Accurate calibration for crosstalk coefficient based on orthogonal color phase-shifting pattern.

Area of Science:

• Optical Metrology
• 3D Imaging Systems
• Color Image Processing

Background:

• Color fringe projection profilometry (CFPP) is vital for accurate 3D surface measurements.
• Color crosstalk in camera channels degrades measurement accuracy.
• Existing calibration methods often rely on modulation calculations, which can be less robust.

Purpose of the Study:

• To propose a novel approach for calibrating the crosstalk matrix in color cameras for CFPP.
• To establish a wrapped phase error model accounting for color crosstalk.
• To enable high-accuracy 3D measurements by effectively mitigating crosstalk effects.

Main Methods:

• A new method calibrates crosstalk coefficients using phase error, not modulation.
• Designed color orthogonal phase-shifting fringe patterns are projected onto a white plate.
• Phase-shifting fringe patterns in horizontal and vertical directions are separated from captured images.
• Crosstalk coefficients are calibrated by fitting the error relationship between standard and crosstalk-affected wrapped phases.

Main Results:

• The proposed method successfully calibrates the crosstalk matrix of a color camera.
• Simulations and experimental validations confirm the method's effectiveness.
• Accurate shape and distance measurements were achieved on a white plate and a step block, respectively.

Conclusions:

• The novel phase error-based calibration method effectively addresses color crosstalk in CFPP.
• This approach enhances the accuracy of 3D measurements in color fringe projection systems.
• The validated method offers a reliable solution for de-crosstalking in optical metrology.