ap·la·nat·ic /ˌæpləˈnætɪk/
 等光程; 不暈的
 ap·la·nat·ic /ˌæpləˈnætɪk, ˌeplə-/ 形容詞
 等光程的,消球面差的,不暈的,齊明的
 Ap·la·nat·ic a.  Opt. Having two or more parts of different curvatures, so combined as to remove spherical aberration; -- said of a lens.
 Aplanatic focus of a lens 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.
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 aplanatic
      adj : free from or corrected for spherical aberration; "an
            aplanatic mirror"