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Additive manufacturing (AM) has been revolutionizing the manufacturing industry due to its ability to significantly reduce waste and produce components with intricate shapes. Laser Ultrasonics (LU) is a non-contact and couplant free method to generate and detect ultrasound. LU can accommodate complex component shapes; thus, it has the potential to provide a reliable in-process inspection method for AM components. In recent years the development of Laser Induced Phased Arrays (LIPAs) helped overcome the inherently low signal amplitudes of LU at the non-destructive, thermoelastic regime. In this paper, the Full Matrix Capture data acquisition method is used and a LIPA of 68 elements is synthesized in post processing. The Total Focusing Method imaging algorithm is applied for ultrasonic imaging. The technique is demonstrated on a highly scattering titanium alloy Wire Arc Additive Manufactured (WAAM) component producing high quality ultrasonic images, accurately imaging defects at depths up to 10mm below the inspection surface.

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A laser induced phased array (LIPA) synthesizes an ultrasonic array, performing beamforming in post processing and using lasers for ultrasonic generation and detection. It is a non-contact technique, with a small footprint and no need for couplant, offering remote ultrasonic imaging. In a previous work, the Full Matrix Capture (FMC) and the Total Focusing Method (TFM) have been adapted to LIPAs, providing superior imaging quality, overcoming the poor signal-to-noise ratio of conventional laser ultrasonics. However, long scanning times compromise industrial applications. Our aim is to optimise FMC for LIPAs, to achieve faster data acquisition, while ensuring that ultrasonic imaging is not undermined. In the work presented, optimisation of the data acquisition and signal processing is achieved by considering the directivity and sensitivity patterns of laser ultrasound. The array characteristics, such as the number of elements, pitch and distribution were optimised according to the location of defects, receiving input through post-processing performed performed in parallel. The potential of this method is demonstrated using previously experimentally acquired data. These simulated results are compared to the scanning times and image quality of conventional FMC. Results confirm that scanning time can be significantly reduced, leading to almost 10 times faster data acquisition for LIPAs.