| Issue |
J. Eur. Opt. Soc.-Rapid Publ.
Volume 15, Number 1, 2019
|
|
|---|---|---|
| Article Number | 20 | |
| Number of page(s) | 7 | |
| DOI | https://doi.org/10.1186/s41476-019-0116-1 | |
| Published online | 04 September 2019 | |
Research
Improving the calibration of phase measuring deflectometry by a polynomial representation of the display shape
1
BIAS-Bremer Institut für angewandte Strahltechnik, Klagenfurter Str.5, 28359, Bremen, Germany
2
University of Bremen, Faculty of Physics and Electrical Engineering, Otto-Hahn-Allee 1 and MAPEX Center for Materials and Processes, 28359, Bremen, Germany
Received:
28
May
2019
Accepted:
15
August
2019
Background: Phase measuring deflectometry is a highly precise and full field metrology technique for specular surfaces based on the distortion of known reference patterns observed as a reflection at the surface under test. Typically, liquid crystal displays are employed to provide the required patterns. Due to a lack of research, these displays are used without sufficient calibration.
Methods: In this work, we present an enhanced calibration for phase measuring deflectometry, taking flatness deviations of the display surface into account. The display shape is modelled as a polynomial surface whose coefficients are determined by minimizing the retrace error in a global optimization procedure during calibration. This approach does not require any additional measurements or hardware. Improvements due to the enhanced calibration model are qualified experimentally using a flat and a spherical concave mirror.
Results and conclusion: The model-based parameterization of the display surface yields significant improvement on both samples. The peak to valley (PV) of measured deviations on the plane mirror are reduced by 67% to 0.55 μm. Measuring the spherical sample without the display parameterization leads to a rather large shape deviation of 33.40 μm PV which is reduced by 94% to 1.98 μm. The viability of our approach confirms the dominant role of flatness deviations of the display surface as an error source in absolute shape measurement using phase measuring deflectometry.
Key words: Deflectometry / Absolute surface metrology / Displays
© The Author(s) 2019
Open Access This article is distributed under the terms of the Creative Commons Attribution 4.0 International License (http://creativecommons.org/licenses/by/4.0/), which permits unrestricted use, distribution, and reproduction in any medium, provided you give appropriate credit to the original author(s) and the source, provide a link to the Creative Commons license, and indicate if changes were made.
Current usage metrics show cumulative count of Article Views (full-text article views including HTML views, PDF and ePub downloads, according to the available data) and Abstracts Views on Vision4Press platform.
Data correspond to usage on the plateform after 2015. The current usage metrics is available 48-96 hours after online publication and is updated daily on week days.
Initial download of the metrics may take a while.