Cornu quartz prism

Cornu quartz prism

[′kȯr·nü ‚kwȯrts ′priz·əm]
(optics)
A prism constructed of two 30° quartz prisms, left- and right-handed, used in conjunction with left- and right-handed lenses, so that the rotation of polarization occurring in one half of the optical path is exactly compensated by the reverse rotation in the other; used in a quartz spectrograph.