1st International Seminar
on Recent Trends in Charged Particle Optics and Surface Physics Instrumentation

This year we tried to organise an international seminar on electron microscopy. It is very encouraging for us that all the invited people accepted our invitation so that on September 4 to 6, 1989 several world-renowned specialists in electron and ion microscopy and lithography met at our institute.

As an introduction, five-minute contributions were presented. They reported on the latest achievements of our Electron Optics Department and were later discussed more in detail at the individual laboratories.

Then lectures followed. They were given predominantly by our foreign guests:

Professor M. Troyon (France): The latest achievements in the field of field emission electron sources.
Ing. F. Pijper (The Netherlands): Coincidence spectroscopy in STEM.
Dr. L Veneklasen (Germany): Devices for electron microscopy and spectroscopy of surfaces.
Dr. B. Lencová (CSSR): A package of electron optical programs.
Professor K.H. Hermann (Germany): The projects in progress at the University in Tübingen (holography, lithography, and sources).
Professor A. Delong (CSSR): A 1:1 electron projector.

In the related discussions, which lasted even several hours, all the participants took part. The moderator was Professor Mulvey (England). He summed up the course of the seminar in his contribution "Final Comments". Marie Fojtíková translated it into Czech.

The extraordinary lively discussions have proved the importance and need to hold such seminars with international participation. We therefore believe we will succeed in organising next in the future.

I have been asked to give a brief review about what was discussed during the seminar. First let me talk about the contributions of the specialists from the Brno institution.

I have been impressed by the wide range of projects that are dealt with. Some have not been set going yet, they are in the stage of preparation, some are in a middle-advanced state, and further as, e.g., electron optical evaluations, reached an advanced stage of progress. It is also very interesting for me to follow the increasing volume of publications coming from the Brno institution. After all, it holds true for any kind of research that if you do not publish the results of your work, you had better throw them directly into a dustbin. Your colleagues will, most probably, not read them. I think however the outer world tends to judge an institution according to the number and quality of topical publications. I think it is a very good sign for your future publications that at your institution the number of computers grows as that of tulips. It also makes a deep impression on me that there has always been a solid basis of fundamental research work at this institute. For example, electron interference, which at the beginning seemed to be a technologically uninteresting field, became later - in the case of Fresnel bi-prism - very important for electron holography. If, at the beginning, no fundamental research is made, it is not possible to quickly reach the decisive stage of development. For example, as regards the metal-insulator-metal structures, we heard a very interesting lecture of Professor Delong and we saw an excellent demonstration in his laboratory. This is a case of a twenty-year old patent that suddenly becomes very important. Well, it is a very interesting situation - you have a mixture of projects: long-term, medium- term and novel ones that are of inspiration character. For example, the new table for electron lithography applies some innovated mechanical principles and in an inventive way makes use, with a remarkable simplicity, of friction gears. The whole project is very clever and illustrates the ability of the research workers to go to the utmost simplicity. This represents a great deal of hard intellectual work but no electron optical device will ever work at all if its utmost simplicity is not achieved. If you start to do something that looks quite simple, I think you have a certain chance that it will work.
Another thing I have the pleasure of is the co-operation with, for example, the Technical University in Clausthal that starts to develop. It is good for both sides to conduct this interactive dialogue. The same can be said about the co-operation of your institute and the Technical University in Delft. Perhaps every worker of your department learns or speaks Dutch so that there is really a very good international atmosphere here.
Now I return to the specialised lectures presented at the seminar. For many it must have been a serious shock to hear the questions asked by the critical auditorium. For example, Professor Troyon said that after such a short lecture he had never heard such a barrage of questions. The reason may be we are only a small grouping. However you can see there is something strange regarding his presentation and it is, for example, not clear if he succeeded in overcoming the second law of thermodynamics and if he is able to compress the electron beam into such a narrow region. I think, even after our discussions it is not clear what happens in his experiments but the results surely awake our interest. We all would like to know how the Troyon filter for the field emission gun really works. At the same time it reminds us of the fact that we must consider the whole field of energy filtration in electron spectroscopy more seriously than we did in the past. Professor Herrmann also mentioned that energy filtration is probably necessary for electron holography with atomic resolution. Dr. Veneklasen pointed out that also in low voltage electron microscopy we need a system to enable an analysis of energies. Dr. Svoboda recommended to build-in the energy filter into the design containing the phase plate made by electron lithography that is used for the correction of the aperture aberration of a transmission electron microscope. Energy filtration is thus an important topic that has emerged from our discussion. In the past, energy filtration was mainly a sport of a few enthusiasts. Maybe, further study of practical forms of energy filters will lead to commercially available high-quality units built in all types of electron microscopes.
I think that the contribution of Dr. Lencová regarding evaluations of electrical and magnetic fields and evaluations of trajectories was exhaustive. At the same time it illustrates the value of co-operation of two workplaces. If, for example, works were carried out only at this institute, it would be difficult to obtain very good graphics. In co-operation with the Technical University in Delft, to an excellent fundamental program an excellent program for the graphical output has been added whose author is Dr. Geurt who is very busy now. Using his graphical output, the program of Dr. Lencová is easier to apply for a number of people. If you have some unusual electron optical idea, you can use the graphics and very quickly obtain results. This means, it comes to elimination of the experimental work that was formerly inevitable. I also think the package of programs, which is now available in Delft, will considerably extend our possibilities. The next stage will be the extending of the available evaluations to field emission guns. If we have these evaluations at our disposal we will be able to simulate the Troyon system and to watch what is going on.
Professor Herrmann acquainted us in his lecture with a long-term project - with holography. Although the essence of the problem has already been solved there is still much work to do. It is very interesting that they decided for a 300 kV microscope in Tübingen. I believe they will be successful. Ruska did never believe that something like holography would ever work. Now, the device Ruska presented in his dissertation is constantly being improved. Many people believe they will succeed in presenting perfect holography. This would be very interesting because it is not any simple to achieve the goal using a 300 kV device. There are further problems Professor Hemnann mentioned. However people like Professor Hemnann leave in this field much work for any of you. You will never solve all problems in electron optics. You will always leave something for others. This is the reason why there are so many offers of work in this field to young people. In electron microscopy there is still much space for new ideas - in technology, processing, and understanding.
In research, competition - healthy competition - is very important. It is necessary to discuss problems. It was a very good idea to organise our seminar. There was not only the asking of questions, to some problems solutions were sought for. It is remarkable that the organisers collected all projects. The very old ones, which begin to be important now, the old ones, which have a very strong commercial future, and the, e.g. low voltage, ones.