CSI_PSF_measurement_correction_review_2.pdf (595.47 kB)
Coherence scanning interferometry: measurement and correction of three-dimensional transfer and point-spread characteristics
journal contribution
posted on 2018-08-31, 10:42 authored by Rahul Mandal, Jeremy CouplandJeremy Coupland, Richard K. Leach, D. MansfieldWhen applied to the measurement of smooth surfaces, coherence scanning interferometry can be described by a three-dimensional linear filtering operation that is characterized either by the point-spread function in the space domain or equivalently by the transfer function (TF) in the spatial frequency domain. For an ideal, aberration-free instrument, these characteristics are defined uniquely by the numerical aperture of the objective lens and the bandwidth of the illumination source. In practice, however, physical imperfections such as those in lens aberrations, reference focus, and source alignment mean that the instrument performance is not ideal. Currently, these imperfections often go unnoticed as the instrument performance is typically only verified using rectilinear artifacts such as step heights and lateral grids. If an object of varying slope is measured, however, significant errors are often observed as the surface gradient increases. In this paper, a new method of calibration and adjustment using a silica micro-sphere as a calibration artifact is introduced. The silica microsphere was used to compute the point-spread and TF characteristics of the instrument, and the effect of these characteristics on instrument performance is discussed. Finally, a straightforward method to correct for phase and amplitude imperfections in the TF is described using a modified inverse filter.
Funding
The authors gratefully acknowledge support and funding from Taylor-Hobson Ltd. and NPL (under the UK National Measurement System Engineering and Flow Metrology Programme) for this work.
History
School
- Mechanical, Electrical and Manufacturing Engineering
Published in
Applied OpticsVolume
53Issue
8Pages
1554 - 1563Citation
MANDAL, R. ... et al., 2014. Coherence scanning interferometry: measurement and correction of three-dimensional transfer and point-spread characteristics. Applied Optics, (8), pp. 1554 - 1563.Publisher
© Optical Society of AmericaVersion
- AM (Accepted Manuscript)
Publisher statement
This work is made available according to the conditions of the Creative Commons Attribution-NonCommercial 4.0 International (CC BY-NC 4.0) licence. Full details of this licence are available at: http://creativecommons.org/licenses/by-nc/4.0/Acceptance date
2014-01-28Publication date
2014-03-05Notes
This article was published in Applied Optics [© Optical Society of America] and the definitive version is available at: https://doi.org/10.1364/AO.53.001554. Users may use, reuse, and build upon the article, or use the article for text or data mining, so long as such uses are for non-commercial purposes and appropriate attribution is maintained. All other rights are reserved.ISSN
1559-128XeISSN
2155-3165Publisher version
Language
- en