Prime Focus Spectrograph (PFS) Fiber Positioner Testbed Development
- David Braun, Group Supervisor, Jet Propulsion Laboratory, California Institute of Technology
- Charlie Fisher, Positioner Cognizant Engineer, Jet Propulsion Laboratory, California Institute of Technology
- Joel Kaluzny, Opto-Mechanical Engineer, Jet Propulsion Laboratory, California Institute of Technology
Spectroscopic observation of cosmological targets allows galactic archaeology studies and dark energy surveys, which help us understand large-scale structures in the universe. Current multi-object spectroscopy technologies can observe only a small number of targets simultaneously, thus offering limited scientific utility. A new instrument is needed to conduct wide field surveys. The Prime Focus Spectrograph (PFS) is being developed for this purpose, and will be an instrument of the Subaru Telescope on Mauna Kea, Hawaii. This instrument includes an array of 2400 optical fibers, arranged in a close-packed hexagonal layout and positioned by Cobra rotary mechanisms. Each fiber can collect light from a distinct target, allowing simultaneous analysis of many cosmological objects. An improved Cobra fiber positioner was developed this summer, and the positioner testbed was upgraded to allow for multi-positioner testing. NX was used for mechanical design of testbed components, and MATLAB was used to develop the motor control and collision-avoidance algorithms. This will allow implementation of collision-avoidance algorithms, as well as positioner characterization and improvement studies. Tests performed with the new setup will assess positioner performance, help finalize positioner design, improve projections for full-scale target reconfiguration times, and be used to develop software and discover issues for final instrument design and assembly.