Assertion: eyepiece's surface | /r/HasProperty | polished
Facets:
value: in a mirror
type: LOCATION
value: perfectly
type: DEGREE
Source sentences:
text: In a lens the entire volume of material has to be free of imperfection and inhomogeneities, whereas in a mirror, only one surface has to be perfectly polished.
text: A Cheshire eyepiece contains no lenses or other polished optical surfaces.