We should note that this latter type of shift was successfully amplified to a considerable extent by Russian physicists using the intense light of a ruby laser whose wavelength is close to that of a transition of the potassium atom.

Laboratoire Kastler-Brossel

Professor Kastler spent most of his research career at the Ecole Normale Supérieure in Paris where he started after the war with his student Jean Brossel a small research group on spectroscopy. Kastler also wrote poetry (in German). Over the forty years that followed this group has trained many of young physicists and had a significant impact on the development of the science of atomic physics in France.

Alfred Kastler (May 3 1902 – January 7 1984) was a French physicist and Nobel Prize laureate. Kastler was born in Guebwiller (Alsace German Empire) and later attended the Lycée Bartholdi in Colmar Alsace and École Normale Supérieure in Paris in 1921. Europe my fatherland: German songs of a French European).