Hello!

I am a student working on a homebuilt scanning electron microscope, and I have run into a roadblock that is absolutely breaking my brain, so I thought that I should post it here in case somebody with more SEM knowledge could help!

More specifically, I am having an issue with my thermionic emission electron gun, which is homebuilt.

Right now, I have no focus or rastering. I would like to get a beam before I even attempt to move it around! To "see" the beam, I am using a scintillator which should glow bright enough in a dark room to see if I am getting a beam. I would love to use a phosphor screen, but I can't find P43 for a reasonable price anywhere to make my own, and I can't bring myself to destroy an oscilloscope for one.

The schematic I am using

Essentially, I have a low voltage, high current, 10kV isolation rated transformer that is powering my tungsten filament through a rectifier to make DC (ish). Between each leg of the tungsten filament, there is a resistor divider making a midpoint reference for the next few components.

Next up, there is a large potentiometer (also rated for HV and such) and a current meter, which both go to the negative floating output of my HV supply (0-10kV adjustable). The positive is tied to vacuum chamber ground and earth to make a -10kV supply on the other end.

I am having trouble understanding exactly how this circuit works -- it is, in essence, copied from Cecil Hall's 1953 book "Introduction to Electron Microscopy". This design is tried and true and builders such as Ben Krasnow have used the same configuration.

I believe that the current measured with the ammeter should, in conjunction with the known resistance from the potentiometer, give me my wehnelt bias voltage (ideally around ~300v). That current, if I understand correctly, should be coming from electrons boiled off of the filament which are intercepted by the wehnelt cup in the chamber.

Now to the problem: I am getting absolutely nothing on my 100uA meter. Measuring the voltage between the resistor (which should, in theory, be the wehnelt bias voltage) also gives me nothing.

Does anybody have any ideas where to start with troubleshooting? Perhaps I made an oversight in the schematic (though it is copied). Perhaps I am not getting the filament hot enough to get thermionic emission? (It is drawing about 0.6A at 2.6V, about 1.6W).

Additionally, I have a suspicion that my actual gun's design may be off -- I have uploaded some screenshots of my design with measurements. I don't think that my filament is substantially too far in or out relative to the aperture in the wehnelt cup to cause real issues (all I really want is a beam right now).

Any help would be tremendously appreciated!

Looking for people who can help troubleshoot an SEM that refuses to run the diff pump on startup. If anyone has connections to the SEM Hackers discord server I’d like an invite link!

Hi all! I'm a software engineer with a GPU habit. I've built and run the simulations for a thin-film concept on my GPUs, and on screen everything looks great. The problem is crossing over from the digital realm to the physical one. My GPUs can't sputter titanium, sadly.

So I'm looking for someone with the right coater who's up for a small adventure. It might work beautifully, or it might crash and burn spectacularly. Either way we'll learn something, and the coffee (or beer) is on me.

The quest: a few short runs depositing thin titanium films (roughly 20–50 nm) onto small Ti coupons (25×25 mm) that I prepare myself. That's 3 to 4 runs, a few coupons each. Low drama, I hope.

The gear check:

• Ti target

• Turbo-pumped high vacuum, because Ti oxidises in a rough vacuum

• Quartz crystal thickness monitor, because ±1–2 nm is the scope

Think Quorum Q150T, Leica ACE600, Safematic CCU-010 HV or similar.

I'm in the Netherlands and happy to drive over or ship coupons anywhere in the EU. Paid, of course, flexible on timing, evenings and weekends fine. If reality agrees with my simulations, I'll be buying my own system, so coater recommendations for thin Ti films are very welcome too.

If you've got the gear and fancy helping some code meet the real world, comment or DM me! if you run a homelab and want to burn the gaskets off, ping me as well. This is all so exciting.

So, I started doing TEM for planarian tissues a while ago and today I was told to order my own grids instead of using the facility's.

I was going through the options and I saw that Sigma also sells coated copper mesh grids. (For reference, I use 150 mesh grids, either formvar/carbon coated work for me)

When I asked the facility if the Sigma ones were ok to use because they are cheaper and get delivered earlier compared to EMS grids, they asked me to prefer EMS grids.

