focal point(redirected from anterior focal point)
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the point on the axis of a lens or mirror to which parallel rays of light converge or from which they appear to diverge after refraction or reflection
Collins Discovery Encyclopedia, 1st edition © HarperCollins Publishers 2005
focal point(focus) See focal length.
Collins Dictionary of Astronomy © Market House Books Ltd, 2006
focal point[′fō·kəl ‚pȯint]
The point to which rays that are initially parallel to the axis of a lens, mirror, or other optical system are converged or from which they appear to diverge. Also known as principal focus.
McGraw-Hill Dictionary of Scientific & Technical Terms, 6E, Copyright © 2003 by The McGraw-Hill Companies, Inc.