Spectrometer Specifications | |||||||||||||||||||||||||||||
The Instrument uses a fixed width slit, three prisms to cross disperse the light into at least 5 orders across the science detector, and a mid resolution grating. In addition, the first fold mirror is mounted on a piezo tip-tilt stage (S-340) to minimize the effects of flexure (FCS). Spectrograph schematics from Wilson et al. 2004
3D representation showing the tip-tilt mirror. SlitThe instrument has a fixed slit of 0.55" width and 18" in length. It is made of a reflective material. In early 2018 we detected an imperfection in the slit. The effect of this imperfection is to show a trace on the dome flats. The follwing drawing (all dimensions are in units of arcseconds) shows the position of the imperfection (shown as a triangle). If possible, we suggest to avoid the compromised section of the slit.
PrismsTwo first two prisms are made of ZnSe with a 22 degree apex. The third prism is made of Infrasil with 50 degrees apex. Grating
Spectral resolution as a function of wavelength and order for a 0.55 arcsec slit. Final SpectrumThe dispersed light is focused by a 7-element camera onto the detector. The following is a 700 seconds exposure obtained at CIT. The spectrum shows five cross-dispersed orders that almost (small gap from 1.85 to 1.88 microns) continously cover the near-IR spectrum from the Y band (order 7 at the bottom) to the K band (order 3 at the top).
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Last modified: 09/20/2018 08:05 Send questions or comments to:NIRES Support |