Metrological needs and reliable solutions for optics fabrication related to E-ELT .

In order to contribute and support the R&D activities related to the E-ELT (European Extremely Large Telescope) program, the INAF-OAB acquired a dedicated robotic polisher machine, the IRP1200 by Zeeko. It will be used in synergy with the ion beam figuring technique, already available at OAB for the realization of prototypes and advanced optical components, as the optics of the Multi-conjugate Adaptive Optics Relay module (MAORY). In this paper, starting from the discussion of the metrological needs to be fulfilled during the different parts of the machining for the different kind of optics, we define the metrological scheme that will be followed. Moreover, we present the concept for a new measurement machine based of non-contact scanning probes, capable of nanometer uncertainty and compatible with the optics design to be realized. škip 0.5cm