Alfred Pérot

Graduating from the École Polytechnique in Paris, Pérot returned to the University of Marseille, collaborating fruitfully with Charles Fabry. Their multi-beam interferometer (etlon) revolutionized spectroscopy, lasers, and telecommunications.

Pérot served as director of the testing laboratory at the Conservatoire National des Arts et Métiers and later astrophysicist at the Meudon Observatory. In 1906, his interferometric measurements established the international primary standard of length in terms of light waves, confirming the solar gravitational redshift predicted by Albert Einstein's general relativity.