aperture (redirected from Numerical aperture)

aperture /ap·er·ture/ (ap´er-cher) opening.

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piriform aperture  the anterior end of the bony nasal opening, connecting the external nose with the skull.

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ap·er·ture (pr-chr)

n.

1. An opening, such as a hole, gap, or slit.

2. A usually adjustable opening in an optical instrument, such as a microscope, a camera, or a telescope, that limits the amount of light passing through a lens or onto a mirror.

3. The diameter of such an opening.

4. The diameter of the objective of a telescope or microscope.

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aper·tural adj.

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aperture,

n an opening such as in bone.

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aperture

an opening.

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nasal aperture

the opening on the skull bounded by the nasal and incisive bones.

nasomaxillary aperture

the connecting aperture between the middle nasal meatus and the maxillary sinuses.

numerical aperture

measure of efficiency of a microscope objective proportional to the square root of the amount of light entering the instrument.