Problems and Approaches for Remote Fiber Optic Absolute Sensors

Abstract

Cost, accuracy and reliability requirements dictate the need to critically examine the fiber optic sensor approaches that are currently being pursued for making absolute measurements. Typical absolute measurements require only moderate sensitivity but high static accuracy over wide environmental conditions. In many applications, in situ calibration is not possible, yet high accuracy must be maintained with tens or hundreds of meters of fiber optic cable and multiple connectors separating the optical sensor head from the associated electronics. For many fiber optic sensor approaches, uncontrollable cable and connector loss variations limit achievable accuracy to a few percent. We present experimental data on cable and connector loss variations and review the resulting accuracy limitations for a variety of generic sensor approaches.