Rayleigh interference refractometer

instrument

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July 13, 2026

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The Rayleigh interference refractometer is an instrument used to determine the refractive indices of gases and liquids. It operates on the principle of interference, where a beam of light is split, and one part travels through a known material before passing through the unknown substance. The resulting interference fringes, which are patterns of light and dark bands, are then compared. Displacements in these fringes reveal the refractive index of the unknown material. The refractive index itself measures how much a ray of light bends when passing from one medium to another, and it is defined by the ratio of the sine of the angle of incidence to the sine of the angle of refraction, or by the ratio of the speed of light in a vacuum to its speed in the substance.12

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optical interferometer
…physicist Lord Rayleigh described the Rayleigh interference refractometer, still widely used for determining the refractive indices of gases and liquids. It is a split-beam instrument, like the Michelson interferometer. One beam serves as a reference, while the other is passed first through a material of known index of refraction and…
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…physicist Lord Rayleigh described the Rayleigh interference refractometer, still widely used for determining the refractive indices of gases and liquids. It is a split-beam instrument, like the Michelson interferometer. One beam serves as a reference, while the other is passed first through a material of known index of refraction and…
Read More