quarter-wave plate

instrument

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Last updated

July 13, 2026

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A quarter-wave plate is a crystal plate that alters the phase difference between the two components of polarized light that pass through it by one-fourth of a cycle. This optical instrument is a type of wave plate.12

When light enters certain crystals, a phenomenon called double refraction occurs, splitting the light into ordinary and extraordinary rays. If a crystal is prepared so that the path difference for these rays is one-quarter of the wavelength of the light, it functions as a quarter-wave plate. This process can be used to produce circularly polarized light.3

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radiation
Double refraction
…a crystal is called a quarter-wave plate, and the reality of the circular polarization is shown by the fact that, when the quarter-wave plate is suitably suspended and irradiated, a small torque—that is, twisting force—can be shown to be exerted on it. Thus, the action of the crystal on the…
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…a crystal is called a quarter-wave plate, and the reality of the circular polarization is shown by the fact that, when the quarter-wave plate is suitably suspended and irradiated, a small torque—that is, twisting force—can be shown to be exerted on it. Thus, the action of the crystal on the…
Read More