Alignment methods for ultraprecise deflectometric flatness metrology

Gerd Ehret; Michael Schulz; Arne Fitzenreiter; Maik Baier; Wolfgang Jöckel; Manuel Stavridis; Clemens Elster

doi:10.1117/12.889325

26 May 2011 Alignment methods for ultraprecise deflectometric flatness metrology

Gerd Ehret, Michael Schulz, Arne Fitzenreiter, Maik Baier, Wolfgang Jöckel, Manuel Stavridis, Clemens Elster

Proceedings Volume 8082, Optical Measurement Systems for Industrial Inspection VII; 808213 (2011) https://doi.org/10.1117/12.889325
Event: SPIE Optical Metrology, 2011, Munich, Germany

Abstract

At the Physikalisch-Technische Bundesanstalt (PTB) two new scanning deflectometric systems (Deflectometric Flatness Reference: DFR) were installed for measuring topographies of nearly flat surfaces with sub-nanometre uncertainty. The two systems can measure the form of horizontally and vertically orientated specimens with a diameter of up to 700 mm. The systems are based on different deflectometric procedures, the so-called direct and the difference deflectometry. With the flatness measuring systems, an uncertainty down to 0.1 nm (depending on the specimen and its peak-to-valley) is being aimed at for the 95% coverage interval. Virtual experiments show that the optical and mechanical components must be aligned in the arcsecond range in order to achieve errors for the topography in the sub-nanometre range. In this paper we describe the setup of the new DFR system for horizontally orientated specimens in detail and show methods and experimental results for an accurate alignment of the optical and mechanical components. We present an accurate alignment strategy for ultraprecise deflectometric measurements and show a measurement of a section at a horizontally orientated specimen.

Citation Download Citation

Gerd Ehret, Michael Schulz, Arne Fitzenreiter, Maik Baier, Wolfgang Jöckel, Manuel Stavridis, and Clemens Elster "Alignment methods for ultraprecise deflectometric flatness metrology", Proc. SPIE 8082, Optical Measurement Systems for Industrial Inspection VII, 808213 (26 May 2011); https://doi.org/10.1117/12.889325

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