Turning up the electron beam on a Philips CM10 Transmission Electron Microscope

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Turning up the beam on a Philip's CM10 Transmission Electron Microscope and getting it centered with the electron optics and apertures.

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So, I have been so busy with work and projects that I have been unable to work on the EM420 . To make up for it I recorded a short video of me turning up the filament, centering the Condenser 2 aperture and filament and some Condenser Stigmation. and If you are new to my blog you can follow this link to the first post on the subject.

Reviving a Vintage Transmission Electron Microscope

As you watch the video, you can refer to my explanation in another window.

First off, I have already turned on the High Tension, it is only at 60kV because this scope has been down for a while, and I like to turn it up to maximum, which in this case is 100kV, gradually. Times are approximate.

0:00 to 0:10 Turning up the filament, every thing is dark the first few seconds because the filament needs enough current for it to get hot enough for the electrons "evaporate" out. They then travel down through the column and hit the Phosphor Screen transducer that I am videoing from through a lead glass viewing window on the side.

0:11 to 0:30 Saturating the filament. Carefully getting it as bright as possible. I prefer to do this at around 8,000 to 10,000X depending on the TEM.

0:31 to 1:44 Here I am centering the C2 aperture, mechanically. This is done by turning the intensity up and down across an inflection point and adjust two Axis on the mechanism until the spot is equal over the crossover point. Basically overlaps equally. This usually takes the longest.

1:45 to 3:29 It is hard to see here but I am centering the gun coils, they guide the beam down the top half of the column through C1 and C2 onto the Specimen. At 2:06 you can see the "Cats Eye" or called "Gods Eye", I basically want that eye centered, within the beam and the screen. The default photo for this post is an alright screen shot if it. There are several coils in the gun section that I can adjust to center it. I want to note that the Cats Eye is only visible when the filament is below saturation, which is the point the filament is its brightest. On this scope it appears a few clicks of the filament knob down. This whole process is something you really need someone to walk you through in person first time, but this video may come in handy for someone who is rusty or learning.
At 2:50 ish there is some more nice moments where you can see the eye clearly.

3:30 to 4:00 You will notice here that the spot is being stretched and squished. I want to get the spot nice and round. The Condenser stigmator coils enable me to do this. I am also adjusting the intensity, and therefore the size of the beam. Adjusting the size helps me see the distortion. Unfortunately from the perspective of the camera, which is viewing off the side of the screen it will appear oval even when it is round.

4:01 to the End. I run through the whole process all over again (with exception of turning up filament). Basically fine tune everything. Lastly, I saturate the filament and the Cats Eye disappears. The Cats Eye is a phenomenon of the filament structure, which in this case is Tungsten. I have attached a picture of a Lanthanum Hexaboride filament which looks similar. This one in particular is useless because it cracked, so it just hangs out on my desk. The electrons are emitted right from the tip, where the two fine wires meet at the purple crystal. Tungsten looks the same, except its just a wire loop.