DL123 - SEM Teardown Part 2: Electron Gun & Column
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- เผยแพร่เมื่อ 21 ก.ย. 2024
- Continuing the teardown of the Hitachi S800 Scanning Electron Microscope. I take apart the main column assembly containing the field-effect electron gun and focusing & sigmatism correction coils.
/ dexterslab2013
dexterslab2013....
/ dexterslab2013
nice, pls tear down the latest electron microscope.
Regarding the emitter: Hitachi is using the term "Field Emission" for Schottky emitters too, i.e. emitters that are heated and under high extraction voltage at the same time, so it's not sure that the emitter is cold.
The emitter for the S800 is cold. I own an S4000 which is similar.
The coil at 27:37 is the main focusing lens. The objective lens is basically in the tip of the cone on the very end. The large magnet is the condenser lens. While the condenser does look about right, I always thought that the focusing lens would have been bigger and require more current. But perhaps it doesn't as its really just preparing the beam for the primary objective. I also would have thought that the astigmatism/bending lenses (the octopole) would have had iron or steel cores. But hey, you learn something everyday. My experience with this stuff is mostly limited to high current ion beams for semiconductor processing. Thanks for the video.
I don't think so. The 1st set is a saddle deflector that probably aligns the beam to the center of the aperture or the center of the objective. The larger coil is a condenser, while the objective was left on the chamber (you can see it at the chamber on the 1st video)
I wonder if the electrode on the beam aperture doohicky is so you can get the beam dead centre though the hole - adjust for minimum current hitting the aperture
i think that could be entirely possible, i only have a couple of basic block diagrams for this machine but newer models used an alignment target that would generate a pattern to view on the monitors.
I have not seen that mentioned in the manual of the microscope. At least on mine the apertures are for different tasks, On mine the apertures are 400µm 300µm 200µm 100µm where the first 2 are noted to be for X-Ray analysis, and the second 2 are for secondary electron imaging.
I can probably tell you guys more, once i get mine up and running.
edit:
Oh and thanks Dexter for the tairdown, it has helped me on the restoration of my microscope.
edit2:
The manual dose mention the aperture control in the condenser lens alignment procedure, but it dose not state it is the thing being aligned. Im guessing the condenser lens has more then 1 coil for alignment, alternatively i can guess that the scanning coils might be able to do so as well.
wonderful !!!! brilliant video. I wished I had something like that for a teardown video
27:40 looks like a deflection coil. Maybe?
I'm always very concerned if it comes to ceramic parts. Beryllium Oxide. You can never know. Take care!
yea it's for sure a deflection coil of some sorts but if you notice there are only two coils which means it has only one axis so i though it was a bit odd compared to the stigmatism coils. I doubt there is any BeO in there as it's normally used to transfer heat and be an electrical insulator.
Thanks Max, go and visit your scrap and recycling centres and get them to put interesting things to one side for you! You never know you might get something unusual!
There is no chance to get stuff from recycling centres, due to legal issues here in my country. They even denied my offer to pay for scrap. They said they are allowed to sell to recycling companies only.
(I was planning to open up a recycling business though. Again, too many legal issues)
man that top cap certainly wasnt going to fall off. i guess the designer decided to keep going until he ran out of room for more nuts.
yes there is a slight possibility of over engineering in that area!
Great video, thanks for posting. I think the plating on those internal components may be nickel, making it seem magnetic, also, the additional coils beside the main focusing magnet may be to do with astigmatism correction or 'vernier' adjustments for beam positioning or focus perhaps, but that's just a hunch.
thank Dan, it's hard to tell as everything is so bright without any oxidisation on the metals.
@DextersTechLab if you still alive, can you remember, how actually the moving part at 17:34 looked from the bottom. I wonder how the seal is achieved. Was a metallic ball or smth else? btw we have this kind of hitachi s800 still working here.
Hmm, i think it was covered in some rubbery gasket material. If you seal off the column and open the chamber this would naturally be sealed shut by atmospheric pressure
Nice Video ! I am preparing to refurbrish an identical unit (e-mailed you a while ago), so this tear down will save me a lot of time.
The coils you took apart were the condenser coil (the big one) and the stigmator coil (not 100% sure). Since this is a cold field emission gun unit, electrons are pulled from a ninute tip of the filament (100 nanometer or so). As the tip gets covered by atoms of air, the emission gets quite instable, which negatively affects image quality. The apertre strip you took apart is used to measure the momentary emission current (a metal box cotaining an opamp was used for it). This data is used by the imaging system (based on a Motorola 6800 8-bit CPU) to compensates for fluctuations in emission to improve the image quality.
Thanks! I have your email, i am saving all the parts you need, when i am finished i'll detail them all for you. If you see anything else you need, just let me know.
How amusing, im also preparing to refurbish (and rebuild part of) an identical microscope. Maybe we can help each other out in problem solving in the future.
Im guessing though, that your microscope is in better condition then mine, seeing as every cable between the column and the console has been cut. And im missing the ion pump power supply (though i can rebuild that from the schematics if i cant track down the original).
Im also planning on creating a digitization card for the microscope, to allow the analog output to be saved digitally. So far the plan is to stick it into the consoles expansion bay, and connect it to a computer that is outside of the console.
hi ! Great news ! I am currently on holidays but will gladly share infos ! I was able to find the schematic diagram for the scope and some instructions from a university for the S-900 model (very similar). I will try to send some videos and get in contact with you when I get bach home (mid july).
If you are in need of the schematics of the S800, i have a full copy of them (in book form), as well as the original owners manual. And am currently tracking down the service manual.
Also, great news that you responded as well, i look forward to working with you in restoring our 2 microscopes back to working order.
edit:
Also, have a nice vacation / holiday (not sure what to call it).
WOW - that would be great ! I will contact you in two weeks !
Such beautiful engineering. I would never be able to throw that away but the pneumatic actuator is about the only thing I can think of uses for, except, Hmm, I wonder if the large coil would be any use for flinging ball bearings.
Wondering if the smaller set of coils were some sort of deflection control for fine beam positioning?
yes i don't think there's much to reuse inside the column, most of the reusable stuff is in the vacuum system. It is beautiful yes, i need to find or make some ornamental use out of the column parts!
You would not happen to still have a spare 20l ion pump? One in my s800 died. Also is the column still avalible?
Im very close to getting a s800 running. Just have a uhv leak and broken ion pump and powersupply to deal with
Sorry no, it was all sold/given away within a couple of weeks after making the video.
@@DextersTechLab well, thats unfortunate. thanks anyways.
Are there any markings on the copper gaskets? What is that speckled graphite, zink-like coating on some of the parts? Do you think the needle from a gramophone could substitute the cathode?
And thanks for doing this!
There are no markings on the gaskets, the pattern on some of the parts looks very much like zinc so at this point i would say it is zinc. I doubt a gramophone needle would be suitable, most home made SEMs would use a hot cathode & thermionic emission.
клевая железка!
I'm sure the "proper procedure" doesn't involve a sledge hammer either. ;)
What is the electron column made of?
Pretty sure this is the nuke from Stargate? lol
omg i had better be careful!!
Can someone please send me a link to Part 1
Found it!! THX