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Professor Otto Scherzer
Ultramicroscopy North-Holland
10 (1982) 179-180 Publishing Company
GUEST Professor
179
EDITORIAL Otto Scherzer
Otto Scherzer, Professor Emeritus of the Technische Hochschule Darmstadt, one of the most prominent and self-willed personalities of the pioneering age of electron microscopy, died suddenly on November 15, 1982, at the age of 74. It was a sorrowful surprise for all his friends. The beginning of Otto Scherzer’s life and career recall the famous old times of theoretical physics in Germany. Born on March 9, 1909, in Passau ~ a town where the Bavarian character is already somewhat mixed with the Austrian mentality Scherzer started studies with Arnold Sommerfeld in Munich, and in 1931 at the age of only twentytwo he received his PhD for a thesis on the “Bremsstrahlung of X-rays”. Unlike other students of Sommerfeld who became intensely engaged in atomic theory (for example, his elder colleague Werner Heisenberg). Scherzer - fascinated by the detection a few years earlier of the diffraction of electron waves on crystals - turned his interest to electron physics. One year later, already as a scientist at the AEG research institute in Berlin, he began, with a conElektronensammellintribution on “elektrische sen”, a research program which was later to occupy his whole life. Together with the late Walter Glaser (Prague. Vienna) he became one of the founders of theoretical electron optics. He returned to Sommerfeld’s institute and in 1935 was appointed as full professor of theoretical physics at the Technische Hochschule Darmstadt - at the incredibly young age of twenty-six. From January 1, 1936, up to his retirement in 1977 he was an academic teacher at this university, loved by his students and held in high esteem by his colleagues. In 1936 Scherzer published a fundamental paper which discussed the lens aberrations of electrostatic and electromagnetic round lenses, showing that certain resolution limits cannot be surpassed
[l]. He was concerned with the fact that “atomic could not be achieved at moderate resolution” acceleration voltages (So-100 kV), although only a relatively small factor of 2-3 needed to be overcome. From that time on, he worked at first theoretically and in his last years also experimentally on the problem of electron-optical correction of lenses. In 1947 he published a fundamental paper on this topic [2] which introduced, among other proposals, the idea of lenses with non-rotational symmetry. This idea was surprising, because nonrotational symmetry seems primarily to introduce rather than reduce lens aberrations. Scherzer once compared a physicist working on this problem with a cleaning-woman first dirtying the kitchen by spilling sand before cleaning it. This is an example of the nice way Scherzer had of explaining basic ideas to his students. The experimental realization of his ideas was funded by research organizations (Scherzer had a small experimental laboratory in his theoretical institute similar to the one of his teacher Sommerfeld), yet it proved very slow. The requirements of precision and of mechanical and electrical stability were extraordinary. Nevertheless, Scherzer in his last years had the pleasure of seeing some real experimental progress (see also ref. [3]). Scherzer was never very fond of computers - he preferred instrumental solutions. Later, however, he recognized the earlier perhaps underestimated importance of 3D imaging for the problem of imaging atomic structures: only in three dimensions are the structures sufficiently resolved to show structural constraints which are helpful for the analysis. It is quite normal that the personal weighing of a life’s achievement depends also on the interest of the referee. I was very much impressed by his calculation of atomic images in the CTEM in 1949
[4]. This paper, in fact, is characteristic of the way Scherzer worked in the field of theoretical physics; it is perhaps also characteristic of the Sommerfeld school. Too impatient to perform lengthy calculations and to solve complicated integrals, he looked for suitable approximations everywhere. He recognized that the “strong” scattering of electrons is nonetheless weak compared to the primary beam. He introduced the linear approximation for calculating image intensities, which later became so fruitful for space frequency filtering. However, he also included the phase object principle of atomic scattering in his calculations which had been recognized by Boersch two years earlier. His deduction of the focus of optimal phase contrast (Scherzer focus) is one of the masterpieces of theoretical electron optics. All friends and colleagues of Otto Scherzer admired his enormous vitality, which was by no
means lessened by his retirement. His death after a short illness is a great loss for electron microscopy, and there is no doubt that, had he lived, he would have continued to contribute to this science. His pioneering work will remain forever as one of the fundaments of electron microscopy. Walter Hoppe Max-Planck-Institut fur Biochemie D-8033 Martinsried bei Munchen Fed. Rep. of Germany
References [I] [2] [3] [4]
0. 0. 0. 0.
Scherzer. Scherzer. Scherzer. Scherzer.
