Compact scanning confocal chromatic sensor enabling precision 3-D measurements

Area of Science:

• Optical Engineering
• Robotics
• Metrology

Background:

• Precision 3-D surface measurement is crucial for robotic applications.
• Existing sensors may lack the required combination of speed, resolution, and compactness.
• Confocal chromatic sensing offers high axial resolution but typically requires mechanical scanning.

Purpose of the Study:

• To develop and validate a compact and lightweight scanning confocal chromatic sensor (SCCS) for robot-based 3-D surface measurement.
• To integrate a 2-D fast steering mirror (FSM) with a 1-D confocal chromatic sensor (CCS) for enhanced scanning capabilities.
• To achieve high-speed, high-resolution 3-D surface reconstruction for arbitrary regions of interest.

Main Methods:

• Integrated system design combining a 2-D fast steering mirror (FSM) and a 1-D confocal chromatic sensor (CCS).
• Data-driven calibration procedure to correlate FSM deflection angles with measured distances for 3-D reconstruction.
• Application of Lissajous scan trajectories for efficient surface area coverage.
• Resolution assessment using a calibration standard with defined structures.

Main Results:

• The SCCS system successfully provides 3-D surface images at frame rates up to 1 fps.
• Achieved a measurement volume of 0.35×0.25×1.8 mm³ with the capability to measure arbitrary regions.
• Determined lateral resolution of 2.5 µm and axial resolution of 76 nm using a calibration standard.

Conclusions:

• The developed SCCS is a compact and lightweight solution for robot-based precision 3-D surface measurement.
• The integrated FSM and CCS design, coupled with data-driven calibration, enables efficient and accurate 3-D surface reconstruction.
• The sensor's high resolution and frame rate make it suitable for demanding metrology applications in robotics.