30 June 2016 Interferometric measurement of highly accurate flat surfaces
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Proceedings Volume 10009, Third European Seminar on Precision Optics Manufacturing; 100090X (2016) https://doi.org/10.1117/12.2235525
Event: Third European Seminar on Precision Optics Manufacturing, 2016, Teisnach, Germany
The most important part in manufacturing precision optics is a reliable measurement procedure which provides results a few times more accurate than the quality to be produced. In general two specific values are important, the repeatability of several measurements which are done in a row and the absolute accuracy which is mostly defined by the systematical error of the measurement device. The repeatability can be improved relatively simple, by increasing the number of measurements and a following averaging step. To increase the absolute accuracy of a measurement device in the field of precision optics is far more challenging.

In this paper several interferometer absolute testing methods to measure flat surfaces are compared. The main objective was to name a value for the achievable accuracy. Therefor four different methods were analyzed:
    1. The three flat test, a method which is already used several decades to determine the quality of a flat surface. As a result, two absolute measured profiles, horizontal and vertical, can be calculated.
    2. The multi rotation test, an extension of the classical three flat test. The big advantage of this method is a fully three dimensional map of the systematical error.
    3. The systematical error calculated by the SSI-A. Hereby several subapertures are measured over the whole surface. The redundant information’s of the overlapping regions can be used to calculate the systematical error of the system.
    4. The rotation of the transmission flat relatively to the interferometer. Thereby the rotation unsymmetrical errors can be calculated and subtracted.
© (2016) COPYRIGHT Society of Photo-Optical Instrumentation Engineers (SPIE). Downloading of the abstract is permitted for personal use only.
J. Liebl, J. Liebl, H. Linthe, H. Linthe, S. Sitzberger, S. Sitzberger, R. Rascher, R. Rascher, "Interferometric measurement of highly accurate flat surfaces", Proc. SPIE 10009, Third European Seminar on Precision Optics Manufacturing, 100090X (30 June 2016); doi: 10.1117/12.2235525; https://doi.org/10.1117/12.2235525


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