Ultrasound Burst Phase Thermography (UBP)

Being a pulse thermography method, ultrasound burst phase thermography* (UBP) combines the advantages of lockin and pulse thermography. Short ultrasound bursts (wave trains, length 10...1000ms) are used to excite the sample. The temperature development of heating-up and cooling-down afterwards is grabbed by a thermography camera and fourier-transformed. Thereby one obtains - as with lockin methods - phase images with their typical properties (suppression of temperature gradients and determination of defect depths).

Another advantage of burst excitation, compared to excitation with one sinusoidal frequency, is the broad thermal response spectrum. Therefore it is possible to analyse different modulation frequencies with only one measurement, which would take several successive measurements with sinusoidal excitation. The decay behaviour, and hence the range of the thermal wave, depends on the used frequency. Therefore the phase image gives direct information about the defect depth in the component, significant shortening of the measurement period and enhanced evaluation reliability at the same time.

*patent DE 100 59 854.4