Application of a Double Scanning Method in Ultrasonic Nondestructive Testing to Improve the Quality of Flaw Images

An algorithm for obtaining flaw images by a double scanning method for application in ultrasonic nondestructive testing, in which a radiator and a receiver move independently along parallel straight lines, is considered. A formula for reconstruction of flaw images is presented. The advantages and drawbacks of the double scanning method are discussed in comparison with the method of projection in the spectral space (PSS), which is also used for a coherent reconstruction of flaw images. The efficiency of the double scanning technique in suppressing the phantom images produced by transformed and rescattered pulses is shown in numerical and model experiments. The immunity of this method to the distortions introduced by an irregular measurement surface and the higher noise immunity compared to the PSS method are also demonstrated.