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We present the results of our project for the design and construction and on-sky test of silicon grisms. The fabrication of such devices is a complex and critical process involving litho-masking, anisotropic etching and direct bonding techniques. After the successful fabrication of the silicon grating, we have optimized the bonding of the grating onto the hypotenuse of a silicon prism to get the final prototype. After some critical phases during the experimentation a silicon grism with 363 grooves/mm and a blaze angle of 14 degrees has been eventually fabricated. The application of an A/R coating on both the surfaces has been the last step: this procedure is critical because of the groove geometry of the diffraction grating, whose performace might be compromised by the coating. Then, the grism was inserted in the filter wheel of the Near Infrared camera NICS, at the focal plane of the National Galileo Telescope (TNG), the 3 …
International Society for Optics and Photonics
Publication date: 
7 Aug 2014

Fabrizio Vitali, Vittorio Foglietti, Dario Lorenzetti, Elena Cianci, Francesca Ghinassi, Avet Harutyunyan, Simone Antoniucci, Carlos Riverol, Luis Riverol

Biblio References: 
Volume: 9151 Pages: 91515B
Advances in Optical and Mechanical Technologies for Telescopes and Instrumentation