Lens (geometry)

In geometry, a lens is a biconvex (convex-convex) shape comprising two circular arcs, joined at their endpoints. If the arcs have equal radii, it is called a symmetric lens, otherwise is an asymmetric lens. A concave-convex shape is called a lune. The vesica piscis is one form of a symmetrical lens; the term is also used for lenses generally.

In common usage, the term lens is also used to describe the shape of a three-dimensional object obtained by rotating a two-dimensional lens about its narrow axis of symmetry. Such a shape is described as lenticular and is most commonly used for focussing and dispersement of electromagnetic radiation.

See also

• Mrs. Miniver's problem
• Beta skeleton

References

• Eric W. Weisstein. "Lens". MathWorld. Retrieved June 13, 2005.  which in turn cites
  • Pedoe, D. (1995). "Circles: A Mathematical View, rev. ed.". Washington, DC: Math. Assoc. Amer. 
  • Plummer, H. (1960). An Introductory Treatise of Dynamical Astronomy. York: Dover. 
  • Watson, G. N. (1966). A Treatise on the Theory of Bessel Functions, 2nd ed. Cambridge, England: Cambridge University Press.