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Production sequence of Si-spheres and interferometrical determination of the sphere volume

Interferometry on Material Measures

Department 5.4


The main tasks of the department comprise research and development for the realization and dissemination of the unit of length "meter":

  • Spherical interferometer:
    New determination of the Avogadro constant, traceability of the density

  • Precision interferometer:
    Length changes of technologically relevant materials with temperature

  • Diode laser interferometer:
    Multiwavelength diode laser interferometry, absolute interferometry, refractive-index-compensating interferometry

For this purpose, fundamental research is performed within the scope of projects of PTB, DFG and industry in order to develop and optimize measuring procedures, standards and measuring facilities with the best measurement capabilities.
In addition, calibrations of material measures (gauge blocks) and length measuring equipment (line scales, range finders, laser interferometers, measuring probes), the issuance of Type and design examination certificates of instruments designed to measure lengths and their combinations in accordance with Directive 2004/22/EC Annex MI-009 of the European Parliament, approval for verification of choirometers, round timber measuring systems and range finders.
Another important task is the consulting, assessment and training of DKD laboratories for gauge blocks.

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