EU project aims for optical surface accuracy below 1nm

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Measuring optical surfaces to an accuracy of less than 1nm for flats and some tens of nanometres for aspheres are two of the goals of a new €2.9 million three-year European Union project.

The researchers will aim to extend flatness metrology for reference surfaces down to the sub-nanometre range; improve lateral resolution below 100μm, even for large specimens; implement an optical asphere metrology system based on Tilted Wave Interferometry (TWI) and traceable stitching techniques; and improve single-point scanning techniques for asphere metrology.

‘Aspheres can be manufactured down to nanometre accuracy. But different optical or tactile inspection methods result in the measurement of different topologies. An assembly of national metrological institutes and industrial stake holders are now trying to resolve this discrepancy within this three year project,’ said Physikalisch-Technische Bundesanstalt’s (PTB) technology transfer commissioner, Dr Bernhard Smandek.

The expertise to conduct this project exists in Europe, but not in industry and not in any single national metrology institute. The project called 'optical and tactile metrology for absolute form characterisation', is expected to facilitate a ‘significant advancement in form metrology of optical surfaces’.

The organisations involved include, PTB, IBS Precision Engineering, the University of Stuttgart, Xpress Precision Engineering, the Fraunhofer Institute, TU Illmenau and TNO. The project is also open to new entrants.