Describing a surface of a lens or mirror that has been given an optical figure which is not part of a sphere. The most common aspheric surface is the paraboloid, widely used for telescope mirrors. Another common aspheric surface is that used for the corrector plates of Schmidt–Cassegrain telescopes. In objective lenses most surfaces are spheroidal, one surface being aspheric to correct for aberrations.
Subjects: Astronomy and Astrophysics.