Spatially Encoded Ultrasonic Generation for Laser-Induced Phased Array Imaging

Spatial encoding, such as Hadamard multiplexing, reduces signal-independent noise by averaging multiple signals in parallel, thus improving the SNR. This study presents the implementation of a multi-element Laser Induced Phased Array (LIPA), synthesised by projecting orthogonally encoded binary laser patterns onto an aluminium block containing nine, 1 mm diameter side-drilled holes (SDHs) arranged radially. The elementary signals corresponding to each individual element of the LIPA were computationally reconstructed from the acquired multiplexed signals. The resulting Full Matrix Capture (FMC) was then processed using the Total Focusing Method (TFM) algorithm to generate TFM images.