Bibcode
Fragoso-Lopez, Ana B.; Manescau, Antonio; Garzon, Francisco; Patron, Jesus
Bibliographical reference
Specialized Optical Developments in Astronomy. Edited by Atad-Ettedgui, Eli; D'Odorico, Sandro. Proceedings of the SPIE, Volume 4842, pp. 282-292 (2003).
Advertised on:
2
2003
Citations
1
Refereed citations
0
Description
EMIR is a multiobject intermediate resolution (R ≍ 4000) near
infrared spectrograph with image capabilities to be mounted on the Gran
Telescopio Canarias (GTC). EMIR shall provide image and spectra of a
wide FOV (6x6 arcmin in imaging mode and 6x4 arcmin in multiobject
spectroscopic mode), and will use grisms as dispersive elements. The use
of grisms has great advantages in the design and manufacture of infrared
spectrographs but there are not many suitable materials for the EMIR
requirements. The grisms material must have good transmission in the
working spectral range (1.0 - 2.5 μm) and given the required
resolution, a high refractive index is necessary. Also the required
homogeneity of the grism material makes it difficult to find a good
candidate due to the large size of the EMIR grisms. Furthermore the
technical difficulties related to the grooving process on large surfaces
is an important issue to be addressed. Taking into account all those
constraints and the EMIR requirements, several sets of materials,
rulings and dimensions have been identified. These alternative solutions
for EMIR grisms are proposed and analysed in terms of their physical
characteristics, expected resolution, spectral coverage on detector and
diffraction efficiency. Current status of the procurement of the devices
will be given.