Open AccessInfluence of mounting on the optical surface figure in optical reference surfaces
Author(s) -
Vít Lédl,
Ines Fortmeier,
Pavel Psota,
Michael Schulz,
Ondřej Matoušek,
Roman Doleček
Publication year - 2020
Publication title -
journal of instrumentation
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.741
H-Index - 84
ISSN - 1748-0221
DOI - 10.1088/1748-0221/15/01/p01005
Subject(s) - metrology , calibration , interferometry , surface (topology) , optics , surface metrology , mechanical engineering , morse code , optical instrument , dimensional metrology , finite element method , computer science , engineering drawing , physics , engineering , mathematics , geometry , structural engineering , profilometer , surface finish , telecommunications , quantum mechanics
The paper presents the effect of mechanical mounting of optical reference elements on their surface shape. Optical reference surfaces are key elements when traceable, highly accurate and precise optical surface measurements are required. In order to calibrate measuring instruments and compare the metrological capabilities of different metrology institutes, universities and other stakeholders, the reference artefacts were developed. Different measurement instruments require a different way of mounting and the reference artefacts are supposed to be useful for reliable and repeatable calibration of a great majority of the instruments worldwide. However, not only their shape was critical, but also the way of mounting was crucial. FEM analyses followed by experiments have revealed an unacceptable surface shape error in the order of hundreds of nanometres in the case of the commonly used screw mount, even for low applied torques. Other mounting options, such as the collet chuck or the Morse taper, are examined by means of FEM analysis and verified by interferometric measurements. It is shown that only the Morse taper can fulfil the strict criterion of less than 30 nm for surface shape deviation due to mounting, which is required in optical surface shape metrology.