Advanced Photoacoustic Imaging Using Full Matrix Capture Data Acquisition

Full Matrix Capture (FMC), when used with the Total Focusing Method (TFM), may offer an improvement on the Synthetic Aperture Focusing Technique (SAFT) algorithm. FMC is a data acquisition process which captures A-scan (time-amplitude) data for every transmitterreceiver combination of elements in an array. The technique uses a ?transmit on one and receive on all? data capture approach. This work reports on an experimental laser ultrasound setup capable of synthesising an ultrasonic array and thus being able to collect the data needed to perform FMC. An aluminium block with several side drilled holes at 15 mm depth from the top surface has been inspected using laser based SAFT and FMC techniques. The B-scan reconstructions clearly show the response from the side drilled holes in an easy to interpret form. It was found that the maximum improvement in indication signal to noise ratio (SNR) using the FMC & TFM technique was 2.9 dB when compared to SAFT.