wollastons doublet

from The Collaborative International Dictionary of English v.0.48
Wollaston's doublet \Wol"las*ton's dou"blet\ [After W. H.
   Wollaston, English physicist.] (Optics)
   A magnifying glass consisting of two plano-convex lenses. It
   is designed to correct spherical aberration and chromatic
   dispersion.

   Note: Under "wollastonite" the eponymous inventor is
         described as a chemist.
         [Webster 1913 Suppl. +PJC]
    

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