focal point(redirected from posterior focal point)
Also found in: Dictionary, Thesaurus, Medical, Legal.
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
focal point(focus) See focal length.
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.