exit pupil

noun

, Optics.

1. the ridge of the entrance pupil of an optical system, indicating the place where the pupil of the eye should be placed to view the object.

exit pupil

noun

1. the smallest cross section of the beam of light from the eyepiece of a telescope through which all the light from the eyepiece passes. Its diameter is equal to the ratio of the focal length of the eyepiece to the focal ratio of the telescope

Example Sentences

The exit pupil then lies in the image-side focus of the system.

From Project Gutenberg