High-speed and dense three-dimensional surface acquisition using defocused binary patterns for spatially isolated...

Area of Science:

• Optics and Photonics
• 3-D Metrology
• Image Processing

Background:

• Traditional 3-D shape measurement methods using Ronchi gratings can be limited by fringe contrast and measurement range.
• Spatially isolated objects pose challenges for accurate 3-D reconstruction.
• Defocused optical systems require robust pattern analysis techniques.

Purpose of the Study:

• To develop an improved 3-D shape measurement method for spatially isolated objects.
• To enhance measurement depth, range, and speed using defocused binary patterns.
• To enable high-speed 3-D surface acquisition for dynamic object analysis.

Main Methods:

• Utilizing defocused binary patterns generated by two Ronchi gratings with a specific positional difference.
• Employing Fourier analysis for phase distribution retrieval of fringe patterns.
• Implementing an encoded pattern with three gray levels, converted to binary via error diffusion, for fringe order identification.

Main Results:

• Achieved high contrast fringe patterns suitable for defocused optical systems.
• Eliminated third harmonic components and background illumination, expanding measurement depth and range.
• Demonstrated a 3-D surface acquisition system capable of 60 fps at 640x480 resolution and 120 fps at 320x240 resolution.

Conclusions:

• The proposed method offers a robust and efficient approach for 3-D shape measurement of isolated objects.
• The system's high-speed acquisition capabilities pave the way for analyzing dynamic phenomena.
• Further enhancements in hardware could potentially achieve measurement speeds in the thousands of frames per second.