half-wave plate

[ haf-weyv, hahf- ]
/ ˈhæfˌweɪv, ˈhɑf- /

noun Optics.

a crystal thin enough to cause a phase difference of 180° between the ordinary and extraordinary rays of polarized light, thereby changing the direction of the plane of polarization.

Origin of half-wave plate

First recorded in 1900–05
Dictionary.com Unabridged Based on the Random House Unabridged Dictionary, © Random House, Inc. 2019