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Asphere Metrology

Working Group 4.24

Profile

Aspherical optical elements (in short: aspheres), such as aspherical lenses, have surface forms that deviate from a spherical shape. This can reduce imaging errors and – at the same time – produce more compact optics. However, manufacturing these aspheres is complex, and currently, the achievable manufacturing accuracy is limited by the measurement accuracy of the surface form. There is therefore a great need for accurate measurement technology to determine the form of aspheres and to trace the measurements back to reference standards and reference devices.

The Asphere Metrology Working Group is developing a metrology system to measure the surface form of aspheres based on the optically operating tilted-wave interferometer. The aim is to implement a traceable measurement technique with a very low measurement uncertainty, so that current as well as future requirements can be met.

In addition, the Working Group is developing reference standards which can characterize and assess the performance of measuring systems.

Since the measuring principle of the tilted-wave interferometer also makes it possible to measure optical surfaces that no longer have rotational symmetry (so-called freeform surfaces), the Working Group is also active in this field.

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Research/Development

  • Development of a traceable metrology system for the form measurement of aspheres with very low measurement uncertainty based on the tilted-wave interferometer

  • Further development of the measuring system for the form measurement of freeform surfaces in cooperation with Working Groups 4.21 and 4.22

  • Development and testing of new numerical and statistical methods, such as the application and development of various machine learning methods, in cooperation with Working Group 8.42

  • Participation in and evaluation of measurement comparisons in the context of research projects and with the “Nanotechnologie Kompetenzzentrum Ultrapräzise Oberflächenbearbeitung” (CC UPOB e.V.)

  • Development of reference standards

  • Participation in the “Metrologie für virtuelle Messgeräte” (VirtMet) competence center

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