Improved method for rapid shape recovery of large specular surfaces based on phase measuring deflectometry

Area of Science:

• Optics and Photonics
• Metrology
• Computer Vision

Background:

• Accurate 3D shape reconstruction of specular surfaces is crucial for optical metrology.
• Existing modal and zonal estimation methods have limitations in accuracy, convergence speed, and error rejection.

Purpose of the Study:

• To develop an improved 3D shape reconstruction method for specular surfaces.
• To enhance accuracy, convergence speed, and robustness in practical applications.

Main Methods:

• A unifying scheme combining modal and zonal estimation approaches.
• Utilizing modal estimation for initial coarse height information.
• Employing a modified zonal wavefront reconstruction algorithm with successive over-relaxation for iterative refinement.

Main Results:

• Achieved a fourfold increase in convergence rate compared to existing zonal methods.
• Demonstrated three orders of magnitude improvement in reconstruction accuracy over modal techniques.
• Reduced computation time by approximately 74.92% and achieved a surface error of 6.68 μm on an experimental sphere mirror.

Conclusions:

• The proposed method offers a significant advancement in 3D specular surface shape reconstruction.
• It provides a stable, robust, and efficient real-time approach for practical applications.
• Validates the method's efficiency and accuracy through numerical simulations and experimental measurements.