Miniature optical fiber positioner developed specifically for the Dark Energy Spectroscopic Instrument (DESI)

DESI optical fiber positioner

As part of a European consortium, MPS Microsystems participated in the competition to design a miniature optical fiber positioner organised by the Berkeley University in California. Known as DESI, 'Dark Energy Spectroscopic Instrument', this positioner has an outside diameter of 10 mm and offers positioning accuracy for the fiber of less than 5 µm in the X-Y plane. MPS Microsystems contributed its expertise in manufacturing miniature electromechanical systems and produced 6 functional prototypes, which were tested successfully.

The positioner comprises two independently rotating parallel axes driven by two FAULHABER brushless motors 4 mm in diameter, each fitted with a rotary encoder and a reduction gearhead. Rotation of the Alpha and Beta arms is limited to avoid excessive curvature of the optical fiber.



    Diameter: 10 mm
    Diameter covered by the fiber: 12 mm
    Total length: 165 mm
    Length (from the focal plane): 95 mm
    Motor drive: 2 x BLDC0420 with 128 encoder and 1024:1 reduction gearhead
    X-Y positioning accuracy: < 5 µm
    Inclination of the fiber relative to the X-Y plane: < 0.1°
    Alpha arm rotation: 365°
    Beta arm rotation: 180°


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