Testing Ultrasonic Transducers with Vibrometry

This application note demonstrates how SmarAct’s PICOSCALE Vibrometer can be used to characterize ultrasonic transducers by measuring their mechanical response to electrical excitation. With high temporal resolution and confocal imaging, the system enables precise time-domain analysis on uncoated ceramic surfaces without altering transducer properties. Spatial mapping further reveals motion distribution, offering valuable insights for optimizing transducer performance.

Problem

Ultrasonic transducers are widely used in diagnostics, but their performance depends on efficient conversion of electrical to mechanical energy. Traditional testing methods struggle with small displacements and non-reflective surfaces, which are typical in ceramics or plastic-coated transducers.

Solution

SmarAct’s PICOSCALE Vibrometer, with integrated confocal optics, enables direct, high-resolution measurement on non-reflective surfaces without requiring a reflective coating. Combined with synchronized waveform triggering, it provides noise-reduced time-domain displacement data.

Implementation

• The transducer was excited using an arbitrary waveform generator, while displacement was sampled at 10 MHz.

• Up to 2000 measurements were averaged to achieve sub-nanometer resolution (~20 pm RMS).

• Motion was mapped at 16 positions across two concentric circles to analyze spatial distribution.

Results

• The system resolved vibration features well below 0.1 nm, including post-pulse reverberations.

• Spatial measurements showed significantly different responses between center and edge regions of the transducer, confirming non-uniform mechanical behavior.

Conclusion

PICOSCALE Vibrometer allows automated, non-invasive, and ultra-precise testing of ultrasonic transducers, making it ideal for detailed characterization and design optimization—without altering surface conditions or transducer geometry.