Improved signal model for confocal sensors accounting for object depending artifacts

Area of Science:

• Optical metrology
• Surface characterization
• Sensor technology

Background:

• Confocal sensors are widely used for surface measurements due to their robustness, particularly on rough surfaces.
• The established signal model is derived assuming planar surfaces or point-like objects, limiting its applicability.
• Measurement artifacts have been observed when using confocal sensors on curved surfaces.

Purpose of the Study:

• To investigate and explain the origin of artifacts in confocal point sensor measurements of curved surfaces.
• To extend the conventional confocal sensor signal model to account for curved geometries.
• To provide a qualitative explanation for observed measurement deviations.

Main Methods:

• Experimental measurement of a surface standard using a confocal point sensor.
• Analysis of measurement data to identify and characterize artifacts on curved sections.
• Development and application of an extended signal model to interpret the experimental results.

Main Results:

• Experimental data clearly demonstrates the emergence of significant artifacts during confocal point sensor measurements of curved surfaces.
• The extended signal model successfully explains the qualitative behavior of these artifacts.
• Deviations from the conventional model are directly linked to the surface curvature.

Conclusions:

• The conventional confocal sensor signal model is insufficient for accurately measuring curved surfaces.
• An extended signal model provides a framework for understanding and potentially mitigating artifacts on curved geometries.
• This work advances the understanding of confocal sensor limitations and opens avenues for improved measurement accuracy on complex surfaces.