We propose a nondestructive evaluation method for immersed structures based on the
propagation of ultrasonic waves induced by means of laser pulses and detected with an
array of immersion transducers. In the study presented in this article, a laser operating at
532nm is employed to excite leaky guided waves on an aluminum plate immersed in water.
An array of immersion transducers is used to record the waves radiating from the
laser-illuminated point. The detected signals are processed with an imaging algorithm based
on continuous wavelet transform and probabilistic analysis to localize the presence of artificial
defects machined in the plate. With respect to the existing imaging methods for plates,
the proposed algorithm is pseudo baseline free, because it does not require data recorded
from a pristine plate, but it requires that only a portion of the plate is free from defects. We
find that the proposed algorithm enables the detection of surface cracks. Advantages and
limitations of the algorithm for the nondestructive evaluation of underwater structures are
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