Revisiting optical scattering and machine learning (SPARKLE)

This collaboration with the University of Nottingham focuses on developing optical instrumentation to assess the surface quality of the machined parts during the manufacturing process.

Our aim

The surface topography of a component part can have a profound effect on the function of the part. It is estimated that the surface effects cause 10% of manufactured parts to fail. In tribology, it is the microscopic surface interactions that influence such quantities as friction, wear and the lifetime of a component. In fluid dynamics, surface characteristics influence macroscopic properties like aerodynamic lift, directly affecting the efficiency and fuel consumption of aircraft.

The overall aim of this work is to demonstrate a simple and cost-effective measurement system that uses artificial intelligence (AI) to classify a machined surface according to its scattered light signature. As part of the collaboration, we have provided a comprehensive vector solution to surface scattering, which models sensor outputs and provides an accurate, complete dataset for AI purposes.

Our research

The solution we have developed represents the scattered (and transmitted) fields as expansions of dipole sources positioned at the boundary surface. To calculate the strength of these sources we apply the extinction theorem of Ewald and Oseen at points placed just inside and outside of the boundary surface according to the Nyquist sampling criteria. The method that we call 3sBSM accurately accounts for polarisation, multiple scattering and surface plasmon resonances when they occur.

Our outcomes

The 3sBSM method and its fundamental relationship to Huygens’ principle is explained in the article: Optics Express Vol. 27(21) pp. 30380-30395  (2019)

Our sponsors

We gratefully acknowledge the Engineering and Physical Sciences Research Council (EP/R028842/1) and our industrial partners Renishaw, Zygo, Xaar and Zeeko for supporting this work.

 

“We proved that by using Ewald and Oseen extinction theorem, a 3D vector formulation of Huygens’ principle can be used to calculate light scattered from the surface, without any significant mathematical complication.”

Project Lead - Jeremy Coupland