Having made prototypes of the DESI positioner and produced 120 positioners for the Gran Canaria Large Telescope – GTC, MPS Microsystems was instructed by the consortium for the MOONS programme – Multi Object Optical and Near-infrared Spectrograph – to develop and produce 1,100 optical fiber positioners to be fitted on the VLT – Very Large Telescope – in Chile.

With an outside diameter of 25 mm, the positioners consist of 2 parallel axes driven by FAULHABER stepper motors of 8 mm in diameter. Zero backlash reduction gearheads guarantee X-Y positioning accuracy of less than 20 µm. Here, the optical fiber doesn't pass through the device but runs along it, unlike for other MPS Microsystems positioners. One of the major technical challenges of this project is to limit the lateral deviation of positioners to less than 0.25° although they are fixed to the focal plane by the base and are 210 mm long.