Coudé Collimators

Two collimators are available, the "short" one and the "long" one. The long collimator is used only with gratings A and B, which are big enough to accommodate a 12" beam diameter. Gratings C, D, the echelle, and the RC gratings are only 8" wide, and must be used with the smaller collimator.

	    Table 2: Coude Spectrograph Collimators
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       f/ratio | focal length | pt. source | gratings
	       |      (m)     |   dia (mm) |
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small |  31.2  |      6.86    |    221.0   | C,D,echelle,RC
 col  |        |              |            |
large |  31.2  |     10.11    |    325.1   | A,B
 col  |        |              |            |
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