Surface measuring coherence scanning interferometry beyond the specular reflection limit

Thomas, Matthew; Su, Rong; de Groot, Peter; Coupland, Jeremy; Leach, Richard

Abstract

The capability of optical surface topography measurement methods for measurement of steep and tilted surfaces is investigated through modelling of a coherence scanning interferometer. Of particular interest is the effect on the interference signal and measured topography when tilting the object at angles larger than the numerical aperture slope limit (i.e. the specular reflection limit) of the instrument. Here we use theoretical modelling to predict the results across a range of tilt angles for a blazed diffraction grating. The theoretically predicted interference patterns and surface height measurements are then verified directly with experimental measurements. Results illustrate the capabilities, limitations and modelling methods for interferometers to measure beyond the specular reflection limit.

Citation

Thomas, M., Su, R., de Groot, P., Coupland, J., & Leach, R. (2021). Surface measuring coherence scanning interferometry beyond the specular reflection limit. Optics Express, 29(22), 36121-36131. https://doi.org/10.1364/OE.435715

• Journal Article Type: Article
• Acceptance Date: Aug 10, 2021
• Online Publication Date: Oct 19, 2021
• Publication Date: Oct 25, 2021
• Deposit Date: Aug 27, 2021
• Publicly Available Date: Oct 19, 2021
• Journal: Optics Express
• Electronic ISSN: 1094-4087
• Publisher: Optical Society of America
• Peer Reviewed: Peer Reviewed
• Volume: 29
• Issue: 22
• Pages: 36121-36131
• DOI: https://doi.org/10.1364/OE.435715
• Keywords: Atomic and Molecular Physics, and Optics
• Public URL: https://nottingham-repository.worktribe.com/output/6094966
• Publisher URL: https://www.osapublishing.org/oe/fulltext.cfm?uri=oe-29-22-36121&id=461910