Integrated Piezoelectric Ultrasonic Receivers for Laser Ultrasound in Non-destructive Testing of Metals

Thick (>50 μm) piezoelectric films have been deposited directly on top of steel and aluminum substrates as integrated ultrasonic transducer (IUT) receivers to detect laser generated ultrasound. The film fabrication is based on a sol-gel spray technique. In this study IUTs intrinsically acting as bulk longitudinal wave receivers use various mode conversion approaches and serve as longitudinal, shear, symmetric, anti-symmetric and shear horizontal plate wave receivers. Different laser generation conditions such as point and line sources of different sizes are also applied to investigate the capabilities of IUT receivers. Ultrasonic measurements on metal substrates with planar and curved surfaces at temperature up to 400°C using laser generated and IUT ultrasound receiver are demonstrated.