Date of Birth: 07/11/1897
Place of birth: Alencon
Born in Alencon, first he worked as a chemist, since 1925 - member of the Strasbourg Observatory. On the initiative of Danjon he moved to Paris, where he was director of the optical laboratory. There started production of the first mirror for the reflectors. In 1943-1968 - astronomer at the Paris Observatory. A member of the Bureau des Longitudes in Paris since 1946, its President (1951-1953). Member of the Paris Academy of Sciences (1954), its president in 1968.
Major works in the field of astronomical optics and instrumentation. He developed a number of ways to reduce the optical aberrations of the mirror and lens telescopes and spectrographs. Created by a mechanical system that reduces the influence of gravity to form reflector mirror; system used in telescopes and large at present. Establish rules mount mirrors. Recommended use of ventilation in the large telescopes to reduce the effects of air turbulence. According to his ideas and with his active participation, several new large reflectors were built. He took an active part in the creation of an observatory of Haute Provence (in 1964-1973 - President of its Steering Committee), the European Southern Observatories, Mayna Kea (Hawaii), etc. Together with A.Danzhonom developed a methodology to assess performance astroclimatic items by type of diffraction images of stars. , widely used in the 1940-1960-ies. Co-author of the well-known book "Spotting scopes and telescopes" (1935).
Member of the Belgian Royal Academy of Sciences, Literature and Fine Arts, Vice-President of the International Astronomical Union (1952-1958). Most of the scientific prize of the city of Paris (1961).
It is named after a crater on the Moon.