Construction of a REM Model

Maurice Wald, Florian Büttner

project report

Scanning electron microscopes (SEM) are of major importance as they can image nanoscale objects. However, electron microscopy cannot be performed at schools as these instruments are far too expensive for schools.

Our goal is to build a model of a scanning electron microscope for schools to help students understand how this important instrument works.

For our first model we used photons instead of electrons, i.e. we used a laser pointer instead of an electron gun. The model consisted of the laser pointer and a light dependent resistor (LDR) inside a drainpipe and the "atomic surface" consisting of small plastic spheres was scanned using the laser beam. By inserting the voltage values from the LDR-circuit into an Excel table, we generated a simple 3D-image of the scanned surface.

In order to realize an SEM with a real electron beam, we attempted to build a simple electron gun ourselves, however, we faced numerous problems in our initial experiments. As we were not able to focus our electron beam, we decided to use the electron gun of an old monitor.

We hope to get closer to our goal of building a realistic model of a SEM at low cost by improving our vacuum and optimizing our apparatus.

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