The SmartSonic interrogator is an interferometric instrument able to detect at acoustic frequencies the small changes in the lengths of fibre between selected pairs of sensors on a fibre Bragg grating (FBG) array. The high bandwidth and low noise floor of this measurement is such that the addition of a remote SmartSonic interrogator turns a FBG array into a string of sensitive optical microphones.
Unlike conventional distributed acoustic sensing (DAS), where the signal is modulated by very low intensity Rayleigh back scattered light, the SmartSonic interrogator sets up a series of virtual fabry-perot cavities between selected FBGs and then tracks the minute changes to these cavity lengths using an interferometer and advanced data processing. In effect, a quasi-distributed acoustic sensing, or Q-DAS, monitoring system, is established. The unique optical and data processing architecture of a SmartSonic Q-DAS system has certain key advantages over alternative technologies:
SmartSonic is a collaborative development between Smart Fibres (UK) and Optics 11 (NL).