Quick pre-correction of a grating fringe for phase measuring profilometry.

Area of Science:

• Optical Metrology
• 3D Reconstruction
• Image Processing

Background:

• Phase Measuring Profilometry (PMP) systems using digital light projectors often face geometric distortions (keystone, period broadening) in real-world applications.
• Traditional calibration methods struggle to fully eliminate these grating fringe distortions on the reference plane.
• System geometry limitations are often impractical in actual engineering conditions, necessitating robust correction techniques.

Purpose of the Study:

• To propose a novel, quick pre-correction method for grating fringes in digital light projector-based PMP systems.
• To address and individually correct keystone and period broadening distortions that are difficult to eliminate traditionally.
• To develop a correction method compatible with existing PMP calibration techniques and applicable without special targets.

Main Methods:

• An analytic spatial transform-based pre-correction method is designed.
• The correction is applied before generating the digital micromirror device image.
• The method involves projecting and capturing a fringe pattern and a corner pattern for rapid calibration.

Main Results:

• The proposed method effectively corrects keystone and period broadening distortions in grating fringes.
• Simulations and experiments confirm the method's effectiveness.
• The correction process is quick, completed within seconds, and requires no special calibration target.

Conclusions:

• The novel grating fringe pre-correction method offers a practical solution for PMP systems operating under non-ideal geometric conditions.
• This analytic spatial transform approach enhances the accuracy and applicability of PMP in engineering.
• The method's simplicity, speed, and compatibility make it a valuable advancement in optical metrology.