Validation of a 3D ultrasound microscopy system designed for the detectionof air bubble inclusions in thermal spray polymer

Thermal spray processing produces coatings containing a large amount of por osity (air bubbles). The mechanical properties of the coatings are governed by the inclusion rate and size. In this paper we propose a 3D ultrasound m icroscopy system to detect and locate these inclusions. The sample is XY sc anned in 50 mum steps by a 44.6 MHz ultrasound pulse echo system. Each RF l ine is processed by a modified split spectrum processing algorithm. Results can be displayed as 2D or 3D images. To validate the system, the detected inclusions are compared with the optical microscope view of a transparent p olymer phantom. The ultrasonic representations yield topologic information which cannot be obtained from the optical picture.