presented along with the manufacturer's specifications for the particular model used in thee experiments. The details of the experiments are then described, and a summary of the results presented. Finally, conclusions regarding the accuracy, resolution, linearity, and repeatability of the AEFPI are extracted from the data.