Sagnac effect

noun

A phenomenon encountered in interferometry that is elicited by rotation. The Sagnac effect manifests itself in a setup called a ring interferometer. A beam of light is split and the two beams are made to follow the same path but in opposite directions. To act as a ring the trajectory must enclose an area. On return to the point of entry the two light beams are allowed to exit the ring and undergo interference. The relative phases of the two exiting beams, and thus the position of the interference fringes, are shifted according to the angular velocity of the apparatus.

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Meanings

nounSagnac effect (plural Sagnac effects)

plural Sagnac effects

  1. A phenomenon encountered in interferometry that is elicited by rotation. The Sagnac effect manifests itself in a setup called a ring interferometer. A beam of light is split and the two beams are made to follow the same path but in opposite directions. To act as a ring the trajectory must enclose an area. On return to the point of entry the two light beams are allowed to exit the ring and undergo interference. The relative phases of the two exiting beams, and thus the position of the interference fringes, are shifted according to the angular velocity of the apparatus.

Origin

Named after French physicist Georges Sagnac.

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Cite this entry
APA

Sagnac effect. (n.d.). In WatkinsX Dictionary. Retrieved November 4, 2026, from https://dictionary.watkinsx.com/word/Sagnac%20effect

MLA

“Sagnac effect.” WatkinsX Dictionary, https://dictionary.watkinsx.com/word/Sagnac%20effect. Accessed November 4, 2026.

Chicago

WatkinsX Dictionary, s.v. “Sagnac effect,” accessed November 4, 2026, https://dictionary.watkinsx.com/word/Sagnac%20effect.

Source: Sagnac effect on Wiktionary, CC BY-SA 4.0.