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Flatness Metrology

Working Group 4.22


In this working group, procedures for highly accurate flatness measurements of plane optical surfaces are developed and applied for calibrations. Deflectometric and interferometric methods are used for this purpose. In addition, new techniques for the absolute measurement of optical wavefronts are developed and applied for the characterization of wavefront sensors like Shack-Hartmann sensors.

Within the framework of a new research cooperation agreement with the European X-Ray Free-Electron Laser Facility (XFEL, Hamburg), the measurement procedures are being further developed to measure also slightly curved mirrors with nanometer accuracy. In other research projects, new interferometric approaches (shearing methods and multi-aperture interferometry) are being studied for applications in high accuracy form measurement.

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  • Deflectometric flatness reference (DFR) measurement system
  • Extended shear angle difference (ESAD) system for flatness measurement
  • Traceable multi sensor (TMS) technique for the form measurement of curved optical surfaces
  • Wavefront metrology
  • Development of mathematical models of the measurement systems in close cooperation with PTB's Working Group Data Analysis and Measurement Uncertainty


Projects / collaborations

The working group cooperates with international partners from industry, universities, research institutes and metrology institutes:

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