Fiber optical cable and connector system (FOCCoS) for PFS/ Subaru

Abstract

FOCCoS, "Fiber Optical Cable and Connector System" has the main function of capturing the direct light from the focal plane of Subaru Telescope using optical fibers, each one with a microlens in its tip, and conducting this light through a route containing connectors to a set of four spectrographs. The optical fiber cable is divided in 3 different segments called Cable A, Cable B and Cable C. Multi-fibers connectors assure precise connection among all optical fibers of the segments, providing flexibility fo r instrument changes. To assure strong and accurate connection, these sets are arranged inside two types of assemblies: the Tower Connector, for connection between Cable C and Cable B ; and the Gang Connector, for connection between Cable B and Cable A. Throughput tests were made to evaluate the efficiency of the connecti ons. A lifetime test connection is in progress. Cable C is installed inside the PFI, Prime Focus Instrument, where each fiber tip with a microlens is bonded to the end of the shaft of a 2-stage piezo-electric rotatory motor positioner; this assembly allows each fiber to be placed anywhere within its patrol region, which is 9.5mm diameter. . Each positioner uses a fiber arm to support the ferrule, the microlens , and the optical fiber. 2400 of these assemblies are arranged on a motor bench plate in a hexagonal-closed-packed disposition. All optical fibers from Cable C, protected by tubes, pass through the motors' bench plate, three modular plates and a strain relief box, terminating at the Tower Connector. Cable B is permanently installed at Subaru Telescope structure, as a link between Cable C and Cable A. This cable B starts at the Tower Connector device, placed on a lateral structure of the telescope, and terminates at the Gang Connector device. Cable B will be routed to minimize the compression, torsion and bending caused by the cable weight and telescope motion. In the spectrograph room, Cable A starts at the Gang Connector, crosses a distribution box and terminates in a slit device. Each slit device receives approximately 600 optical fibers, linearly arrayed in a curve for better orientation of the light to the spectrograph collimator mirror. Four sets of Gang Connectors, distribution boxes and Slit devices complete one Cable A. This paper will review the general design of the FOCCoS subsystem, methods used to manufacture the involved devices, and the needed tests results to evaluate the total efficiency of the set.

Prime Focus Spectrograph (PFS) for the Subaru telescope: ongoing integration and future plans

“…Fiber system "FOCCoS" to be delivered by LNA [15][16][17][18] consists of three parts: Two short-fiber systems accommodated in PFI and SpS, and a long cable system that is routed on the telescope to connect PFI and SpS. These three parts are connected together by two sets of fiber connectors.…”

Prime Focus Spectrograph (PFS) for the Subaru Telescope: Overview, recent progress, and future perspectives

“…Fiber system "FOCCoS" to be delivered by LNA 24 consists of three parts: Two short-fiber systems accommodated in PFI and SpS, and a long cable system between them routed on the telescope. The route of this long one is still being finalized, but the total fiber length will be approximately 65m.…”

Progress with the Prime Focus Spectrograph for the Subaru Telescope: a massively multiplexed optical and near-infrared fiber spectrograph

“…It consists of two components: the prime focus part and the spectrograph part, with the fiber system connecting the two parts. In this conference we have eighteen papers on the PFS instrumentation: instrument overview (the present paper), fiber system 3,4,5,6,7,8 , fiber positioner 9 & Prime Focus Instrument 10 , spectrograph 11,12,13 , dewar & detector 14,15,16,17,18 , and metrology camera 19 . In the present paper the instrument overview is provided.…”