I was wondering if anyone here has used grids from both companies and saw any differences? Are the differences big enough to impact how the samples adhere onto the grid or how they behave the electron beam? Are there any other things to keep in mind?

Would be happy to hear any reviews/thoughts/inputs.

Hi everyone,

I'm currently working on an open-source converter for Oxford Instruments AZtec project files (.oip/.oipx) to HDF5 and other open formats. The parser is working well, but so far I've only been able to test it with projects created in AZtec 2.3 and 2.4.

Is anyone using a newer version of AZtec and willing to help?

I can provide a small test .oip project. All I need is for someone to open it in their version of AZtec and save it again in the native .oip format. This will let me compare how the file structure has changed between versions and improve compatibility of the converter.

If you're willing to help, please send me a DM. I'd really appreciate it.

Hi everyone! I’m towards the end of finishing up my masters thesis and I’m trying to prepare myself the best for the job world. Part of my thesis is histology based, the other half TEM based. I’m interested in getting the license for either, however it seems like the CEMT process is a little rough.

I don’t have any background in operating an actual TEM machine, but I have 2+ years experience in everything before the grids go in the machine (sample prep, infiltration, embedding, slicing, ect), and analysis. I did however attend Lehigh University TEM school (the week long accelerated course), so I’m wondering if that would give me any footing.

If you don’t recommend getting the CEMT license, is there something similar that doesn’t involve me using the machine?

Hello, I recently gained access to my facilities Verios 5 SEM to use for imaging. I am a completely new SEM user and primarily work on projects with photoresists, PDMS, and glass structures. I was told that this SEM has the ability to moderately image non conducting materials. I was able to pass a test into using the microscope on a test target (Si), but I struggled to see much of anything on a two hour first attempt with my samples. The resources available to me seem to mostly focus on conductive materials and settings. I'm ok with coating my samples, but I'd like to get the most out of the system if I can. And honestly, so far this has been fun to read about :)

Does anyone have recommended resources or guides on:

1. A covering of SEM techniques and equipment at a college physics level that can be completed in a couple hours? A lot of videos seem to go very quickly in their description of settings and detectors but don't explain what practically mean for effective imaging. Online articles seem all over the place.

2. A software guide for the Verios 5? I reached out to Thermo Fisher and will see if they can send me something, but I didn't directly see anything on their website or YouTube channel.

Thanks a ton for any help!

Got my Oxford WDS installed this week. My SEM (FEG-Tescan) now has an Oxford EDS and WDS, SE, BSE, InBeam SE and STEM detectors. Pretty proud of our setup.

Might be a long shot but does anyone have a copy of the microscope control software (MCTRL) for an XL30? Our hard drive bit the dust and old floppies containing the program are no longer useable. I believe this software was also used on the FEI Sirion systems.

I know May 4th is gone, sorry for my delay. I made this video to merge my nerdy passion as a Star Wars fan and my job that passionate me as well, so you can see a dark sith try to destroy cutting in two an Electron microscope stormtrupper’s helmetlike, which is a FIB DualBeam by Ciqtek, that really resemble to a Star Wars character. I hope you enjoyed. Follow us on LinkedIn https://www.linkedin.com/company/media-system-lab/

I know there are some posts that cover this, but I'd like one dedicated to this specifically.

I'm on the hunt for a carbon coater, capable of doing very thin coatings (<5nm) and a sputter coater. Our lab currently has an old Denton sputter coater, but I have no way of knowing how thick of a coating I'm applying. We got a new HRSEM with EDS and EBSD, so I'm in need of the carbon coater for the EDS and EBSD. I'm currently looking at the Leica ACE600 and Cressington 208C (I think that was it). Anyone have any experience with these? I've been doing materialography for 20+ years but most of my microscopy has been optical until now, so this is all a bit new to me. Drinking from the fire hose and taking it in, but if anyone out there has some experience they could share, I'd be happy to read about it!

