A novel encoded-phase technique for phase measuring profilometry.

Area of Science:

• Optics and Photonics
• Computer Vision
• Metrology

Background:

• Traditional 3-D shape measurement techniques often require complex setups or multiple fringe patterns.
• Phase unwrapping can be challenging, especially in areas with phase jumps or for spatially isolated objects.

Purpose of the Study:

• To propose and validate a novel encoded-phase grating method for accurate three-dimensional (3-D) shape measurement.
• To overcome limitations of existing methods by integrating encoded information directly into fringe patterns.

Main Methods:

• Utilizing sinusoidal fringe patterns with wrapped and encoded phase, instead of monotonic and unwrapped phase.
• Employing the phase-shift technique for evaluating fringe phase values on the object surface.
• Restoring absolute phase using encoded information extracted from the differential of the wrapped phase.
• Applying the Hilbert transform to mitigate phase errors in phase-jump areas.

Main Results:

• Demonstrated feasibility of the encoded-phase grating technique through experimental validation.
• Successfully measured the 3-D shape of spatially isolated objects.
• Eliminated the need for projecting additional patterns by embedding encoded information within the wrapped phase.

Conclusions:

• The proposed encoded-phase grating method offers a robust and efficient approach for 3-D shape measurement.
• The technique shows significant potential for analyzing dynamic objects and complex surface geometries.
• This advancement simplifies 3-D measurement systems and expands their applicability.