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Flatness Metrology

Working Group 4.22


Our working group provides and enhances optical systems for highly accurate flatness measurements of plane surfaces in order to carry out tasks such as highly accurate calibrations for customers. These systems are based on deflectometric and interferometric methods. To cover the needs for measurements of larger plane surfaces (with diameters up to 1.5 m), a new measurement system is currently being set up. It will be possible to use this measurement system for measuring not only plane surfaces, but also slightly curved freeform surfaces.

Within the scope of a research cooperation project with the European X-Ray Free-Electron Laser Facility (XFEL, Hamburg), measurement procedures for measuring the form of slightly curved mirrors with nanometer accuracy are being developed and implemented, and comparison measurements are being carried out. In research projects (e.g. with partners from universities), novel interferometric approaches (shearing procedure and multiple aperture interferometry) are being investigated as to their suitability for high-accuracy form measurement.

Two PTB measurement systems are currently taking part in an international interlaboratory comparison for the high-accuracy optical flatness measurement of plane surfaces with a diameter of 300 mm.

In addition, procedures for the absolute measurement of optical wavefronts are being developed and used to characterize wavefront sensors (e.g. Shack-Hartmann wavefront sensors).

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Projects/Cooperation projects

Our working group cooperates with national and international partners from industry, universities, research institutions as well as metrology institutes.

Abgeschlossene Projekte

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