X-shooter
User Manual
Doc:
Issue
Date
Page
VLT-MAN-ESO-12000-0115
1
01.03.2009
20 of 60
ESO, Karl-Schwarzschild-Str. 2, 85748 Garching bei München, Germany
Slit wheel
A circular laser cut Invar slit mask is pressed in between two stainless steel disks with 12
openings forming the wheel. The wheel is positioned by indents on the circumference of the
wheel with a roll clicking into the indents. All the science observation slits are 11” high and
different widths are offered from 0.4” to 5” (see Table 8).
Table 8: NIR spectrograph slits and calibration masks
Size
Purpose
0.4”
×
11” slit
SCI / CAL
0.6”
×
11” slit
SCI / CAL
0.9”
×
11” slit
SCI / CAL
1.2”
×
11” slit
SCI / CAL
1.5”
×
11” slit
SCI/CAL
5.0”
×
11” slit
CAL
Raw of 9 pinholes of 0.5”
∅
spaced at 1.4”
CAL
0.5”
∅
pinhole
CAL
Optical layout
The optical layout of the NIR spectrograph is presented in Figure 7. The conceptual design is
the same than for the UVB and the VIS spectrographs. Light entering the spectrograph via
the entrance slit and folding mirror M5 feeds an off-axis Maksutov-inspired collimator. In this
case, the collimator is made of 2 spherical mirrors M6 and M7 plus an Infrasil corrector lens
(with only spherical surfaces). In order to get enough cross dispersion, three prisms are used
Figure 7: The NIR spectrograph optical layout.
