Assertion: telescope's lens | /r/CapableOf | focus light
Facets:
value: to a flat secondary mirror
type: TRANSITIVE-OBJECT
value: at the ground floor
type: LOCATION
value: to form an image
type: PURPOSE
Source sentences:
text: The front lens (the objective) focuses light to form an image in the back.
text: A telescope's ability to resolve small detail is directly related to the diameter (or aperture) of its objective (the primary lens or mirror that collects and focuses the light), and its light gathering power is related to the area of the objective.
text: Once the person looks into the eyepiece, a concave lens will gather and focus more light than the eye could so that a magnified image can be seen.
text: A reflector telescope uses two mirrors instead of a lens to gather and focus light.
text: A diffraction grating (a surface containing thousands of microscopic parallel grooves per inch) is placed at the point where the lens should focus light.
text: Two mirrors feed sunlight to a 12-inch (30 cm) lens which focuses light down at the ground floor.
text: Uses a parabolic mirror instead of a lens to focus light.
text: Reflecting telescopes use a huge concave parabolic mirror instead of a lens to gather and focus the light to a flat secondary mirror that in turn reflects the image out of an opening at the side of the main tube.