astigmatic surfaces

astigmatic surfaces

[¦a·stig‚mad·ik ′sər·fəs·əs]
(optics)
Two surfaces containing the astigmatic foci of points in a plane perpendicular to the optical axis of an astigmatic system.
McGraw-Hill Dictionary of Scientific & Technical Terms, 6E, Copyright © 2003 by The McGraw-Hill Companies, Inc.