01 a. Having two or more parts of different curvatures, so combined as to remove spherical aberration; -- said of a lens.
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1.
Having two or more parts of different curvatures, so combined as to remove spherical aberration; -- said of a lens.(Opt.)
Phrases & compounds
Aplanatic focus —
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.