Jean-Daniel Colladon

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Jean-Daniel Colladon (born on 15 December 1802 in Geneva and died on 30 June 1893) was a Swiss physicist. He studied law but then worked in the labs of Ampère and Fourier. He received an Académie des Sciences award with his friend Charles Sturm for their measurement of the speed of sound in water in Lake Geneva in 1826. He then became professor of mechanics at Ecole Centrale Paris in 1829. He returned to Switzerland in 1839 and organised the gas lighting of Geneva and Naples.^[1]

In 1841, Colladon demonstrated Total internal reflection for the first time. Initially intending to show the fluid flow through various holes of a tank and the breaking up of water jets but stymied by the lack of a sight of the water jet provided to the audience, Colladon used a tube to collect and pipe sunlight to the lecture table; the light was trapped by the TIR of the tube until the water jet, upon which edge the light incidented at a glancing angle, broke up and carried the light in a curved flow. He reported this experiment to a wider audience in the Comptes rendus, the French Academy of Sciences' journal, in 1842. His experiments, alongside those of Auguste de la Rive (who demonstrated Colladon's experiment using electric arc light), Jacques Babinet (who, separately, had created the same effect using candlelight and a glass bottle), and John Tyndall (who, in 1870, demonstrated that light used internal reflection to follow a specific path using a jet of water that flowed from one container to another and a beam of light) formed one of the core principles of modern-day optical fiber.