optic axis

English

Noun

optic axis (plural optic axes)

1. The optical axis. [from 17th c.]
   • 1665, Robert Hooke, Micrographia, section XXXIX:

     [B]inocular creatures can in an instant […] move their eyes so as to direct the optick Axis to any point […].

2. (crystallography, mineralogy) The direction in which a ray of light passing through a crystal does not suffer double refraction. [from 19th c.]