Applying the Algorithm of Calculation in the Frequency Domain to Ultrasonic Tomography of Layered Inhomogeneous Media Using Matrix Antenna Arrays

To ensure the high speed of composing synthesized images with matrix antenna arrays, industrial ultrasonic-tomography systems require computationally efficient spatiotemporal signal-processing algorithms. FFT-based algorithms with calculations in the frequency domain are of great interest in this connection. At the same time, the algorithms must output high-quality results under various conditions of ultrasonic tomography. In ultrasonic tomography of multilayered structures, the nonparallelism and, in the limiting case, curvilinearity of the boundaries of layers in the test object relative to the scanning plane is one of the factors seriously reducing the algorithm efficiency. In this article, we propose an algorithm for calculating three-dimensional tomographic images in the frequency domain using matrix phased arrays with compensation for the tilt of the test object relative to the scanning plane when using an immersion acoustic-contact technique. The effectiveness of the proposed method has been confirmed experimentally.