The random phase transducer in ultrasonic nondestructive testing of coarse grain stainless steel: An original tool to characterize multiple scattering effect

Ultrasonic nondestructive testing of cast stainless steel is difficult due to a high level speckle noise generated by the coarse grain structure. Multiple scattering of acoustic waves, explains deteriorations of focusing beyond about 2 MHz. Random phase transducers that are shown to be useful in controlling such materials are presented. Their ability to reduce speckle noise is linked to the quantity of uncorrelated information measured by the transducer. Experimental results are compared with those obtained with a standard spatial compounding technique. These results show the efficiency of the random phase transducer in order to characterize the multiple scattering effect