The NANOMEFOS non-contact measurement machine for freeform optics

Aspherical and freeform optics are applied to reduce geometrical aberrations as well as to reduce the required number of components, the size and the weight of the system. To measure these optical components with nanometre level uncertainty is a challenge. The NANOMEFOS machine was developed to provide suitable metrology (high accuracy, universal, non-contact, large measurement volume and short measurement time) for use during manufacturing of these surfaces. This paper describes the design, realization and testing of this machine. In particular it describes the design and testing of the air-bearing motion system with parallel stage configuration, and the separate metrology system with Silicon Carbide metrology frame and an interferometry system for direct displacement measurement of the optical probe. Preliminary validation measurements demonstrate the nanometer level repeatability for freeform surface measurement.