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.
(television) a perforated metal sheet mounted close to the phosphor-dotted screen in some colour television tubes. The holes are positioned so that each of the three electron beams strikes the correct phosphor dot producing the required colour mixture in the image
of or relating to a semiautomatic exposure system in which the photographer presets the aperture and the camera selects the shutter speed.
- Aperture ratio
- 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 […]
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, […]