When was the electron microscope born?

The electron microscope was first developed by Knoll and Ruska in the laboratory, and then mass-produced by Siemens in 1939. The following are several important developments of electron microscope, and several breakthroughs in materials science are discussed. When the Swedish Nobel Prize Committee awarded half of the 1986 physics prize to E. Ruska, the prize was "for its contribution to the basic research of electron optics and the design of the first electron microscope". Under the guidance of Knoll, Ruska began to study the focus of cathode rays from 1928, when he was doing an associate doctoral thesis in the high-voltage electrical engineering laboratory in Berlin. He first focused the metal mesh with a magnetic lens to get the magnified image of 13 times, and then got the magnified image of 17 14 times with a double lens [1 2], and realized the electron microscope imaging in the laboratory. He developed an electron microscope with von Borris from 1930 to 1933 in Siemens. He introduced pole shoes and a projection mirror, and finally got an image with a magnification of 12000 times, which was higher than that of an optical microscope, announcing the birth of the first electron microscope (for the development process of the electron microscope, see literature [3-8] Note that the word "invention" of the electron microscope is avoided in this praise, which is not a momentary carelessness, but the result of careful consideration. Because M.Rüdenberg of Siemens filed a patent application for manufacturing an electron microscope with a magnetic lens or an electrostatic lens with the patent offices of Germany, France and the United States on May 28th, 193 1 (this is the first time that the term electron microscope appeared), and in February, 1932 and1992 respectively. AEG, a German general electric company, began to study electrostatic lens imaging under the leadership of Bruges in19311,and obtained the emission electron image of the filament coated with oxide. Under the opposition of AEG company, two patent applications for electron microscope by Lü denberg were not approved by the West German Patent Office until after the war 1953 and 1954. From the perspective of patent priority, Ludenberg should be the inventor of the electron microscope. Ludenberg is a famous electronic physicist. He is not only the chief engineer of Siemens Science and Technology Department, but also a professor of electrical engineering department in Berlin. Rich in knowledge, experience and foresight. But he has never done magnetic lens imaging work, and his patent application is all based on theoretical speculation. According to the recollection of Ludenberg and his son afterwards, 1930, his other son got polio, which was caused by a virus with limited resolution, and the optical microscope could do nothing about it. For this reason, Ludenberg thought of using X-rays or electron beams to make microscopes with higher resolution [8]. But he has never published a paper in this field, and he is not well-known in the field of electron microscopy. Ruska and Noel have opinions on the patent application for electron microscope of Ludenberg. Because in May of 193 1, Ludenberg's assistant, M. Steenbeck, visited Noel's laboratory, learned about ruska's experimental results, and saw the manuscript of an academic report on ruska's work that Noel will do on June 4th, entitled "The design of cathode-ray oscilloscope and the principle of new structure". In their first paper, they did not mention the electron microscope. Just a few days before Knohl published his academic report on June 4th, Ludenberg, on behalf of Siemens, submitted a patent application for electron microscope to German, French and American patent offices on May 28th. So it is understandable that Noel and ruska have some doubts. However, the dispute about the invention right of electron microscope did not continue. First, Ludenberg moved to Britain after Hitler began to persecute Jews 1936, and went to the United States two years later, and then World War II broke out. Secondly, Ruska and Von Borries joined Siemens in February 1937, and in February 1939, the first commercial electron microscope with a resolution of 7 nm and a magnification of 30,000 times was manufactured. They belong to the same company as Rüenberg (the patent right mainly belongs to Siemens), so it is not convenient to argue about the right of invention. Then the second world war broke out, and the urgency of the war covered up this controversy. In addition, besides Noel-ruska and Ludenberg vying for the priority of inventing the electron microscope, Siemens and AEG are also arguing endlessly. In order to settle these disputes, the Prussian Academy of Sciences, the highest academic group in Germany, awarded the Leibniz Silver Award to blucher of AEG on June 3rd 194 1. Mahl and Boersch and Siemens Knoll, Ruska, Von Borries and Von Ardenne, the result is happy. After the war, Tinback worked in the former Soviet Union and did not return to East Germany until July 1956. At that time, Keno also returned to West Germany from the United States. He still remembers that Steenbeck applied for a patent in Ludenberg and visited his laboratory, so he wrote a letter to Steenbeck on June 5438+0960 17 10, hoping to know the specific situation at that