Binarized dual phase-shifting method for high-quality 3D shape measurement.

Area of Science:

• Optical metrology
• 3D surface reconstruction
• Computer vision

Background:

• 1-bit binary patterns offer speed advantages over 8-bit sinusoidal patterns in high-speed applications.
• Binary patterns, however, suffer from lower phase quality, particularly when the projector is nearly focused.
• Dual phase-shifting methods reduce phase errors but increase pattern count and reduce measurement speed.

Purpose of the Study:

• To propose a novel binarized dual phase-shifting (BDPS) method.
• To achieve high-quality phase maps using a reduced number of phase-shifted binary patterns.
• To maintain high measurement speed while improving phase accuracy in 3D profilometry.

Main Methods:

• Merging two sets of squared binary phase-shifting patterns into a single set with three gray levels.
• Employing 2D area modulation to binarize the three-gray-level patterns.
• Implementing the BDPS technique for phase error reduction in binary defocusing.

Main Results:

• The BDPS method successfully generates high-quality phase maps using only three phase-shifted binary patterns.
• Error reduction is achieved for the binary defocusing technique.
• The method maintains the speed advantage of binary patterns without increasing pattern count or bit depth.

Conclusions:

• The proposed BDPS method effectively reduces phase errors in binary pattern-based 3D measurements.
• BDPS offers a balance between measurement accuracy and speed, outperforming traditional methods.
• Validated through quantitative evaluations on both flat and complex surfaces.