The Dark Energy Spectroscopic Instrument (DESI) is under construction to determine the expansion history of the Universe using the Baryon Acoustic Oscillation technique. Over the life of the experiment DESI will measure the spectra of 35 million galaxies and quasars over 14,000 square degrees out to a redshift of 3.5. A new prime focus corrector for the KPNO Mayall telescope will deliver light to 5,000 robotic fiber positioners located at the prime focus. The fibers in turn will feed ten broad-band spectrographs covering the wavelength range from 360nm to 980 nm. Rapid and accurate targeting of the fibers is provided by precision theta-phi robotic fiber positioners. The fiber positioners are manufactured at the University of Michigan. Following assembly each positioner passes through a burn-in and verification sequence. We describe the testing of the positioners and discuss the performance achieved.

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Michael Schubnell, Jessica Aguilar , Jon Ameel, Stefane Caseiro, Kevin Fanning, Brandon Freudenstein, Irena Gershkovich, Henry Heetderks, Philipp Hörler, Daniela Leitner, Michael Levi, Joseph Silber, Zhiquan Sun, Gregory Tarlé, Curtis Weaverdyck, Kai Zhang, and David Brooks, "DESI fiber positioner testing and performance (Conference Presentation)," Proc. SPIE 10706, Advances in Optical and Mechanical Technologies for Telescopes and Instrumentation III, 107062A (Presented at SPIE Astronomical Telescopes + Instrumentation: June 15, 2018; Published: 10 July 2018); https://doi.org/10.1117/12.2311573.5807230655001.