Assertion: wedge prism | /r/CapableOf | refract light
Facets:
value: to offset the object of interest
type: PURPOSE
Source sentences:
text: Because the wedge prism refracts light to offset the object of interest (e.g. a tree), it can be used to determine whether or not the tree should be counted from a given point, based on the diameter at breast height of the tree and its distance from that point.