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The Collimator

The collimator located at the bottom of the spectrograph is a 3.5 inch diameter, f/9 off-axis parabolic mirror. Because the beam at this point is only 3.0 inches in diameter, the beam is unvignetted by this element over the nearly 1-inch (240) length of the spectrograph slit.

Pat Hall - Wed Oct 4 11:02:37 MST 1995