Prime focus spectrograph (PFS) for the Subaru telescope: fiber optical cable and connector system (FOCCoS) – Integration

In this paper, we present the beginning of the last phase of the integration process of the FOCCoS subsystem, "Fiber Optical Cable and Connector System", to be installed on the Subaru telescope as part of the PFS (Prime Focus Spectrograph) project [01]. FOCCoS consists of the 3 cables (A, B and C) to integrate and operate the instruments easily [02]. At the present stage, we are about to complete the integration of the 3 cables by building Cable B that intermediates the telescope’s light gathering and light output devices for the spectrographs. Cable B, which is ~55m long, is subdivided into 4 units. Each unit has 600 optical fibers inserted into segmented tubes that are helically stranded around the tensile core element and inserted into a flexible metal conduit, which was made by industrial process. The construction of Cable B unit involves a coherent fiber distribution for a required mapping between the light collecting ends and the output ends positioned on the slits. Multi-fiber connector bench, strain relief boxes, and connection monitoring fiber devices are being built as part of subsystem integration process. Specific FRD measurement procedures for Cable B have been fully developed and implemented. The measurements are so far indicating similarly good results to those obtained in the evaluation of fibers from Cables A and C. For Cable B, FRD of some fibers has been traced to monitor the impact of the integration process.