Air-Coupled Ultrasonic Probe Integrity Test Using a Focused Transducer with Similar Frequency and Limited Aperture...

Area of Science:

• Materials Science
• Acoustics
• Non-Destructive Testing

Background:

• Air-coupled ultrasonic probes are susceptible to damage due to their soft matching layers and electrical degradation.
• Ensuring the integrity of these probes during design, manufacturing, and use is crucial for reliable performance.
• Existing inspection methods face challenges with degraded contrast and resolution due to the small scanning beam area relative to the probe size.

Purpose of the Study:

• To develop an effective method for inspecting the integrity of air-coupled ultrasonic probes.
• To enhance the contrast and lateral resolution of imaging during probe integrity inspection.
• To enable the detection of both natural and artificial defects in air-coupled ultrasonic probes.

Main Methods:

• Spatial distribution of transduction efficiency over the piezoelement surface was used for inspection.
• A focused transducer of similar center frequency scanned the inspected probe's surface.
• A masking aperture made from cardboard and felt was implemented at the focal point to suppress sidelobes.

Main Results:

• The masking aperture effectively suppressed far-range sidelobes to the noise floor (-50 dB) and near-range sidelobes to -17 dB.
• The proposed modification allows the use of a similar frequency focused transducer for inspection.
• Significantly enhanced contrast and lateral resolution were achieved for probe integrity inspection.

Conclusions:

• The developed method provides a convenient means for air-coupled ultrasonic probe integrity inspection.
• The masking aperture technique overcomes resolution and contrast limitations of previous approaches.
• The method facilitates the detection of defects, improving the reliability and longevity of air-coupled ultrasonic probes.