On-line metrology with conoscopic holography: beyond triangulation

Area of Science:

• Optical Metrology
• Interferometry
• Surface Inspection

Background:

• High-precision, on-line, non-contact surface inspection remains a challenge.
• Laser triangulation has limitations in precision, standoff, aperture, and harsh conditions.
• Existing methods are often unsuitable for hostile environments or real-time measurement.

Purpose of the Study:

• To review the latest advancements in Conoscopic Holography for surface inspection.
• To highlight its applicability in scenarios where traditional methods fail.
• To showcase its potential for high-precision metrology in demanding industrial settings.

Main Methods:

• Review of research on Conoscopic Holography.
• Analysis of its interferometric principles for surface measurement.
• Evaluation of its performance in diverse applications.

Main Results:

• Conoscopic Holography successfully addresses limitations of laser triangulation.
• Demonstrated sub-micrometric roughness measurements.
• Proven effective for long-standoff sensors, including high-temperature steel defect detection.

Conclusions:

• Conoscopic Holography is a viable and advanced solution for on-line, non-contact surface inspection.
• It offers superior performance in challenging industrial environments.
• Its versatility spans from micro-scale roughness to macro-scale defect detection.