The Early Electron Microscopes: A critical Study

ARTICLE IN PRESS

The Early Electron Microscopes: A Critical Study✶ John van Gorkom , with the cooperation of Dirk van Delft and Ton van Helvoort

Contents Part 1. Conceiving the Idea 1. Ernst Ruska, Max Knoll and the Technische Hochschule 1.1 Background 1.2 Ernst Ruska’s First Assignment in 1928–1929 1.3 Ernst Ruska’s Second Assignment in 1930 1.4 Construction of the Primordial Electron Microscope 1.5 Ruska’s and Knoll’s First Joint Article 1.6 The Cranz Colloquium 1.7 Ruska’s and Knoll’s Second Article 1.8 The Role of Max Knoll 1.9 The Role of Ernst Ruska 2. Ernst Brüche and the AEG Research Institute 2.1 The Aeroplane Compass and the Aurora Borealis 2.2 Electron Optics 2.3 Brüche’s Electron Microscope 3. Reinhold Rüdenberg and Siemens 3.1 The Early Siemens Patents 3.2 Rüdenberg’s Source of Inspiration 3.3 Doubts 3.4 A Political Dimension 3.5 Prior Art 4. Léo Szilárd 5. Electron Optics in the USA and Great Britain 6. Conceiving the Idea: Summary and Conclusion Part 2. Materialising the Idea 7. Technische Hochschule 7.1 Bodo von Borries 7.2 Adolf Matthias

2 3 3 5 9 12 16 19 19 22 24 26 27 30 31 33 34 40 44 46 50 51 53 56 62 63 63 69

✶

This article represents two chapters from the draft doctoral thesis of the late John van Gorkom. See Appendix B. E-mail for correspondence: hawkes@cemes.fr.

Deceased.

Advances in Imaging and Electron Physics ISSN 1076-5670 https://doi.org/10.1016/bs.aiep.2018.01.001

© 2018 Elsevier Inc.

All rights reserved.

1

ARTICLE IN PRESS 2

J. van Gorkom et al.

7.3 Max Knoll 7.4 The de Broglie Wavelength 7.5 Interlude 7.6 The Rise of Nazism 7.7 Ernst Ruska—Left to Finish the Job 8. AEG Research Institute 9. Belgium 10. United States 11. France 12. Materialising the Idea: Summary and Conclusion Appendix A Siemens Patent List Appendix B Postscript: A Tribute to John van Gorkom by Dirk van Delft and Ton van Helvoort References

72 78 80 81 85 98 111 114 117 119 126 128 132

PART 1. CONCEIVING THE IDEA Just four years elapsed between Hans Busch’s publication of his lens theory (Busch, 1926, 1927) and the construction in 1931 of the very first device that could be called the primordial electron microscope. In these years, the concept of electron optics had caught the imagination of many according to Dennis Gabor, who told a British audience in 1942: “Busch’s paper was more than an eye-opener; it was almost like a spark in an explosive mixture. In 1927 the situation in physics was such, that nothing more than the words ‘electron lens’ were needed to start a real burst of creative activity” (Gabor, 1942).

And he added that for experimental physicists, “the words ‘electron lens’ were enough (. . . ) to ask themselves: ‘What can we do with electron lenses? Can we make electron microscopes, electron telescopes, etc.?”

Whether Gabor’s representation of the facts is altogether correct remains to be seen as will become clear later where the conception of the idea of an electron microscope in the period spanning approximately 1928 to early 1932 will be discussed extensively. The structure of this part is based on the existing priority claims with respect to the invention of the instrument.

Since Ernst Ruska received the 1986 Nobel Prize in Physics “for the design of the first electron microscope”, as the Nobel Committee formulated it, it seems fair to start with the story of the electrotechnical student Ruska and his tutor Max Knoll at the Berlin Technische Hochschule. The second section is dedicated to the claims by Ernst Brüche, who worked for AEG—the German sister company of General Electric. The third section deals with