An easily scalable Theta/Phi fiber positioner to reduce risks, lead times, and costs for multi-object spectrographs

This paper presents the design and performance of an easily scalable Theta/Phi fiber positioner for Multi-subject Spectrographs. It has been developed by Ecole Polytechnique Federale de Lausanne (EPFL) together with the Swiss manufacturer of miniature microsystems MPS Microsystems. The positioner has been designed with the purpose of adapting readily to the requirements of any Multi-Object Spectrograph, which requires precise positioning of optical fibers. Whether MOONS, COBRA, MEGARA, or DESI, each project has so far developed its own fiber positioner from scratch, with all of the risks linked to such a complete new development. The positioner presented in the current paper intends to significantly reduce the development time, costs, and eliminate unforeseen risks. The design is easily scalable in size, length, and shape. For validation, we built eight prototypes with a diameter of 9.5mm which are capable to reach any target within five micrometers with just two correction moves.