Enabling multi-input, multi-output measurements with a fluidic transducer

Abstract

Ultrasonic testing is a widely used method for detecting damage and material characteristics in fields ranging from medicine to aerospace applications. The use of air-coupled ultrasound (ACU) enables an increase in testing speed, since no coupling medium needs to be applied to the transducer-specimen interface at each measurement point. The time needed for testing can be further decreased by using multiple-input, multiple output (MIMO) measurement systems. These systems require the ultrasonic signals to be uncorrelated so the that the individual pulses can be discriminated. Recently, the fluidic transducer was introduced, which generates acoustic pulses in the low ultrasonic frequency range. Experimentally, it is shown that each pulse contains a unique phase signature, that can be extracted by removing the signal envelope information. This technique is used to uniquely discriminate between simultaneously triggered pulses from two fluidic transducers and measure their individual times of flight.