Coma

Description

One type of optical Aberration of a lens with spherical surface. When coma aberration occurs, the image cannot be focused because the light rays no longer meet at the focal plane as a point but rather as the shape of a comet. Coma is caused by various lens zones having different magnifications. A lens systems that is corrected for both Spherical aberration and coma for a single object position is called Aplanatic.

Synonyms and Related Terms

Koma (Deut.); coma (Fr.);

Sources Checked for Data in Record

• Van Nostrand's Scientific Encyclopedia, Douglas M. Considine (ed.), Van Nostrand Reinhold, New York, 1976

• Random House, Webster's Encyclopedic Unabridged Dictionary of the English Language, Grammercy Book, New York, 1997

• The American Heritage Dictionary or Encarta, via Microsoft Bookshelf 98, Microsoft Corp., 1998

• ASTM, Standard Terminology of Microscopy, Annual Book of ASTM Standards, Section 14, General Methods and Instrumentation, ASTM, E175, 75-78, May 1982

• Walter C. McCrone, John Gustave Delly, The Particle Atlas, W. McCrone Associates, Chicago, IV, 1972