collimator

/ˌkɑləˈmeɪdər/

Other forms: collimators

Definitions of collimator

1. noun

   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
   type of:

   optical device

   a device for producing or controlling light
2. noun

   a small telescope attached to a large telescope to use in setting the line of the larger one
   type of:

   scope, telescope

   a magnifier of images of distant objects