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 the Observatoire de la Côte d'Azur (OCA) in France. The optical delay line with a long stroke of 3 m, has been designed with two stages. An upper 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 presented. A theoretical model for the assembled system has been developed, taking into account the rolling contact and the disturbances induced by microasperities on the tracks. The natural frequencies have been determined with the bearings characteristics necessary to meet requirement 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 nanometer level, even with high loads and long strokes.