An ultraprecision fiber connector for FMOS

摘要

A fibre-fed near IR (J & H band) multi-object spectrograph (FMOS) is being constructed by a consortium of UK, Australian and Japanese groups for the SUBARU telescope on Mauna Kea, Hawaii. The prime focus of the telescope will support ECHIDNA, a 400-fibre multi-object positioning system. However, the IR spectrographs are located close to the Nasmyth platform, so an optical feed is required to deliver light from ECHIDNA to the spectrographs. The Astronomical Instrumentation Group at the University of Durham is undertaking the design and construction of a suitable fibre-optic downlink. To allow the prime focus unit that houses ECHIDNA to be removed, the fibre cabling is to include a connectorised break. The optical design of the fibre system also calls for a change in focal ratio from that delivered by ECHIDNA in order to couple light to the spectrographs with the greatest efficiency. This will be achieved in a custom designed connector head by means of a tailored lens array. The connector design will in addition incorporate a back-illumination system for fibre position determination at the prime focus. This paper describes the overall design of the connector that is to be employed. The modularity of the scheme and various innovative features are highlighted. A more advanced connector concept capable of dual bandwidth (visible & NIR) operation is also shown. Such a system could significantly enhance the science return from future ECHIDNA-type fibre instruments.