Fourier-domain post-processing technique for Digital Focus Array imaging with Matrix phased array for ultrasonic testing of ITER components

•We propose the new ultrasonic imaging technique for Digital Focus array imaging with Matrix array probes.•The technique is based on the Fast Fourier transform of ultrasonic data and calculations in frequency domains.•Our suggested technique can be used for ultrasonic immersion testing of the ITER components. The high demands on the quality of the components of the International Thermonuclear Experimental Reactor (ITER) create the need to apply methods of nondestructive testing which are able to provide accurate and reliable results. One such technique is Digital Focus Array ultrasonic imaging with Matrix phased arrays. The application of this approach is linked with the need to process huge sets of data in order to obtain images of controlled objects. In this article, we propose the technique of computationally efficient Fourier-domain post-processing. This algorithm is based on Fast Fourier transformations and calculations in frequency domains and can be applied in immersion and contact testing. The performance of this technique was examined experimentally.