tiqe-ye nin-mowj (#)
Fr.: lame demi-onde
A plate of optical material whose thickness is such that the phase difference between the extraordinary and ordinary rays after passing through the place is exactly one-half cycle. It can serve to rotate the plane of polarization of a light beam.
Fr.: lame quart d'onde
A plate of doubly refracting material cut parallel to the optic axis of the crystal and of such a thickness that a phase difference of 90° is introduced between the ordinary and extraordinary rays for light of a particular wavelength. → half-wave plate.
tiqe-ye mowj (#)
Fr.: lame à retard
An optical element that retards the phase of one plane of vibration of light relative to the plane at right angles. The two beams then recombine to form a single beam with new polarization characteristics. A typical wave plate is a birefringent crystal with a carefully chosen orientation and thickness. Also known as → retardation plate. A → half-wave plate creates a half-wave retardation. See also → quarter-wave plate.