optic axis   (TTS Sound)

The noun optic axis has 2 senses

• optic axis -- (in a doubly refracting crystal, the line in the direction of which no double refraction occurs; "a crystal may have either one or two optic axes")


• principal axis, optic axis -- (a line that passes through the center of curvature of a lens so that light is neither reflected nor refracted; "in a normal eye the optic axis is the direction in which objects are seen most distinctly")