Charles Fabry in the context of "Foreign Member of the Royal Society"

The ozone layer or ozone shield is a region of Earth's stratosphere that absorbs most of the Sun's ultraviolet radiation. It contains a high concentration of ozone (O₃) in relation to other parts of the atmosphere, although still small in relation to other gases in the stratosphere. The ozone layer peaks at 8 to 15 parts per million of ozone, while the average ozone concentration in Earth's atmosphere as a whole is about 0.3 parts per million. The ozone layer is mainly found in the lower portion of the stratosphere, from approximately 15 to 35 kilometers (9 to 22 mi) above Earth, although its thickness varies seasonally and geographically.

The ozone layer was discovered in 1913 by French physicists Charles Fabry and Henri Buisson. Measurements of the sun showed that the radiation sent out from its surface and reaching the ground on Earth is usually consistent with the spectrum of a black body with a temperature in the range of 5,500–6,000 K (5,230–5,730 °C), except that there was no radiation below a wavelength of about 310 nm at the ultraviolet end of the spectrum. It was deduced that the missing radiation was being absorbed by something in the atmosphere. Eventually the spectrum of the missing radiation was matched to only one known chemical, ozone. Its properties were explored in detail by the British meteorologist G. M. B. Dobson, who developed a simple spectrophotometer (the Dobsonmeter) that could be used to measure stratospheric ozone from the ground. Between 1928 and 1958, Dobson established a worldwide network of ozone monitoring stations, which continue to operate to this day. The "Dobson unit" (DU), a convenient measure of the amount of ozone overhead, is named in his honor.

Henri Buisson (French: [ɑ̃ʁi bɥisɔ̃]; 1873–1944) was a French physicist. Buisson and Charles Fabry discovered the ozone layer in 1913.

Buisson was born on 15 July 1873 in Paris and died on 6 January 1944 in Marseille, at age 70.

Jean-Baptiste Alfred Perot (French: [pəʁo]; 3 November 1863 – 28 November 1925) was a French physicist.

Together with his colleague Charles Fabry he developed the Fabry–Pérot interferometer in 1899.

In optics, a Fabry–Pérot interferometer (FPI), or etalon, is an optical cavity made from two parallel reflecting surfaces (i.e.: thin mirrors). Optical waves can pass through the optical cavity only when they are in resonance with it. It is named after Charles Fabry and Alfred Perot, who developed the instrument in 1899. Etalon is from the French étalon, meaning "measuring gauge" or "standard".

Etalons are widely used in telecommunications, lasers and spectroscopy to control and measure the wavelengths of light. Recent advances in fabrication technique allow the creation of very precise tunable Fabry–Pérot interferometers. The device is technically an interferometer when the distance between the two surfaces (and with it the resonance length) can be changed, and an etalon when the distance is fixed (however, the two terms are often used interchangeably).