28 July 2014 The fiber-fed preslit of GIANO at T.N.G.
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Giano is a Cryogenic Spectrograph located in T.N.G. (Spain) and commissioned in 2013. It works in the range 950-2500 nm with a resolving power of 50000. This instrument was designed and built for direct feeding from the telescope [2]. However, due to constraints imposed on the telescope interfacing during the pre-commissioning phase, it had to be positioned on the rotating building, far from the telescope focus. Therefore, a new interface to the telescope, based on IR-transmitting ZBLAN fibers with 85μm core, was developed. Originally designed to work directly at the f/11 nasmyth focus of the telescope, in 2011 it has decided to use a fiber to feed it. The beam from the telescope is focused on a double fiber boundle by a Preslit Optical Bench attached to the Nasmith A interface of the telescope. This Optical Bench contains the fiber feeding system and other important features as a guiding system, a fiber viewer, a fiber feed calibration lamp and a nodding facility between the two fibers. The use of two fibers allow us to have in the echellogram two spectrograms side by side in the same acquisition: one of the star and the other of the sky or simultaneously to have the star and a calibration lamp. Before entering the cryostat the light from the fiber is collected by a second Preslit Optical Bench attached directly to the Giano cryostat: on this bench the correct f-number to illuminate the cold stop is generated and on the same bench is placed an image slicer to increase the efficiency of the system.
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A. Tozzi, A. Tozzi, E. Oliva, E. Oliva, L. Origlia, L. Origlia, C. Baffa, C. Baffa, V. Biliotti, V. Biliotti, G. Falcini, G. Falcini, E. Giani, E. Giani, Marcella Iuzzolino, Marcella Iuzzolino, F. Massi, F. Massi, N. Sanna, N. Sanna, Salvo Scuderi, Salvo Scuderi, M. Sozzi, M. Sozzi, } "The fiber-fed preslit of GIANO at T.N.G.", Proc. SPIE 9147, Ground-based and Airborne Instrumentation for Astronomy V, 91479N (28 July 2014); doi: 10.1117/12.2054094; https://doi.org/10.1117/12.2054094


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