CONCEPTUAL DESIGN AND STUDY OF HIGH-PRECISION TRANSLATIONAL STAGES - APPLICATION TO AN OPTICAL DELAY-LINE

This paper describes some aspects of the design approach and modeling of an optical delay line for the east-west stellar interferometer of t he Observatoire de la Cote d'Azur (OCA) in France. The optical delay l ine with a long stroke of 3 m, has been designed with two stages. An u pper stage is supported by aerostatic porous media bearings on a lower stage that travels on rollers. Interstage decoupling has been matched to achieve the required stability for the high-precision upper stage. Guidelines with theoretical analysis and experimental results are pre sented. A theoretical model for the assembled system has been develope d, taking into account the rolling contact and the disturbances induce d by microasperities on the tracks. The natural frequencies have been determined with the bearings characteristics necessary to meet require ment specifications. Experimental results show good agreement with the requirements. Moreover, analytic modeling and finite element modeling (FEM) analysis seem to be good tools for predicting movement at the n anometer level, even with high loads and long strokes. (C) 1997 Elsevi er Science Inc.