The invention is a method of non-destructive testing of open cracks based on lens-free imaging.
It involves illuminating the surface to be inspected with a spatially coherent laser beam and collecting the reflected laser beam on a spatial detector in the far field. An initial, rapid scanning step identifies areas of interest that generate an additional diffracted signal.
A fine scan is then performed around these zones, recording the diffraction patterns measured at each position. The image of the inspected area is then reconstructed using digital ptychography-type algorithms to identify any open cracks.
