aperture

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aperture

Physics
a. a usually circular and often variable opening in an optical instrument or device that controls the quantity of radiation entering or leaving it
b. the diameter of such an opening

aperture

The diameter of the unobscured portion of the objective lens in a refracting telescope or of the primary mirror in a reflector. In a radio telescope it is the physical size of the antenna. As the aperture is increased, the telescope gathers more light, radio waves, etc., and thus will discern fainter objects: the radiation-gathering power depends on area, i.e. on the square of the aperture. A larger aperture also produces a smaller Airy disk and so has greater spatial resolution.

Aperture

An opening for the purpose of admitting light.

aperture

[′ap·ə‚chər]
(electronics)
An opening through which electrons, light, radio waves, or other radiation can pass.
(graphic arts)
A rectangular cutout on an aperture card.
(optics)
The diameter of the objective of a telescope or other optical instrument, usually expressed in inches, but sometimes as the angle between lines from the principal focus to opposite ends of a diameter of the objective.

aperture

(1) An orifice. It often refers to an opening in which light is allowed to pass in optical systems such as cameras and lasers. See f-stop and numerical aperture.

(2) (Aperture) A photo editing and management application for the Mac from Apple. Introduced in 2005 and used by professional photographers, Aperture provides sophisticated touch-up tools and works with the iPhoto library. See iLife.
References in classic literature ?
This last to the dead Wieroo as he stooped and dragged the corpse to the central shaft, where he raised it to the aperture and let it slip into the tube.
Then before I reached the aperture I heard the yelp of a staghound.
But instead of the darkness, and the thick and mephitic atmosphere he had expected to find, Dantes saw a dim and bluish light, which, as well as the air, entered, not merely by the aperture he had just formed, but by the interstices and crevices of the rock which were visible from without, and through which he could distinguish the blue sky and the waving branches of the evergreen oaks, and the tendrils of the creepers that grew from the rocks.
That was, in fact, a marvellous grimace which was beaming at that moment through the aperture in the rose window.
Unlike Slightly's door, it filled the aperture [opening], so that he could not see beyond it, nor could the one knocking see him.
Above him, through the aperture, Werper could see sunlight glancing from massive columns, which were twined about by clinging vines.
On the floor beside the aperture lay a headless male body of almost heroic proportions, and on either side of this stood a heavily armed warrior, with drawn sword.
There were no stairs from the upper floor to the garret above, this ascent being made by means of a wooden ladder which De Vac pulled up after him, closing and securing the aperture, through which he climbed with his burden, by means of a heavy trapdoor equipped with thick bars.
Big fella shark-fish, that fella leg stop 'm along him," the ancient grinned, exposing a horrible aperture of toothlessness for a mouth.
Each superintendent took his post by the aperture of the run.
When the oat-spry horse had hedged a little his first spurt of speed Jerry broke the lid of his cab and called down through the aperture in the voice of a cracked megaphone, trying to please:
In the trap-door itself was found a square aperture cut in the wood, apparently with some exceedingly sharp instrument, just behind the bolt which fastened the door on the inner side.