noun : COLLIMATOR
Source: WordNet 3.1
-
1. (
) a small telescope attached to a large telescope to use in setting the line of the larger one ;
-
2. (
) optical device consisting of a tube containing a convex achromatic lens at one end and a slit at the other with the slit at the focus of the lens; light rays leave the slit as a parallel beam ;
See more about : COLLIMATOR