Assertion: cassegrain reflector | /r/HasAspect | hole
Facets:
Source sentences:
text: There are many types of reflectors that solve the issue of where to focus the light in different ways such as Cassegrain reflectors which have a convex secondary mirror and a hole in the middle of the primary mirror.
text: Cassegrain reflectors have a convex secondary mirror and a hole in the middle of the primary mirror.