This mirror reflects the light of the object you're looking at up to the smaller, secondary mirror, which is located at the front of the tube.
(This mirror; reflects; the light of the object) (you; 're looking; at up to the smaller, secondary mirror) (the smaller, secondary mirror; is located; L:at the front of the tube)
This mirror you the smaller, secondary mirror
reflects 're looking is located
the light of the object
at up to the smaller, secondary mirror
L:at the front of the tube