Optical coherence tomography for process control of laser micromachining.

Area of Science:

• Materials Science
• Optical Engineering
• Non-destructive Testing

Background:

• Ablative laser processing requires precise monitoring for quality control.
• Traditional surface analysis methods can be time-consuming and destructive.
• In situ characterization is crucial for complex or delicate materials.

Purpose of the Study:

• To present in situ surface imaging using optical coherence tomography (OCT) for nondestructive evaluation (NDE) during ablative laser processing.
• To demonstrate the utility of OCT for analyzing challenging samples like optical fibers.
• To compare OCT imaging with established microscopy techniques.

Main Methods:

• Utilized optical coherence tomography (OCT) for real-time surface imaging.
• Performed ablative laser processing on various samples, including optical fibers.
• Compared OCT images with those obtained from scanning electron microscopy (SEM), reflected-light microscopy, and confocal microscopy.

Main Results:

• Achieved an axial resolution of approximately 126 nm for surface detection.
• Obtained a lateral resolution better than 2.5 micrometers.
• Demonstrated OCT's capability to image high-aspect-ratio structures effectively.
• Showcased the advantage of in situ OCT for difficult-to-handle samples.

Conclusions:

• In situ OCT is a powerful NDE tool for ablative laser processing.
• OCT provides high-resolution surface imaging comparable to SEM and other microscopy techniques.
• The technique is particularly advantageous for analyzing delicate or complex microstructures in real-time.