| Zugriffsnummer | 22308 |
| Dokumenttyp | Konferenzartikel |
| Sprache | Englisch |
| Titel | Distance-dependent influences on angle metrology with autocollimators in deflectometry |
| Autor(in); Institution |
Geckeler, Ralf D.; 5.2, Dimensionelle Nanometrologie, PTB-Braunschweig
Just, Andreas; 5.2, Dimensionelle Nanometrologie, PTB-Braunschweig
|
| Quelle/Jahr | Advances in x-ray/EUV optics and components III:(2008), 70770B-1 - 70770B-12 |
| Schriftenreihe | Proceedings of SPIE: 7077 |
| Herausgeber(in) |
Kounsary, Ali M.
|
| ISBN | 978-0-8194-7297-7 |
| DOI | |
| Verlag | Bellingham, Wash.: SPIE |
| Konferenzangaben | Advances in X-Ray/EUV Optics and Components III, San Diego, California, 11-13, August, 2008, USA |
| Freie Schlagworte | autocollimator ; deflectometry ; angle ; angle calibration ; traceability ; precision metrology |
| Zusammenfassung | The application of electronic autocollimators to the deflectometric measurement of synchrotron optics in beamline metrology laboratories is steadily increasing. The main reason is the availability of commercial high-resolution autocollimators capable of providing highly stable angle metrology down to aperture sizes of 1-2 mm even for uncoated optical surfaces. The measuring beam of the autocollimator not only provides the straight propagation of light as a natural straightness standard. Tracing back the angle measurement to primary standards via calibration also enables to measure surface shape without any recourse to material straightness artifacts. At the Physikalisch-Technische Bundesanstalt (PTB), the Working Group 5.23 "Angle Metrology" provides the traceability of angle measurements by autocollimators to the radian (rad), the SI unit of the plane angle, by use of its WMT 220 angle comparator. The fundamental principle of this comparator is the subdivision of the circle, representing an error-free natural standard of 2 π rad. It is realized by various self- and cross-calibration methods. Autocollimators are calibrated by direct comparison with this primary standard with very low uncertainty. As the aperture sizes of autocollimators decrease, issues such as the transferability / applicability of the calibration to the measurement conditions in the deflectometric set-up become more and more significant. In this paper we are focusing on the investigation of the influence of the distance between the autocollimator and the surface under test on its angle response. Information on the optimized use and accurate calibration of autocollimators for deflectometric applications is provided. |
