A transmit reflect detection system for fibre bragg grating acoustic emission and transmission sensors
Computing, Health and Science
Engineering, Centre for Communications Engineering Research
A Transmit Reflect Detection System (TRDS) for a Fibre Bragg Grating (FBG) acoustic emissions and transmissions sensor is demonstrated. The TRDS utilises both the transmitted and reflected signals from the FBG. A narrow line width laser source is tuned to one of the 3 dB points of the FBG. The transmitted and reflected signals are detected, via two photoreceivers. The difference between the transmitted and reflected signals is then taken, doubling the total received signal. The TRDS improves the sensitivity and efficiency of the FBG acoustic emission and transmission sensor. The TRDS and FBG sensor was used to successfully receive actively generated ultrasonic signals, including acoustic communications signals, and to detect acoustic emissions. We include results for the sensitivity, frequency response, and transient response of the FBG sensor, and the acoustic emissions for low velocity impacts, and a lead pencil break test.