Three-dimensional shape measurement of a highly reflected, specular surface with structured light method.

Area of Science:

• Optics and Photonics
• Metrology
• Computer Vision

Background:

• Measuring highly reflective and specular surfaces presents significant challenges in metrology.
• Traditional structured light methods struggle with phase ambiguity and unwrapping on such surfaces.
• Accurate 3D surface reconstruction is crucial for quality control and reverse engineering.

Purpose of the Study:

• To develop a robust mathematical model for precise 3D measurement of highly reflective, specular surfaces.
• To enhance the phase unwrapping process for improved accuracy and speed.
• To enable the measurement of complex surfaces, including step surfaces like gauge blocks.

Main Methods:

• A structured light method projecting an amplitude perturbation fringe pattern.
• Utilizing the amplitude perturbation to identify a reliable starting point for phase unwrapping.
• Employing image segmentation technology to accelerate the phase unwrapping procedure.
• Implementing a zonal wave-front reconstruction algorithm for 3D surface reconstruction.

Main Results:

• Accurate phase calculation by locking a reliable starting unwrapping point.
• Successful measurement of step surfaces with varying heights.
• Increased speed in phase unwrapping due to image segmentation.
• Demonstrated accuracy and high stability in experimental measurements of specular surfaces.

Conclusions:

• The proposed structured light method effectively measures highly reflective, specular surfaces.
• The amplitude perturbation technique significantly improves phase unwrapping reliability and accuracy.
• The method is versatile, applicable to both continuous and step surfaces.
• The developed methodology offers a stable and accurate solution for 3D surface metrology.