Aplanatic

a.

1.

(Opt.) Having two or more parts of different curvatures, so combined as to remove spherical aberration; - said of a lens. Aplanatic focus (Opt.) the point or focus from which rays diverging pass the lens without spherical aberration. In certain forms of lenses there are two such foci; and it is by taking advantage of this fact that the best aplanatic object glasses of microscopes are constructed.

Adj.

1.

aplanatic - free from or corrected for spherical aberration; "an aplanatic mirror"

corrected, optics