Laser ultrasonic imaging of subsurface defects with the linear sampling method.

Area of Science:

• Materials Science
• Non-destructive Evaluation
• Ultrasonic Testing

Background:

• Laser ultrasonics offers remote, non-contact measurement capabilities.
• Real-time monitoring is crucial for semiconductor metrology and advanced manufacturing.
• Subsurface defect detection requires high-fidelity imaging techniques.

Purpose of the Study:

• To investigate laser ultrasonic data processing for subsurface imaging.
• To reconstruct images of side-drilled holes in aluminum alloy specimens.
• To evaluate the effectiveness of the linear sampling method (LSM).

Main Methods:

• Utilized laser ultrasonics for remote ultrasonic wave generation and detection.
• Applied model-based linear sampling method (LSM) for data processing.
• Performed simulations and experimental validation on aluminum alloy samples.

Main Results:

• LSM accurately reconstructed the shape of single and multiple subsurface holes.
• Simulations demonstrated well-defined boundaries in reconstructed images.
• Experimental results confirmed LSM's ability to reveal internal geometric features missed by conventional imaging.

Conclusions:

• Laser ultrasonics with LSM is a powerful technique for non-destructive evaluation.
• LSM provides accurate subsurface imaging of internal geometric features.
• This method enhances defect detection in advanced manufacturing and metrology.