Parallel unambiguous generalized phase-shifting and T-spline fitting algorithms for optical micro-structured surface...

Area of Science:

• Optical Engineering
• Metrology
• Surface Science

Background:

• 3D topography metrology is crucial for optical micro-structured surfaces.
• Coherence scanning interferometry (CSI) is advantageous for this application.
• Existing CSI methods struggle with accurate phase shifting and surface characterization algorithms.

Purpose of the Study:

• To develop advanced algorithms for high-accuracy and efficient 3D topography metrology of optical micro-structured surfaces.
• To address limitations in phase shifting and surface characterization within CSI.

Main Methods:

• Proposed parallel unambiguous generalized phase-shifting algorithm using iterative envelope fitting with Newton's method.
• Optimized phase-shifting calculations using Graphics Processing Unit-Compute Unified Device Architecture (GPU-CUDA).
• Introduced a T-spline fitting algorithm with image quadtree decomposition for surface fitting and roughness characterization.

Main Results:

• Achieved more accurate surface reconstruction of optical micro-structured surfaces.
• Demonstrated a 10x increase in efficiency, with surface reconstruction completed in under 1 second.
• Improved roughness characterization accuracy by over 10% compared to B-spline methods.

Conclusions:

• The proposed parallel phase-shifting and T-spline fitting algorithms significantly advance 3D topography metrology for optical surfaces.
• The methods offer enhanced accuracy and efficiency for manufacturing and evaluation.
• This work provides a robust solution for complex optical surface metrology challenges.