A 2D static ultrasonic array of passive probes for improved probability of detection

An experiment was conducted to investigate the potential of using the passive (awaiting active pulsing) transducers in a 2D ultrasonic array as signal receivers. This paper will demonstrate that this new technique normal probe diffraction (NPD) which can increase the probability of detection (POD), without increasing the amount of false positives. Three 10 mm diameter, 5 MHz straight beam probes were used at linear distances of 22.5 and 45 mm, from the transmitter. A V1 calibration block was used as an aid to experimental repeatability, and the 2 mm notch was utilized as a pseudo defect. The probes were used in a single transmission (Tx) with dual receiver (Rx) formation in alternate positions, to collect information from areas of the sound field that would be lost using a standard pulse echo technique. The readings were taken from the area prior to the first backwall echo because this eliminates confusion due to the sidewall reflections. The experiments will show that the diffracted echo signal can be detected using the passive probes using NPD techniques.