Selecting the Pitch of a Double Crystal Transducer in Ultrasonic Testing of Products Made of Complex Structured Materials with a Nonplanar Surface

Abstract

It is noted that the ultrasonic testing of products made of complex structured materials is based, as a rule, on spatiotemporal signal processing, using ultrasonic antenna arrays to extract useful echo signal from pattern noise. If the product has a nonplanar surface, one should use a synthesized aperture antenna, which is a double crystal transducer (DC PET) moved along the product surface in steps of d. The dependence of the cross-correlation of pattern-noise instances on the distance between two DC PET positions was established and used to determine the optimum (maximizing the signal–to–pattern-noise ratio) DC PET movement step d, depending on transducer’s aperture size.