A circularly focused and scanned acoustic scanner

Area of Science:

• Acoustic imaging
• Ultrasonic transducer technology
• Non-destructive testing

Background:

• Conventional acoustic imaging systems often face limitations in electronic scanning and focusing capabilities.
• Developing advanced transducers is crucial for enhancing acoustic imaging performance.

Purpose of the Study:

• To introduce a new electronically scanned and focused acoustic imaging device: the cylindrical grating acoustic scanner.
• To present a novel transducer, the circular-edge-bonded transducer (CEBT), for generating surface acoustic waves.

Main Methods:

• Fabrication of a cylindrical substrate with an array of grooves acting as a scattering grating.
• Generation of a chirped surface-wave pulse using the CEBT.
• Coherent scattering of the surface wave into a focused bulk-wave ring that scans at surface-wave velocity.

Main Results:

• A 2.3-MHz circular scanner with a 25-cm field of view and 2.6-mm resolution was successfully constructed and tested.
• The device demonstrated adjustable focal length and resolution by modifying chirp rate and time-bandwidth product.
• An acoustic image of an artificial defect in an aluminum pipe was successfully obtained.

Conclusions:

• The cylindrical grating acoustic scanner represents a new approach to electronically steered and focused acoustic imaging.
• The CEBT and grating design enable precise control over acoustic beam focusing and scanning.
• This technology shows promise for advanced non-destructive testing and acoustic imaging applications.