Estimation of measurement uncertainty caused by surface gradient for a white light interferometer

Area of Science:

• Metrology
• Optical Engineering
• Surface Metrology

Background:

• Scanning white light interferometry (SWLI) offers sub-nanometer resolution but suffers from measurement inaccuracies.
• Surface characteristics like roughness and gradient significantly impact SWLI measurement uncertainty.
• Existing methods struggle to precisely quantify uncertainty arising from steep surface gradients within a single pixel.

Purpose of the Study:

• To develop and validate a novel uncertainty estimation method for SWLI.
• To specifically address and quantify measurement uncertainty introduced by workpiece surface gradients.
• To provide a convenient tool for determining measurement uncertainty in SWLI.

Main Methods:

• Development of a mathematical uncertainty estimation model based on SWLI principles.
• Derivation and experimental verification of the proposed uncertainty model.
• Comparison of predicted uncertainty values with experimental measurements.

Main Results:

• The developed uncertainty estimation method effectively quantifies errors due to surface gradients.
• Experimental validation shows strong agreement between the model's predictions and actual measurement uncertainty.
• The method demonstrates high accuracy in predicting uncertainty caused by surface gradients.

Conclusions:

• The proposed method provides a reliable and convenient way to estimate SWLI measurement uncertainty.
• Accurate uncertainty quantification enhances the trustworthiness of SWLI measurements for critical applications.
• This work contributes to improving the overall accuracy and reliability of optical metrology techniques.