Traceable industrial 3D roughness and dimensional measurement using optical 3D microscopy and optical distance sensors (TracOptic)
Funding: EMPIR
Duration: June 2021 – June 2024
Team: Richard Leach, Helia Hooshmand, Mingyu Liu
Partners: EURAMET National Metrology Institute; Centro Ricerche Fiat S.C.p.A.; Friedrich-Alexander-Universität Erlangen – Nürnberg; Ostschweizer Fachhochschule; Fundacion Tekniker; Technische Universitaet Clausthal; Technische Universitaet Chemnitz; Technische Universität Kaiserslautern; Universitaet Kassel; Universitaet Stuttgart; Alicona Imaging GmbH; Gesellschaft für Bild- und Signalverarbeitung mbH; twip optical solutions GmbH; Universitaet Leipzig; Zygo Corporation
The overall objective of the project is to enable traceable 3D roughness and dimensional measurements using optical 3D microscopy and optical distance sensors, with special emphasis on giving guidance for selection of most suitable instrumentation for a particular purpose.
The specific objectives are:
- To determine suitable surface texture parameters of different samples: (i) available well-known roughness standards; (ii) typical technical surfaces; (iii) roughness samples produced by new manufacturing technologies; (iv) spheres with different material and roughness characteristics and (v) solid roughness samples from biology and medicine.
- To characterise the measurement capabilities of 3D optical microscopy, interferometric nanoscopy and optical distance sensors, including (i) measurable local slope distribution, (ii) bandwidth (PSD) (iii) noise, (iv) influence of BRDF (v) topography fidelity and (vi) length measurement error. Additionally, to investigate the influence of (i) measurement principle, (ii) hardware setup, (iii) feature geometries (e.g. amplitude, spatial frequency, slope distribution, curvature) and (iv) software on areal roughness and dimensional measurements.
- To develop a numerical model based on analytical models or computation models using rigours 3D Maxwell solvers for solving the light matter interaction. This should include the development of approaches for the correlation between roughness and dimensional parameters and the PSD, topography fidelity and slope distribution. Additionally, to evaluate the performance of a systematic error analysis and error correction.
- To develop and validate procedures for the selection of appropriate instrumentation for a given measurand. The target uncertainties are 5 nm (10 % deviation for 50 nm < Sq < 100 nm) for optical roughness measurements and 100 nm for optical dimensional measurements. This should include the development of methods for data evaluation and simplified uncertainty estimation.
- To facilitate the take up of the technology, measurement infrastructure and good practice guides developed in the project by the measurement supply chain, standards developing organisations and end users.
MMT will lead the optical modelling work and develop virtual instruments for coherence scanning interferometry.