After reconstruction, the laboratories of the Institute of Materials Science and Engineering shine with novelty. In one of the labs you can find a piece of technology that immediately attracts your attention due to its historical appearance. It is no wonder, this "grandfather" among electron microscopes is going to celebrate his fiftieth birthday next year. And the microscope is still working, although today not in research, but in teaching.
This historical Tesla-branded beauty is actually the so-called transmission electron microscope. This type is also called a radiation microscope, because in this case electrons pass through the examined sample and are subsequently detected by a sensor. With a transmission electron microscope, it is therefore necessary to use super thin samples and high energies so that electrons can pass through the object.
"Specifically, it is a Tesla BS-540 transmission electron microscope. It was installed on November 1st 1974 at the then Department of Material Science in a university building in the center of Brno, as at that time the current university campus did not exist," recalls Professor Tomáš Podrábský, who at that time worked and still works at the Institute of Materials Science and Engineering of the Faculty of Mechanical Engineering of BUT. His further career was closely related to this device as he was the only employee working with it.
Tesla Brno, which made Czechoslovakia famous around the world with its electron microscopes, as well as the Institute of Scientific Instruments of the Czechoslovak Academy of Sciences and, of course, the leading personalities in this field: professors Armin Delong and Vladimír Drahoš – they all participated in its design and development.
The metallurgical microscope was part of the BS-500 series that Tesla manufactured. It has an accelerating voltage of 80 and 120 kilovolts, and following its installation, its resolution was experimentally measured at that time an incredible 0.7 nanometers, which made it the state-of-the-art device of its period. The microscope was also equipped with a goniometric workbench that was used to precisely rotate an object around a fixed point in space. The institute also purchased an adapter for liquid nitrogen cooling, which prevented contamination of the samples.
The microscope cost 519,688 Czechoslovak crowns, which may not seem much. However, in the seventies, the average wage was around two and a half thousand crowns and the basic version of the Trabant car cost 36,500 crowns in 1978. Half a million for a microscope was certainly not a negligible amount even for the university of that time. "It was acquired using investments that were specially allocated to our department for this purpose, and its acquisition was then undertaken by Professor Eduard Dorazil, the Head of the Department" Podrábský explains.
"In its time, it was the best electron microscope that was produced in Czechoslovakia. It is still used to day in some research institutes, for example in Slovakia. At our institute, substructures of samples of alloys of iron-aluminum based metals were examined within the framework of the Government research tasks, today we would say projects. Thanks to the research on the device, several patents were created and, of course, countless final theses – there could have been hundreds of them. But it was also important for practice, we provided measuring for a number of industrial companies and production plants," Podrábský describes.
Of course, the device did not generate digital images, as is the case today, so the laboratory had to be equipped with a classic darkroom for developing photos. What has not changed even after half a century is the color. Today, as then, they are black and white. The electron microscope does not work with light, but with electrons. Unlike the light, the electrons are monochromatic, in other words, they have a single wave length for a certain acceleration voltage, so all images are in shades of gray and can only be colored afterwards.
The device of the Institute of Materials Sciences was used in research until 2014 and is still operational, but today it serves only for demonstration to students. "It's great for me to be able to disassemble it and show students the cathode, the anode, the capacitors,... They can learn to prepare samples, which used to be prepared manually – and the sample was up to 300 nanometers thick. Now, of course, the technology is much more advanced, but it is still important to show students what today's devices started from," adds Podrábský, adding that it is good that Brno is proud of electron microscopy. "Not long ago, Czech TV’s Hyde Park of Civilization show welcomed Richard Henderson, a winner of the Nobel Prize in chemistry. And he said, to paraphrase him, that if he were to advise young people who want to specialize in this field where to study these days, he would say: Go to Brno," Podrábský concludes.