Optical Characterization of Materials for Precision Reference Spheres for Use with Structured Light Sensors

Area of Science:

• Metrology
• Optical Engineering
• Materials Science

Background:

• Non-contact 3D digitizing sensors, particularly structured light sensors, are increasingly adopted due to limitations of traditional contact measurement methods.
• The metrological performance of structured light sensors is significantly influenced by the optical properties of the digitized material.
• A lack of standardized calibration artifacts necessitates characterization studies for validating sensor performance.

Purpose of the Study:

• To optically characterize and compare various materials and surface finishes of reference spheres for structured light sensor calibration.
• To determine the optimal sphere material-sensor combination for different application fields.
• To evaluate the suitability of different spheres as registration targets in 3D digitizing.

Main Methods:

• Comparison of different materials and surface finishes of reference spheres.
• Optical characterization of spheres using two structured light sensors with distinct application fields.
• Utilizing a Coordinate Measuring Machine (CMM) contact measurement system as a reference.
• Analysis of two different filters for processing sensor data.

Main Results:

• Sandblasted stainless steel spheres demonstrated superior performance for calibrating and qualifying structured light sensors.
• These spheres are also highly effective as registration targets in 3D digitizing processes.
• Tungsten carbide and zirconium spheres were found to be unsuitable for sensor calibration and digitizing applications.

Conclusions:

• Sandblasted stainless steel spheres are the recommended choice for calibrating and qualifying structured light sensors.
• The selection of appropriate sphere material is critical for achieving accurate metrological performance.
• Further research into standardized artifacts is needed to ensure reliable sensor qualification.