Ultrasonic air-coupled metrology of material surfaces

This paper describes a new design of air-coupled transducers based on a 1-3 piezocomposite that can be shaped with different focal geometries. Flat and focused transducers up to 4 MHz have been developed and characterized. Surface information of soft and hard materials has been obtained showing the big potential of air-coupled ultrasound to perform profilometry of material surfaces where traditional optical and contact methods are inadequate.