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Proceedings Paper

New GRISMs for AFOSC based on volume phase holographic gratings in photopolymers
Author(s): Alessio Zanutta; Andrea Bianco; Marco Landoni; Lina Tomasella; Stefano Benetti; Enrico Giro
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Paper Abstract

Volume Phase Holographic Gratings (VPHG) can provide an improvement of diffraction efficiency and function- ality in already available astronomical instrumentation. Here, we present the design, manufacturing and testing of two GRISMs mounted on the AFOSC camera (at the 1.8 m Asiago telescope) based on VPHGs. Such diffrac- tion gratings have been written on a new solid and green sensitive photopolymer material produced by Bayer MaterialScience AG that show interesting performances (refractive index modulation, homogeneity, stability). The GRISMs have been designed according to the specific requests of astronomers. One GRISM consists in a very low dispersion VPHG (285 l/mm) that covers the range 500 - 1000 nm and suitable for observations of supernovae. The second one is a 600 l/mm VPHG for the Ha region. Both gratings show peak efficiency close to 90% and same diffraction efficiency is shown by the corresponding GRISMs. This high device’s performances means that the coupling losses are very low, also thanks to the matching of the refractive index between sub- strates and prisms. Some observations have been finally carried out and the gain in terms of efficiency and signal to noise ratio have been calculated in order to compare the photopolymeric VPHGs with the classic GRISMs already mounted and used in the AFOSC spectrometer.

Paper Details

Date Published: 8 July 2014
PDF: 7 pages
Proc. SPIE 9147, Ground-based and Airborne Instrumentation for Astronomy V, 91474E (8 July 2014); doi: 10.1117/12.2055775
Show Author Affiliations
Alessio Zanutta, Politecnico di Milano (Italy)
INAF - Osservatorio Astronomico di Brera (Italy)
Andrea Bianco, INAF - Osservatorio Astronomico di Brera (Italy)
Marco Landoni, INAF - Osservatorio Astronomico di Brera (Italy)
Lina Tomasella, INAF - Osservatorio Astronomico di Padova (Italy)
Stefano Benetti, INAF - Osservatorio Astronomico di Padova (Italy)
Enrico Giro, INAF - Osservatorio Astronomico di Padova (Italy)

Published in SPIE Proceedings Vol. 9147:
Ground-based and Airborne Instrumentation for Astronomy V
Suzanne K. Ramsay; Ian S. McLean; Hideki Takami, Editor(s)

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