François Morellet a key representative of the Concrete Art movement.

François Morellet, Galerie Der Spiegel, Köln, 1966

François Morellet was a French Conceptual sculptor and light artist known for his intricate geometric forms and patterns. Born on April 30, 1925 in Cholet, France, Morellet initially made figurative paintings before turning to abstraction, painting a series of crisscrossing lines that formed squares, triangles, and other geometries. He then began to work in sculpture with neon tubes, and along with fellow artists Julio Le Parc and Francisco Sobrino, co-founded the Groupe de Recherche d’Art Visuel in 1963 to research new modes of artistic expression. Like Dan Flavin, Morellet used florescence to explore geometry as art, oftentimes splaying the tubes to create loose compositions as seen in Reflections in water deformed by the spectator (1964). His interests in Minimalism and spontaneity have earned him comparisons to Ellsworth Kelly, Sol LeWitt, and John Cage. Morellet was notably included in the major 2011 exhibition at the Guggenheim Museum in New York, “Themes & Variations. Script and Space.” He died on May 11, 2016, days after his 90th birthday. via artnet

François Morellet, Sphere-Trame, 1962