Z. Physik 101 (1936) 593. Optik 2 (1947) 114. Ultramicroscopy 9 (1982) 9 J. Appl. Phys. 20 (1949) 20.
10 (1982) 179-180 Publishing Company
GUEST Professor
179
EDITORIAL Otto Scherzer
Otto Scherzer, Professor Emeritus of the Technische Hochschule Darmstadt, one of the most prominent and self-willed personalities of the pioneering age of electron microscopy, died suddenly on November 15, 1982, at the age of 74. It was a sorrowful surprise for all his friends. The beginning of Otto Scherzer’s life and career recall the famous old times of theoretical physics in Germany. Born on March 9, 1909, in Passau ~ a town where the Bavarian character is already somewhat mixed with the Austrian mentality Scherzer started studies with Arnold Sommerfeld in Munich, and in 1931 at the age of only twentytwo he received his PhD for a thesis on the “Bremsstrahlung of X-rays”. Unlike other students of Sommerfeld who became intensely engaged in atomic theory (for example, his elder colleague Werner Heisenberg). Scherzer - fascinated by the detection a few years earlier of the diffraction of electron waves on crystals - turned his interest to electron physics. One year later, already as a scientist at the AEG research institute in Berlin, he began, with a conElektronensammellintribution on “elektrische sen”, a research program which was later to occupy his whole life. Together with the late Walter Glaser (Prague. Vienna) he became one of the founders of theoretical electron optics. He returned to Sommerfeld’s institute and in 1935 was appointed as full professor of theoretical physics at the Technische Hochschule Darmstadt - at the incredibly young age of twenty-six. From January 1, 1936, up to his retirement in 1977 he was an academic teacher at this university, loved by his students and held in high esteem by his colleagues. In 1936 Scherzer published a fundamental paper which discussed the lens aberrations of electrostatic and electromagnetic round lenses, showing that certain resolution limits cannot be surpassed
[l]. He was concerned with the fact that “atomic could not be achieved at moderate resolution” acceleration voltages (So-100 kV), although only a relatively small factor of 2-3 needed to be overcome. From that time on, he worked at first theoretically and in his last years also experimentally on the problem of electron-optical correction of lenses. In 1947 he published a fundamental paper on this topic [2] which introduced, among other proposals, the idea of lenses with non-rotational symmetry. This idea was surprising, because nonrotational symmetry seems primarily to introduce rather than reduce lens aberrations. Scherzer once compared a physicist working on this problem with a cleaning-woman first dirtying the kitchen by spilling sand before cleaning it. This is an example of the nice way Scherzer had of explaining basic ideas to his students. The experimental realization of his ideas was funded by research organizations (Scherzer had a small experimental laboratory in his theoretical institute similar to the one of his teacher Sommerfeld), yet it proved very slow. The requirements of precision and of mechanical and electrical stability were extraordinary. Nevertheless, Scherzer in his last years had the pleasure of seeing some real experimental progress (see also ref. [3]). Scherzer was never very fond of computers - he preferred instrumental solutions. Later, however, he recognized the earlier perhaps underestimated importance of 3D imaging for the problem of imaging atomic structures: only in three dimensions are the structures sufficiently resolved to show structural constraints which are helpful for the analysis. It is quite normal that the personal weighing of a life’s achievement depends also on the interest of the referee. I was very much impressed by his calculation of atomic images in the CTEM in 1949
[4]. This paper, in fact, is characteristic of the way Scherzer worked in the field of theoretical physics; it is perhaps also characteristic of the Sommerfeld school. Too impatient to perform lengthy calculations and to solve complicated integrals, he looked for suitable approximations everywhere. He recognized that the “strong” scattering of electrons is nonetheless weak compared to the primary beam. He introduced the linear approximation for calculating image intensities, which later became so fruitful for space frequency filtering. However, he also included the phase object principle of atomic scattering in his calculations which had been recognized by Boersch two years earlier. His deduction of the focus of optimal phase contrast (Scherzer focus) is one of the masterpieces of theoretical electron optics. All friends and colleagues of Otto Scherzer admired his enormous vitality, which was by no
means lessened by his retirement. His death after a short illness is a great loss for electron microscopy, and there is no doubt that, had he lived, he would have continued to contribute to this science. His pioneering work will remain forever as one of the fundaments of electron microscopy. Walter Hoppe Max-Planck-Institut fur Biochemie D-8033 Martinsried bei Munchen Fed. Rep. of Germany
References [I] [2] [3] [4]
0. 0. 0. 0.
Scherzer. Scherzer. Scherzer. Scherzer.
Z. Physik 101 (1936) 593. Optik 2 (1947) 114. Ultramicroscopy 9 (1982) 9 J. Appl. Phys. 20 (1949) 20.