Assertion: telescope's mirror | /r/HasProperty | supported
Facets:
value: from the back
type: OTHER
value: opposite its reflecting face
type: OTHER
Source sentences:
text: Third, the objectives can be made very large, since there is only one optical surface to be polished to high tolerance, the optical quality of the mirror substrate is unimportant and the mirror can be supported from the back to prevent bending.
text: A mirror, on the other hand, can be supported by the whole side opposite to its reflecting face.
text: A mirror can be supported from the back, so it is less subject to sagging.
text: In contrast, a mirror can be supported by the whole side opposite its reflecting face, allowing for reflecting telescope designs that can overcome gravitational sag.