aperture

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aperture

 [ap´er-chur]
inferior aperture of minor pelvis (inferior aperture of pelvis) pelvic outlet.
numerical aperture an expression of the measure of efficiency of a microscope objective.
superior aperture of minor pelvis (superior aperture of pelvis) pelvic inlet.

ap·er·ture

(ap'er-chūr),
1. Opening. An inlet or entrance to a cavity or channel. In anatomy, a gap or hole.
See also: fossa, ostium, orifice, pore. Synonym(s): apertura [TA]
2. The diameter of the objective of a microscope.
Synonym(s): aditus [TA]
[L. apertura, an opening]

ap·er·ture

(ap'ĕr-chŭr) [TA]
1. An inlet or entrance to a cavity or channel; in anatomy, an open gap or hole.
2. The diameter of the objective of a microscope.
Synonym(s): aditus [TA] , apertura [TA] .
[L. apertura, an opening]

aperture 

An opening, or the area of a lens, through which light can pass. See pupil.
angular aperture Half of the maximum plane subtended by a lens at the axial point of an object or image. (Sometimes the full plane angle is taken as the angular aperture but this is not convenient in optical calculations.) See sine condition.
aperture of a lenticular lens That portion of a lenticular lens which has the prescribed power (British Standard).
numerical aperture An expression designating the light-gathering power of microscope objectives. It is equal to the product of the index of refraction n of the object space and the sine of the angle u subtended by a radius of the entrance pupil at the axial point on the object, i.e. n sin u.
palpebral aperture The gap between the margins of the eyelids when the eye is open. An abnormal increase in the aperture occurs in some conditions, including Graves' disease, buphthalmos, Parinaud's syndrome and retrobulbar tumour. An abnormal decrease in the aperture occurs in some conditions, including ptosis, microphthalmos and ophthalmoplegia (Figs. A15 and A16). Syn. interpalpebral fissure (this term is more accurate although used infrequently); palpebral fissure. See exophthalmos.
aperture plane See aperture plane.
aperture ratio See relative aperture.
relative aperture The reciprocal of the f number. It is therefore equal to the ratio of the diameter of the entrance pupil to the primary focal length of an optical system. Syn. aperture ratio. Note: the definition of this term is not universally accepted; some authors define it as the reverse of the above. See antimongoloid slant; f number.
Fig. A15 Palpebral aperture PA and corneal apex CAenlarge picture
Fig. A15 Palpebral aperture PA and corneal apex CA
Fig. A16 Average dimensions of the normal palpebral aperture of a Caucasian eyeenlarge picture
Fig. A16 Average dimensions of the normal palpebral aperture of a Caucasian eye

ap·er·ture

(ap'ĕr-chŭr) [TA]
1. [TA] Opening. An inlet or entrance to a cavity or channel. In anatomy, a gap or hole.
Synonym(s): apertura.
2. The diameter of the objective of a microscope.
See also: fossa, ostium, orifice
Synonym(s): aditus [TA] .
[L. apertura, an opening]
References in periodicals archive ?
With active cooling, the 2400B-405 model can emit greater than 20W from a 7.5mm diameter clear aperture with a 0.66 numerical aperture (NA).
From our previous M0201 assembly experience, 120 x 140[micro]m size stencil apertures produced prints containing too much solder paste volume.4 From this experience it is logical to consider reducing the aperture size to shrink the print deposit volume.
Current iron-sight options are fewer and vintage apertures from yesteryear come dear.
The piriform aperture is an anatomical structure formed by several bones that are part of the face.
It features what Samsung calls 'dual aperture' lens and this is a big deal, so much that the company themed the Galaxy S9 'The Camera Reimagined'.So what is it about this reimagined camera?Let's start with the aperture.
The S9's lens has native aperture of f/1.5, which is the widest aperture in a phone camera's lens till now.
Figure 6 shows the velocity and hydraulic gradient curve for 4 fracture apertures. The relationship between the velocity u and the hydraulic gradient J for the large fracture aperture and high velocity can be well described by a power function, and the flow velocity and the hydraulic gradient have deviated from the linear relationship [22-24].
The late NM/2 and current NM/2A bases were designed to accommodate hooded apertures. Sight bases rarely wear out, so I wouldn't worry about keeping a spare on hand.
However, significant electromagnetic leakage can occur from the adjacent space of the enclosure through slots, apertures, connecting lines, and so forth, in which case the transient voltage and current induced by the EMI may degrade the performance of some sensitive components of the equipment and even damage them.
"We are combining energies from multiple apertures so electrically they look like one," Potter told National Defense.