APERTURE

Aperture

In optics, an aperture is a hole or an opening through which light travels. More specifically, the aperture of an optical system is the opening that determines the cone angle of a bundle of rays that come to a focus in the image plane. The aperture determines how collimated the admitted rays are, which is of great importance for the appearance at the image plane. If an aperture is narrow, then highly collimated rays are admitted, resulting in a sharp focus at the image plane. If an aperture is wide, then uncollimated rays are admitted, resulting in a sharp focus only for rays with a certain focal length. This means that a wide aperture results in an image that is ...

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aperture

Noun

  1. An opening; an open space; a gap, cleft, or chasm; a passage perforated; a hole; as, an aperture in a wall.
    An aperture between the mountains. --Gilpin.
    The back aperture of the nostrils. --Owen.
  2. Something which restricts the diameter of the light path through one plane in an optical system.
  3. The diameter of the aperture (in the sense above) which restricts the width of the light path through the whole system. For a telescope, this is the diameter of the objective lens. e.g. a telescope may have a 100 cm aperture.
  4. The (typically) large-diameter antenna used for receiving and transmitting radio frequency energy containing the data used in communication satellites, especially in the geostationary belt. For a comsat, this is typically a large reflective dish antenna; sometimes called an array.
  5. The maximum angle between the two generatrices.
    If the generatrix makes an angle θ to the axis, then the aperture is 2θ.


The above text is a snippet from Wiktionary: aperture
and as such is available under the Creative Commons Attribution/Share-Alike License.

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