Development of a High Frequency Microphone Array for Beamforming of Air-Ultrasonic Signals in Nondestructive Testing
* Presenting author
Ultrasonic nondestructive testing methods are well established to inspect components for detection of flaws and discontinuities. Though, linear and phased array signal processing techniques have been widely used, less research has been conducted on contactless nondestructive testing with passive arrays. In this study we present preliminary investigations with beamforming techniques for air ultrasonic signal localization. We use a virtual microphone array with 32 elements and 20 cm diameter. An ultrasonic trans-ducer with 75 kHz center frequency was placed behind a screen with a small hole to send the signals, and the position of the hole was localized by the microphone array. We investigated the resolution of the array by measuring the beam width at different distances between source and array in the range of 10 cm up to 20 cm. Furthermore the reconstruction results were compared with beamforming simulations in order to test the functionality of the ultrasonic array.