Assertion: eyepiece's coating | /r/HasProperty | put on its front surface
Facets:
Source sentences:
text: Using a mirror rather than lenses has some benefits; only one face of the objective needs to be optically figured (as opposed to both faces of each of the multiple lenses in a Refractor); and the light doesn't pass through the mirror (its reflective coating is put on its front surface), so the glass can be much poorer quality.