An Iterative Deflectometry Method of Reconstruction of Separate Specular Surfaces

Area of Science:

• Optical Metrology
• Surface Metrology
• Computer Vision

Background:

• Phase measuring deflectometry (PMD) is crucial for specular surface measurement.
• Existing methods struggle with discontinuous surfaces.
• Stereoscopic PMD offers potential for advanced surface reconstruction.

Purpose of the Study:

• To develop a robust surface reconstruction method for both continuous and discontinuous specular surfaces.
• To enhance the accuracy and noise resistance of PMD measurements.
• To utilize stereoscopic PMD for iterative surface reconstruction.

Main Methods:

• Implementation of a stereoscopic phase measuring deflectometry (PMD) system.
• Development of an iterative reconstruction mechanism using pre-known reflecting point coordinates.
• Application of B-spline surfaces for their local property advantages.
• Mathematical analysis to improve noise resistance and accuracy.
• Scaling of B-spline surfaces using sparse point clouds from stereoscopic PMD.

Main Results:

• A novel reconstruction method applicable to both continuous and discontinuous specular surfaces.
• Improved accuracy and robustness in surface reconstruction compared to existing methods.
• Successful validation through simulated and experimental tests.
• Demonstrated noise resistance through mathematical analysis and sparse point cloud scaling.

Conclusions:

• The proposed iterative reconstruction method using stereoscopic PMD is highly accurate and robust.
• This technique effectively addresses the limitations of measuring discontinuous specular surfaces.
• The B-spline surface approach combined with sparse point cloud scaling enhances measurement precision.