Multiple Aperture Shear-Interferometry (MArS): a solution to the aperture problem for the form measurement of aspheric surfaces

Multiple Aperture Shear-Interferometry (MArS) is a shape measurement technique that uses multi-spot illumination to overcome the problem of a limited observation aperture of conventional interferometric techniques and thus considerably simplifies the measurement of optical aspheres and freeform surfaces. Using a shear interferometry setup, MArS measures the coherence function in order to obtain wave vector distributions created from multi-spot LED illumination reflected by the specimen. Based on the wave vectors we reconstruct the surface topography of aspheric lenses using an inverse ray tracing approach and prior knowledge about the individual source locations. We present the topographic measurement of two aspheric lenses with different global curvature radii measured with the same identical reflection setup. In addition, we examine the achievable accuracy of the wave vector measurement using a single light source to find physical limits of MArS.

Authors:
André F. Müller: BIAS - Bremer Institut für angewandte Strahltechnik GmbH,Germany
Claas Falldorf: BIAS - Bremer Institut für angewandte Strahltechnik GmbH,Germany
Marcel Lotzgeselle: 4.2 Imaging and Wave Optics, PTB-Braunschweig
Gerd Ehret: 4.2 Imaging and Wave Optics, PTB-Braunschweig
Ralf B. Bergmann: BIAS - Bremer Institut für angewandte Strahltechnik GmbH,Germany, University of Bremen, Germany

For further information:
Optics Express Vol. 28, Issue 23, pp. 34677-34691 (2020), https://doi.org/10.1364/OE.408979

Contact person:
Dr. Gerd Ehret