Assertion: optical filter | /r/Desires | defined transmission curves
Facets:
value: precisely
type: MANNER
value: in practice
type: TEMPORAL
value: often
type: TEMPORAL
Source sentences:
text: Optical filters are used in various areas of science, including in particular astronomy; they are essentially the same as photographic filters, but in practice often need far more accurately controlled optical properties and precisely defined transmission curves than filters exclusively for photographic use.