Updated on June 9, 2021, 8:28 am
The collimator mirror is an off-axis (11°) paraboloid of 225mm diameter and 1161mm focal length. The point-source beam size is 152mm.
There are two collmators available for the R-C spectrograph on the Blanco 4-m, the "blue" collimator and the "red" collimator. The difference is that the blue collimator is Aluminium coated, while the red is silver coated.
NOTE: As of 20 Apr 2000, the red collimator is not available because the coating was damaged. We are investigating recoating it, but in the mean time, only the blue collimator is available.
The plot below shows the last measured reflectivities of the two collimators.
Just for reference, the following plot and table show the catalog reflectivities for Ag and Al over the optical spectral range. This shows the theoretical best performance of the two coatings, NOT the real values.
Last update: April 24, 2000