Meaning of optic axis

op'tic ax'is

Pronunciation: [key]
— Crystall. Crystall.
  1. (in a crystal exhibiting double refraction) the direction or directions, uniaxial or biaxial, respectively, along which this phenomenon does not occur.
Random House Unabridged Dictionary, Copyright © 1997, by Random House, Inc., on Infoplease.
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