Apertometer
an instrument for measuring the angular and of the objective lens of a microscope.
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- Aperture card
a punched-card mounting for microfilmed pages.
- Aperture mask
. a perforated metal plate situated behind the faceplate of a color television picture tube and having holes aligned to insure that each of three electron beams strikes only its corresponding red, green, or blue phosphor dot. noun (television) a perforated metal sheet mounted close to the phosphor-dotted screen in some colour television tubes. the […]
- Aperture-priority
of or relating to a semiautomatic exposure system in which the photographer presets the aperture and the camera selects the shutter speed.
- Aperture synthesis
(in radio astronomy) a technique that combines the inputs of a set of radio telescopes to obtain a greater resolution of images than is possible with a single member of the set. noun an array of radio telescopes used in radio astronomy to simulate a single large-aperture telescope. some such instruments use movable dishes while […]
- Apetalous
having no petals. historical examples rivina, ri-vī′na, n. a genus of apetalous plants, the pokeweed family. chambers’s twentieth century dictionary (part 3 of 4: n-r) various our genera are apetalous and with the calyx free from the ovary. the manual of the botany of the northern united states asa gray stackhousia juncea, according to clarke, […]