Proposed extension of double-ended gauge block interferometers for measuring spheres

Abstract

Double-ended gauge block interferometers (DEI) are becoming more and more established. This paper suggests its extension for enabling interferometric measurement of diameter topographies of spheres as an alternative to the existing spherical Fizeau interferometers. The extension essentially consists in the addition of two lenses which are as similar as possible, which are arranged symmetrically around the sphere to be measured. The determination of the diameter topography from the interferometric measurements with inserted and without sphere in the extended DEI is derived and specific aspects are discussed. An adjustment strategy for the extended DEI is also suggested. In conclusion, the proposed extension appears to be a promising measurement tool, especially for measuring small spheres, as required for applications in coordinate metrology.

Special issue on metrology in manufacturing—Editorial

“…In the realised instrument, the deviation of the apex angle of the prism of interest from that of the reference prism is determined by measuring the prism faces of both the target prism and the reference prism by the corresponding optical angle sensors. The extension of an existing double-ended gauge block interferometer for the measurement of spheres is described by Schödel and Fischedick [13]. Based on the explanation of the instrument design of the double-ended gauge block interferometer, the concept for the modification of the interferometer beam path is described in detail and first measurement results are shown to proof the feasibility of the proposed extension for the measurement of spheres.…”