collimate : Idioms & Phrases
Collimating eyepiece
- an eyepiece with a diagonal reflector for illumination, used to determine the error of collimation in a transit instrument by observing the image of a cross wire reflected from mercury, and comparing its position in the field with that of the same wire seen directly.
Webster 1913
Collimating lens
(Optics) , a lens used for producing parallel rays of light.