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 periodicals archive ?
123136: apertural (A), lateral (B, C), umbilical (D) and apical (E) views; (F, G) small-sized specimen from Ghana, Atewa Range Forest Reserve, RMNH.
The shell of P liberiana is smaller and has less strong apertural dentition.
4 11 11 Apertural lip in lateral view strongly curved and arching forward.
the apertural dentition is more complex and the umbilicus is retained and lined with callus.
Remarks: This species is distinctive amongst south-western Indian Ocean chilodontids on account of its relatively large size, coarse sculpture and well-developed apertural dentition.
Outer lip lacking external varix, but thickened internally and bearing up to 15 denticles; denticles ridge-like, more or less in a single row and usually alternating in strength, that nearest columella usually strongest and separated from basal columella tooth by a U-shaped notch; edge of outer lip flaring; interior highly nacreous, not spirally lirate (except at apertural thickening), but somewhat angled beneath cords of external surface.
stictum (see below), particularly in terms of size, coloration and apertural dentition.
It is certainly true that Vaceuchelus species lack the distinctive basal columella dentition of some chilodontid genera, but a number of species still retain some form of apertural dentition.
adamsiana is that it is a relatively widely distributed taxon (north-eastern Eastern Cape to northern KwaZulu-Natal, from the coast to altitudes of ca 1300 m) and it correspondingly exhibits considerable variation in size, shell proportions and strength of apertural dentition (Bruggen 1980; Herbert & Kilburn 2004).
2G), as well as larger, broader specimens with strong apertural dentition from the coast (Figs 2C, 2D form impervia) and a somewhat disjunct population of similarly large specimens from the central coastal area of the Transkei region, Eastern Cape (Fig.
It appears that the superficial thickening of the columellar lip, originally considered an apertural process, is of rare occurrence and has so far only been found in the type material.
As regards shape and apertural dentition, the extremely limited type material also represents a slightly aberrant population.