Current status of the HETDEX fiber optic support system

John M. Good, Gary J. Hill, Nicholas T. Mollison, Brian L. Vattiat, Jeremy D. Murphy, Andreas Klez, Martin M. Roth, Phillip J. MacQueen, Marc D. Rafal, Richard D. Savage, Michael P. Smith, Amanda J. Bayless (+2 others)
2008 Ground-based and Airborne Instrumentation for Astronomy II  
The Hobby-Eberly Telescope Dark Energy eXperiment [HETDEX] will employ over 43,000 optical fibers to feed light to 192 Visible Integral-Field Replicable Unit Spectrographs [VIRUS]. Each VIRUS instrument is fed by 224 fibers. To reduce cost, the spectrographs are combined into pairs; thus, two bundles of 224 fibers are combined into a single Integral Field Unit [IFU] of 448 fibers. On the input end the fibers are arranged in a square 'dense-pack' array at the HET focal surface. At the output end
more » ... . At the output end the IFU terminates in two separate linear arrays which provide entry slits for each spectrometer unit. The IFU lengths must be kept to an absolute minimum to mitigate losses; however, consideration of overall project cost and duration of the science mission have resulted in the generation of two competing concepts. Multiple axes of motion are imposed on the IFUs as they span the shortest distance from the focal surface to each VIRUS unit. Arranging 96 IFUs in a manner that is compatible with these complex translations, together with the management of accompanying forces presents a significant technical challenge, which is further compounded by wind buffeting. The longer IFU concept is favored due to cost, but requires tests to assure that the fibers can withstand forces associated with a height differential of 16.25 meters without FRD losses or breakage.
doi:10.1117/12.790256 fatcat:nknb5xw3fjfknmei6mgy5cwza4