Leon Heinen, Lukas Trippe, Leon Yeghiazarian
Scanning electron microscopes (SEM) allow the study of the tiniest objects. However, schools cannot afford scanning electron microscopes for school lessons. Therefore we want to develop a model of a scanning electron microscope for schools.
Scanning of an area with an electron beam can be most easily demonstrated using a cathode ray tube. On the other hand, you cannot put objects into a cathode ray tube and therefore you cannot use it for microscopy. To visualize the image formation, we started by building two models of a scanning photon microscope, where a laser scans across a three-dimensional object. A light dependent resistor (LDR) translates the scattered photons into electrical signals, which are processed by a computer to form an image.
Thereafter, we began building a model of a scanning electron microscope, where the object is scanned with an electron beam. We built an electron gun from a light bulb, however, the results were not satisfactory and therefore we bought an old Perrin tube on eBay and used its electron gun. For safety reasons, we were not allowed to use voltages above 5 kV and therefore we generated an electron beam with 250 V in vacuum, which we can steer across our samples using a magnetic field.
