Here is a comparison of a linear scanning using 8 elements focused close to the backwall and a TFM using 64 elements with 5L64 probe. The gain is set to have a backwall at 300% for both acquisition. We are looking at a 1-mm and a 4-mm conical holes machined in a 10-mm steel plate by Sonaspection. We can see that the TFM is not only able to detect the 4-mm hole but it also draws its shape. This is due to the fact that we fire one element at a time; so the energy is sent in all directions and part of it reaches the hole normal to its conical shape. For the L0 linear scanning, the energy is reflected away and it is hard to see the hole. The 1-mm pitting is detected with a 24 dB SNR for the TFM and not seen by the electronic scan. The Mantis is used here with the Master option which permits to use 64-element TFM (same as GEKKO).
#TFM #Mantis #Gekko #pitting #corrosion