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New dichroic and blue mirror folder
A new dichroic and mirror for the blue folder has just been aquired
and tested. Both are much better than the old ones. This dichroic unit
is planned to be the default one starting semester 2005B. Those
interested in using it instead of the dichroic asked in the proposal
already approved should contact Javier Licandro (licandro@ing.iac.es).
The response of the new dichroic was measured on the spectrograph as
it was done in the case of the old ones.
The result is shown in the following Figure.
Notice that compared with the old ones
the
throughput is better (>95% in the red arm, and also in the blue
according to the predictions) . Also the ripples, in particular in the
blue arm, are much less important than those of the old ones.
The Cross-over Point is at ~5336 Angs. The cut-off region is also
smaller than that of the old dichroics, the througput in both arms is
below 70% in the 5200-5400 Angs. region. The dichroic reflectance is
~4%
better than that of the mirror in the 3500-5100 Angs region.
The througput of the mirror is larger than 95% according to the
provider. The relative throughput of the new mirror respect to that
installed in the same unit of the old 5400 dichroic is shown in the
next
figure. Notice that the throughput of the new one is >10%
better in the blue.
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Last Updated: January 2005
Javier Licandro licandro@ing.iac.es
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