4MOST: manufacture, assembly and test of the optical fiber system

The 4MOST instrument is a multi-object spectroscopic survey facility for the VISTA telescope at Paranal. The large multiplex gain for 4MOST is achieved by connecting over 2400 optical fibers from the telescope focal plane to three spectrographs. The final system features 812 fibers per spectrograph of around 25m in cable length. In addition, there are dedicated fiber cables for simultaneous calibration, for secondary guiding, and fiducial reference fibers for metrology. The fiber cable specifications, manufacture, assembly, and acceptance tests are described. Sub-system testing includes sparsely-populated fiber-slit-units, used for spectrograph alignment and performance verification and the fiber cable routing through the Cassegrain cable wrap.