Assertion: telescope's mirror | /r/CapableOf | permit the light
Facets:
value: to reach an eyepiece
type: PURPOSE
value: to reach a camera
type: PURPOSE
Source sentences:
text: In a symmetrical Cassegrain both mirrors are aligned about the optical axis, and the primary mirror usually contains a hole in the centre, thus permitting the light to reach an eyepiece, a camera, or an image sensor.