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VLT-MAN-ESO-14650-4942
P96
24.06.2015
35 of 161
ESO, Karl-Schwarzschild-Str. 2, 85748 Garching bei München, Germany
2.2.3 Detector QE curves
2.2.4 The UVB spectrograph
2.2.4.1 Slit carriage
The first opto-mechanical element of the spectrograph is the slit carriage. Besides the slit
selection mechanism, this unit consists of a field lens placed just in front of the slit to re-
image the telescope pupil onto the spectrograph grating, and the spectrograph shutter just
after the slit. The slit mask is a laser cut Invar plate manufactured with the LPKF Laser Cutter
used for FORS and VIMOS. It is mounted on a motorized slide in order to select one of the 9
positions available. All science observation slits are 11” high and different widths from 0.5” to
5” (the latter for spectro-photometric calibration) are offered. In addition a single pinhole for
spectral format check and order tracing and a 9-pinhole mask for wavelength calibration and
spatial scale mapping are available (see Table 4).
Table 4: UVB spectrograph slits and calibration masks
Size
Purpose
0.5”
11” slit
SCI / CAL
0.8”
11” slit
SCI / CAL
1.0”
11” slit
SCI / CAL
1.3”
11” slit
SCI / CAL
1.6”
11” slit
SCI / CAL
5.0”
11” slit
CAL
Row of 9 pinholes of 0.5”
spaced at 1.4”
CAL
0.5”
pinhole
CAL