I used to have access to some pretty nice Scanning Electron Microscopes (a SEM) at my day job. While they are a bit more complex than a 3D printer, they are awfully handy when you need them. [Adam Guilmet] acquired a scrapped unit and started trying to figure out how to breathe life into it. His realization was that a SEM isn’t all that complicated by today’s standards. So he has set out to take what he has learned and build one from scrap.
In all fairness, he has a long way to go and is looking for help. He currently says, “[T]his is being powered by fairy dust, unicorn farts, and a budget that would make the poorest of students look like Donald Trump.” Still, he’s collected a lot of interesting data and we hope he can build a team that can succeed.
One problem is that generating, focusing, and detecting electrons is probably the easy part. The hard parts are drawing a very heavy vacuum, the need to do things like gold-coat insulating samples (we used to put ours in an argon chamber and sputter gold on the sample; a gold-coated die in a plastic keychain always made a good gift). You also need high voltages, and to be careful of energetic electrons striking things and producing X-rays that aren’t good for you.
Then there are the other things you’d like to have once you have a SEM. EDS (Energy-dispersive X-ray spectroscopy) and Auger spectrometry come to mind. Another interesting use is to collect secondary electrons emitted from a CPU running a loop. If you collect the emissions at the same point in the loop long enough, you can determine if that area of the device has a positive or negative charge (that is, a one or a zero). Scan the beam in the XY axis and you can build a picture of the electrical state of the device. Repeat that at different points in the loop and you can build a movie and watch bits travel across the CPU circuitry. Sounds like a fantasy, but it has been done–but not in someone’s garage. At least not yet.