Scanning laser interferometric evaluation of individual elements and an entire micro-electro-mechanical ultrasonic array transducer

A high resolution scanning laser interferometer was used to map the dynamic displacements of individual elements, as well as the entire array of a micro-electro-mechanical ultrasonic transducer. Peak displacement levels were measured as a function of frequency, DC bias voltage, and AC drive voltage. An analysis of the displacement field for individual transducers showed evidence of over-responsive, under-responsive and non-responsive elements. The experimental results were compared with theoretical calculations for a circular membrane model, and were in reasonably good agreement. The role and influence of sidewall supports on the membrane motions is also discussed.