COMPENSATION TECHNIQUES FOR AMPLITUDE MODULATED FIBER OPTIC SENSOR SYSTEM

A MAJOR DEFICIENCY OF AMPLITUDE MODULATED (AM) FIBER OPTIC SENSORS IS THE LIMITED ACCURACY DUE TO THE ENVIRONMENTALLY INDUCED LOSS VARIATIONS OF THE FIBER-OPTIC TRANSMISSION LINK. THE DUAL WAVELENGTH TECHNIQUE HAS SHOWN TO BE INADEQUATE SINCE THE LOSS VARIATIONS ARE WAVELENGTH DEPENDENT. THE OBJECTIVE OF THE PROGRAM IS TO EXPERIMENTALLY CHARACTERIZE THE LOSS VARIATIONS OF THE FIBER OPTIC CABLES AND CONNECTORS AND TO DEVELOP AN EFFECTIVE COMPENSATION TECHNIQUE. TO ACHIEVE THIS GOAL IT IS PROPOSED TO USE A UNIQUE DEVICE, THE ACOUSTO-OPTIC TUNABLE FILTER (AOTF), BOTH AS A TOOL IN THE EXPERIMENTAL INVESTIGATION AS WELL AS A MEANS TO COMPENSATE THE UNCONTROLLED TEMPERATURE EFFECT ON THE LOSS VARIATIONS. IN ADDITION TO PROVIDING THE DESIRED COMPENSATION FOR CABLE AND CONNECTOR LOSS, THE USE OF THE AOTF OFFERS THE FOLLOWING ADVANTAGES: INCREASING SENSOR ACCURACY, STABILITY AND SENSITIVITY, POTENTIAL FOR MULTIPLEXING SENSORS AND COMPACT, RUGGED CONSTRUCTION COMPATIBLE TO MILITARY ENVIRONMENTS.