BERNARD LYOT

Bernard Lyot 1897-1952

Bernard Lyot was born February 27, 1897 in Paris, the son of a surgeon, he lost his father at the age of seven. He studied engineering and graduated from the Graduate School of electricity.
In 1917 he obtained a position at the Ecole Polytechnique in Paris, as assistant to the physicist Alfred Pérot. Probably due to the latter, Lyot gets a place at the Meudon Observatory in 1920, which will be attached to the end of his life.
Lyot spent his life studying optical phenomena extremely difficult to detect. It manufactures instruments, designs early devices that do not suffer very little to change.
In 1923, he developed the principle of photoelectric polarimeter he realized in 1950 with the arrival of electron multipliers.
The study of the polarization of the light of the stars, Lyot preoccupy his life. His doctoral thesis, which he completed in 1929, deals with the polarization of light reflected from the surfaces of planets, which allows to determine their structure. He also predicted that Mars is subject to huge dust storms, which will be actually observed by spacecraft in the 1970s.
To measure the polarization of light from the solar corona, Lyot invented the instrument that allows an artificial eclipse.
He uses a mask that blocks light and rejects the solar disk out of the telescope.
Lyot and creates an instrument for observing the solar corona, except very short periods of total eclipse.

He tries his instrument at the Pic du Midi in the Pyrenees during the summer of 1930.
In 1931, Lyot succeeded in obtaining the first photograph of the inner ring of the Sun, taken out of an eclipse. It then spectroscopic observations of the crown in the near infrared, where he discovered several new spectral lines.
To observe selectively in the main coronal rays, Lyot filter develops a very narrow spectral bandwidth. This filter consists of a superposition of birefringent crystals such as calcite and quartz filters and Polaroids. Today, it produces very versatile Lyot filters whose bandwidth can be selectively moved to a spectral range of several hundred nanometers.
Using the filter and the coronagraph, Lyot succeeded in obtaining in 1939 a film recording the movements of spectacular solar prominences.
Lyot's death tragically occurred in Egypt, on his return from an expedition to eclipse the Sun, in Khartoum, Sudan. It seems he suffered a heart attack in Cairo, April 2, 1952.

Image: Bernard Lyot obtained the first photograph of the inner ring of the Sun.