degree of Doctor of Philosophy (PhD) for dissertation about the resolving power of optical systems on example of microscope. Despite many great scientific achievements in his later years, Mieczysław Wolfke judged its content the most valuable. During the stay in Zurich Mieczysław Wolfke was a member of a narrow group of physicists who created the paths of the world physics. In 1916 he started to study subject of Anode rays and – in 1917 – melting of tungsten (together with Gmür e CO company) and also on mercury Rectifiers. One year later his interests changed to carbon lamps, tungsten smelting and nitrogen combustion. At this time he published also dissertation "Über die Möglichkeit der optischen Abbildung von Molekulargittern" – (About a possibility of optical imaging of molecular gratings) – the world's first concept of holography and the second of the achievements cherished the most by himself. This thesis refers to Wolfke's stay in Karlsruhe in 1912, where he was an assistant to Professor Otto Lehmann – a physicist known as the father of Liquid crystals. In his laboratory Wolfke noticed that it was possible to first record the image on a photographic plate by illuminating the X-ray crystal and then read it with the use of additional optical unit and visible light. Dennis Gabor, during his Nobel lecture said: “I did not know at that time, and neither did Bragg, that Mieczysław Wolfke had proposed this method in 1920, but without realizing it experimentally”. In 1922, after returning to Poland, Mieczysław Wolfke took up the problem of low temperatures. In 1924 Józef Wierusz-Kowalski – physicist, professor at the Warsaw University of Technology and from 1921 – Polish ambassador in the Hague – offered him a trip to Leiden and cooperation with the Institute of Low Temperatures in Leiden, where professor H. K. Kamerlingh-Onnes and (later) Willem Keesom studied the dielectric constant of liquid helium at various temperatures. The theoretical experiments led him to the discovery of two liquid phases of helium and solidification of helium what Mieczysław Wolfke considered as the third of his greatest achievements. In the early thirties Wolfke started to organize the separated Institute of Low Temperatures at Warsaw University of Technology, even running the first installation. In 1927 Wolfke worked on the liquid helium dielectric constant and in the next year on the association in liquid dielectrics. He also started cooperation with the Polish Army in