1. A Fizeau interferometer is an interferometric arrangement whereby two reflecting surfaces are placed facing each other. As seen in Fig 1, the rear-surface reflected light from the transparent first reflector is combined with front-surface reflected light from the second reflector to form interference fringes.
2. The term Fizeau interferometer also refers to an interferometric arrangement used by Hippolyte Fizeau in a famous 1851 experiment that seemingly supported the partial ether-drag hypothesis of Augustin Jean Fresnel, but which ultimately played an instrumental role in bringing about a crisis in physics that led to Einstein's development of the theory of special relativity. See Fizeau experiment.
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