
DIY Scanning Electron Microscope - poindontcare
http://hackaday.com/2011/03/23/diy-scanning-electron-microscope/
======
bkraz
I built this electron microscope. Let me know if you have any questions.

~~~
ChuckMcM
About a zillion :-) Building one has been one of my "wouldn't it be neat to do
..." projects for a long time.

Can you say a bit more about the lenses? The Heathkit oscilloscope I built as
a kid had electrostatic plates that were used to focus the beam rather than
anything lens like.

Have you considered using bits of lead type as your test target, they have the
advantage of being asymmetric and recognizable, could help with linearity
measurements.

The SEM I used at Intel a couple of times had the electrons coming in at an
angle and the detector at an angle. have you considered something like that to
improve the signal pickup of your optical tube?

~~~
bkraz
Most commercial SEMs use electromagnetic lenses because they provide higher
power (more drastically change the path of electrons) in a smaller space. The
problem is that they require custom iron pole pieces. It's easier to build
electroststatic lenses, which are just metal conductors and the geometry is
not extremely critical. Search for Einzel lens for details. The condenser and
objective lens in my scope are Einzel lenses made from copper pipe from the
hardware store. I like the idea of looking at lead type with the SEM!

The angle of the incoming electrons toward the specimen is what creates the
viewing angle in the image. The angle of the secondary electron detector is
what creates the apparent illumination direction. It's true that setting the
specimen to split the beam and detector angles will provide a good image,
similar to having a good key light in photography.

