Quantifying height of machined steps on copper disk using Fourier domain short coherence interferometer

Risto Montonen; Ivan Kassamakov; Edward Hæggström; Kenneth Österberg

doi:10.1117/12.2184715

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22 June 2015 Quantifying height of machined steps on copper disk using Fourier domain short coherence interferometer

Risto Montonen, Ivan Kassamakov, Edward Hæggström, Kenneth Österberg

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Proceedings Volume 9525, Optical Measurement Systems for Industrial Inspection IX; 95253L (2015) https://doi.org/10.1117/12.2184715
Event: SPIE Optical Metrology, 2015, Munich, Germany

Abstract

The internal shape and alignment of accelerator discs is crucial for efficient collider operation in the possible future compact linear collider. We applied a custom made and calibrated Fourier domain short coherence interferometer to measure the height of 40 and 60 μm machined steps on a copper disc in our laboratory. The step heights were determined to be: (43.0 ± 3.1) μm and (46.5 ± 3.2) μm for the 40 μm nominal step, and (46.6 ± 3.6) μm for the 60 μm nominal step. The errors represent 95% confidence level uncertainties and include uncertainty contributions from the calibration, refractive index of air, cosine error, and surface roughness. The step heights were validated by a calibrated contact stylus profilometer which resulted into (44.5 ± 0.8) μm and (45.9 ± 1.0) μm for the 40 μm nominal step, and (45.5 ± 1.7) μm for the 60 μm nominal step at 95% confidence level. The results show feasibility for noncontacting absolute shape and step height characterization with micrometer-level accuracy. This instrument is a first step towards a quality assurance tester for the accelerating structures of the compact linear collider.

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Risto Montonen, Ivan Kassamakov, Edward Hæggström, and Kenneth Österberg "Quantifying height of machined steps on copper disk using Fourier domain short coherence interferometer", Proc. SPIE 9525, Optical Measurement Systems for Industrial Inspection IX, 95253L (22 June 2015); https://doi.org/10.1117/12.2184715

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