Professor Łucjan Krause, a long-term head of the Department of Physics of the University of Windsor died on July 4, 2022 in Windsor, Ontario in Canada. He was an outstanding Polish-Canadian physicist, who made important contributions to the atomic, molecular and optical physics. Born in Poznań on January 8, 1928, as a scout and Home Army soldier (nickname “Leonidas”), he took part in the Warsaw Uprising and after its failure was sent to a POW camp in Bergen-Belsen, in Germany. In 1951 after graduating from King’s College University of London, he emigrated to Canada, where he began his studies of physics at the University of Toronto. In 1955 he obtained in Toronto the PhD degree in physics under the supervision of Professor Harry Welsh in Raman spectroscopy of gases. Then for three years he worked as an associate professor of physics at the Memorial University of Newfoundland in St. John’s. In 1958 he accepted an invitation from the University of Windsor and became a head of its Department of Physics. In Windsor, Krause created a vibrant scientific centre in which he developed research program in experimental studies of inelastic atomic collisions. The main attention was focused on the excitation energy transfer between colliding atoms, the quenching of fluorescence radiation by molecular gases and, more recently, on laser spectroscopy of metal excimers. In 1963 he initiated the cooperation with Professor Aleksander Jabłoński, head of the Chair of Experimental Physics of Nicolaus Copernicus University in Toruń. Thanks to this cooperation numerous physicists, first from Toruń and later from other Polish scientific centers – as postdoctoral fellows – participated in experiments with the use of advanced laser equipment, not available in Poland at that time. In this way, Łucjan Krause contributed significantly to the development of physics in Poland. In order to pay tribute to his effort and devotion, in 1983 the Senate of Nicolaus Copernicus University awarded Professor Łucjan Krause a doctor honoris causa degree.