time. In the reply of165438+1October 8th, Steenbeck admitted that he reported to Luddenberg after his visit, and stated that "Luddenberg's application (patent: translator plus) must be the result of my visit to you, and it must also be inspired by my experience" [5]. As soon as Tinback's letter was published, public opinion was inclined to ruska's side. ruska won the Nobel Prize 50 years after he invented the electron microscope. However, ruska has never claimed to be the inventor of the electron microscope, only that he is "Urh Bo". The title of the Nobel lecture he gave after winning the Nobel Prize was "The Development of Electron Microscopy and Electron Microscopy" [4]. The word "invention" was not used in the report, and Ludenberg was not mentioned. Despite this, although the old Ludenberg passed away, his two sons have been preaching their father's attainments and foresight in electronic physics in the United States [8]. Time and again, before his father put forward the concept of electron microscope, Knoll and Ruska had been talking about cathode-ray oscilloscopes (such as the title of document 1). Bruges of AEG, a German company, disagreed, thinking that ruska was not the only one who contributed to the birth of the electron microscope. It seems that Knohl and ruska are immersed in experiments and talk about the facts. After discovering a new phenomenon, they didn't raise it to rational understanding. So at first, their understanding was limited to the focusing phenomenon of cathode ray tubes, and their universal and far-reaching significance could not be seen. 1925, de Broglie pointed out the duality theory of particles and electron waves. 1927, Thomson discovered electron diffraction in Britain, and Davidson and Germany discovered electron diffraction in the United States at the same time. After that, it naturally uses electronic imaging. But Knohl and ruska didn't understand this truth when they focused cathode rays. When Houtermans proposed the fluctuation of electrons to ruska, ruska was greatly disappointed at first, thinking that the resolution would be limited by fluctuation again. However, I soon got excited again, because according to the de Broglie equation, I calculated that the wavelength of electrons is five orders of magnitude smaller than the wavelength of light waves "[3]. Ludenberg is a theorist who seems to be unknown in the field of electron microscope, but after being inspired by the experimenter, he immediately thought of making electron microscope with electromagnetic lens, which opened up a new field. He just picked a cheap one and refused to admit that it was inspired by practice. Although he attended the lecture at 193 1 and sat in the first row of Knoll, he didn't say a word during the discussion, nor did he disclose that he had submitted a patent application for electron microscope a week ago. It can be seen that he is very shrewd and has bad intentions. However, he is a chess player after all. For the first time, he realized that he could make an electron microscope by imaging with an electromagnetic lens, and the name electron microscope first appeared in his patent application. We can also see the importance of integrating theory with practice in scientific research from this incident. The invention of electron microscope opened up a way to observe atoms directly, and it should have won the Nobel Prize decades ago. Because of the above relationship, it was not until 50 years later that all other controversial people died that ruska, who deserved this honor and was the only one who survived, was awarded. Ruska died two years after winning the prize. Fortunately, he lived long, otherwise he would have missed the Nobel Prize. Ruska has been engaged in the research and production of electron microscope all his life. He not only successfully developed the first electron microscope with higher resolution than optical microscope in the laboratory, but also personally participated in the design and manufacture of commercial electron microscope. After World War II, he returned to Siemens, and in 1954, he produced an electron microscope Elmiskop with electron diffraction function. He used a double condenser to reduce the irradiation area of the electron beam and the temperature rise of the sample, and used a cold trap to reduce the pollution of the sample, which was very popular with users. A few years later, the University of Cambridge in England bought eight such electron microscopes. Hirsch et al. observed the dislocation movement in 1955 ~ 1956 metal thin film with this type of electron microscope, which proved the correctness of dislocation theory. After that, the application of electron microscope in materials science began to spread all over the world like mushrooms after rain. Later, ruska became the director of Fritz2Haber Institute of Max Planck Institute (Laue was the first director after World War II), and was in charge of the research of electron optics and electron microscope until his retirement. As ruska himself admits, he is an engineer, and his theoretical attainments are not high. However, with a rare persistent spirit, he constantly innovated electron microscope technology in the case of war damage, lack of funds and shortage of manpower, and finally achieved great achievements. He deserves the Nobel Prize in Physics!