Ultrasonic transducers, contact single element
Single element contact probes use the same piëzo-electric element for transmitting and for receiving ultrasonic signals. Applications range from thickness measurements to detection of surface indications.
Ultrasonic wave types
For inspections with transversal waves, most of the time single element contact probes are used. The biggest advantage of these probes is that interpretation of the signals is easier, because no longitudinal wave is generated by the probe. High angled transversal wave probes generate surface waves for detection of surface defects.
Longitudinal wave probes are used for the inspection of materials with high material scattering (for example: coarse grained austenitic materials) of techniques which make use of tip diffraction (example: TOFD).
High angled longitudinal wave probes also generate creeping waves, which can be used for the detection of (near-)surface defects.
These probes are available in frequencies from 0.5 to 15 MHz, with bandwidth low, medium or high. All designs of housings are possible as long as all necessary components will fit in.
Probes can be designed with curved elements for focusing purposes or for use under special conditions.
For applications where a better signal to noise ratio is needed or defect orientation plays a role, dual element contact probes are often used.