Design, fabrication, and characterization of single-element interdigital transducers for NDT applications

Single-element interdigital transducers (IDTs) are designed, fabricated, and characterized as a complimentary sensor approach for traditional ultrasonic transducers used in nondestructive testing (NDT). The frequency of interest is in the lower megahertz range, 2–10 MHz. In this paper, a simple five-finger paired IDT is described, where laser micro-machining techniques were used to shape the electrode patterns for an IDT resonance frequency of ∼3 MHz. Detailed characterization of the Rayleigh surface waves generated by the IDT is performed using a scanning laser interferometry system. Wave properties such as beam profile, beam divergence, energy decay, frequency response, and phase dependence are reported.