Fiber optic sound and strain measurements employing newly developed digital demodulators

Abstract

Fiber optic interferometric sensor systems for “smart” materials and structures applications offer a number of advantages including minimal electrical interference, geometric flexibility, and multisensor capability. Demodulation of these interferometric sensor signals typically is carried out by analog hardware. However, accuracy, bandwidth, and linearity are hampered by limitations in available electronic components and low-performance analog filters. A high-precision off-line digital demodulator has been developed and the techniques with fiber optic strain gauges and hydrophones are demonstrated. The measurement system is unique and represents an advancement in the state-of-the-art. A real-time implementation for control applications based on the Texas Instruments Inc. TMS 320C25 signal processing chip set is also proposed.