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focal plane

noun Optics.

a plane through a focal point and normal to the axis of a lens, mirror, or other optical system.Compare principal plane.
the transverse plane in a telescope where the real image of a distant view is in focus.

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Words nearby focal plane

focal epilepsy, focal glomerulonephritis, focal infection, focal length, focal necrosis, focal plane, focal point, focal ratio, focal reaction, focal segmental glomerulosclerosis, focal seizure

Origin of focal plane

First recorded in 1890–95
Dictionary.com Unabridged Based on the Random House Unabridged Dictionary, © Random House, Inc. 2019

British Dictionary definitions for focal plane

focal plane

noun

the plane that is perpendicular to the axis of a lens or mirror and passes through the focal point
the plane in a telescope, camera, or other optical instrument in which a real image is in focus
Collins English Dictionary - Complete & Unabridged 2012 Digital Edition © William Collins Sons & Co. Ltd. 1979, 1986 © HarperCollins Publishers 1998, 2000, 2003, 2005, 2006, 2007, 2009, 2012