Shear Waves are introduced using an array of piezoelectric transducers at the testing surface. Shear waves reflected from changes in acoustic impedance in the material are measured by the transducer array. With knowledge of the propagation velocity through the material, the data can be analyzed to determine the depth to internal flaws or the back surface. Data interpretation and analysis is required by experienced operators.

The MIRA system consists of an array of forty ultrasonic transducers capable of transmitting and receiving ultrasonic shear waves. The transducers are spring-loaded, dry-point contact (DPC) piezoelectric sensors with a center frequency of 50 kHz. Each transducer is built with a wear-resistant ceramic tip, which allows testing on rough surfaces. The received signals are processed by the controlling console and then transferred to a laptop computer for analysis. A synthetic aperture focusing technique (SAFT) data processing method is then performed to generate the 3-D images of the tested element. The reconstructed images are displayed as a plan view, cross-section, and isometric views.