Working frequency: 3-5 MHz; dimensions: Ø33, height: 66 mm
Electromagnetic acoustic probes (EMAP) are used for ultrasonic thickness measurement and flaw detection. The advantage of the EMA method is ultrasonic inspection of objects without contact fluid application, as well as working with materials that have a contaminated surface (rust, corrosion, etc.) or paint coatings.
EMA probes use directional transverse SH waves (radial and linear polarization) and Lamb-waves (horizontal at right angles). Generation and reception of ultrasonic waves in test material is achieved due to influence of magnetic fields and eddy currents on it. Shear waves (going normally to the surface) propagate at a lower speed than longitudinal waves, which increases resolution when monitoring by echo method. This property has been used in thickness measurement. Shear waves with high sensitivity even detect cracks whichhave a parallel orientation to the axis ofsounding, which are "invisible" for conventional ultrasonic PZT.
Along with the obvious advantages of EMAP compared to conventional PZT their disadvantage is low sensitivity and noise immunity.