Design and construction of the GNIRS IFU

Abstract The addition of an image slicing integral field unit (IFU) developed by the Centre for Advanced Instrumentation (CfAI) of Durham University, has given the Gemini near-infrared spectrograph (GNIRS) – currently in operation at the Gemini South telescope – a powerful capability for integral field spectroscopy (IFS). An innovative feature of this IFU is the use of monolithic multi-faceted mirror arrays which were fabricated using freeform diamond machining techniques. In this paper, we present a summary of the design, construction and measured performance of the GNIRS IFU. Details of the fabrication process of the optical components are also presented.