Assertion: eyepiece's diameter | /r/HasProperty | expressed as a field-of-view number
Facets:
Source sentences:
text: The diameter of the viewfield in an eyepiece is expressed as a "field-of-view number" or field number (FN), as discussed above.
text: The diameter of the field in an optical microscope is expressed by the field-of-view number, or simply the field number, which is the diameter of the view field in millimeters measured at the intermediate image plane.