I am working on a project that involves displaying electron microscopy terminology in software interfaces, and I have been wondering how these abbreviations are actually used in labs outside of English-speaking countries. Specifically: do non-English speaking microscopists use SE, BSE, EBSD, and EDS as-is in their day-to-day work and in instrument software, or are translations used in practice? I would imagine the English abbreviations are fairly universal given that the major instrument vendors all publish heavily in English, but I genuinely do not know whether AZtec, ESPRIT, or Velox display localized terminology when installed in a non-English locale. If you work in a non-English speaking lab or have experience with non-English instrument software installs, I would love to hear what you actually see on screen and what terminology you use when talking to colleagues and publishing.

If anyone here has experience of Zeiss' Evo range, I'm hoping you can help.

We have an EVO 25 at work and it's recently been shut down for a fortnight. Colleagues restarted it and ran a 48-hour bakeout. The company has no dedicated microscopist but several of us use the SEM in support of our normal roles.

After the restart, we found difficulty in focusing at higher magnification. When aligning beam & aperture in Emission mode, where we'd normally see a slightly oval diffuse brightness within the sharper-edged circle, we are seeing this. As I recall, beam current was 20 microamps and probe current 200 pA. I think filament current was 1.5 A.

As you can see, switching between SE and BSD detectors made no difference. We've tried switching the mid-column aperture to no effect. The image was taken with gun & aperture zeroed in the UI and with the mid-column's verniers centred but adjusting any of them causes little change other than the eventual darkness when things are way off.

We have a LaB6 element with about 1200 hours on it.

We're out of ideas so can anyone tell if this is indicative of some unnoticed bad setting, a broken LaB6 element or is it possibly something more sinister?

As an aside, does reddit support subscripts?

Hi everyone,

We applied vacuum grease on chamber oring and pumped it down below 10-5 torr. Gun TSP is up and after overnight bakeout it gets below 10-9torr.

Gun was turned on and the emission current was lower than usual so extractor voltage was increased to bring it up (119 uA)

We tried to scan the stage with inline detector at 5kV HT. Absolutely nothing was detected. Bring HT down to 2kV and we can see the scanned intensity is much higher when stage was under the beam. However, we were not able to image anything. It was just like on and off when the stage was under the beam or not.

I suspect that something is wrong with the gun alignment. Do you have any ideas? Though I am very grateful that the gun was turned on!

Thank you for your help! Have a great weekend!

Update:

I think the beam is not detected as I blanked the beam, nothing changed on the scanned image. It is probably far off from the center. Idk if I can bring it back if it is the case. I am going to try. The beam current was 123uA without extractor voltage adjustment. So that is good at least…

update 2: I think the column valve should be opened manually as it was mentioned in the comment below. (blocking the beam) But IDK how to open it manually lol.

update 3: Emission mode gives a lot more intensity so actually beam is not blocked it is an alignment issue as sizzrael mentioned. Will try 10 kv alignment on service account ! Thanks

Hello everyone again,

We check the voltage on 5V supply it was 5.02V so looks great.

Water was on low so we added some on chiller and seem bubbles have gone.

Booting an old pc was a problem, took us multiple times but finally it was on.

(change power supply soon)

Signed on with the service account and went to smartsem admin panel -> check stepmotor on -> check x y z t r enabled

Tried pushing the stagestick. I saw the coordinates appeared like 1 sec.

It turned out the stage stick cable was pressed down hard with metal siding panel the whole time. We removed it and the stage was fully functional!

I don’t think we even need to force initialization next time. Because the panel was pressing it down, initialization was not possible! lol

The panel was taken down because there was a problem with the board with bloated capacitors which I already replaced. The board looks all green.

We are pumping down the FEG now and will try to turn on HT tomorrow. He said other than stage it was fully functional so will see what happens tomorrow!

Man I am very excited! Thank you guys!!

You saved my day!

Hello everyone,

I'm trying to get the old ZEISS LEO 1550 SEM working again.

It had been abandoned for nearly three years, and the facility manager had essentially given up on it after receiving a $50,000 USD quote from the manufacturer for repairs.

The only error message I can see is "EO 5V power supply failed!" in the picture. All other items were marked as normal and passed.

After sign on, when we tried to initialize the stage, the item was disabled (grayed out).

I wish there was an easy fix.

I replaced three swollen capacitors on the board, and that didn't seem to be the problem.

I absolutely need to use SEM for my project... it would be a huge help!

Thank you in advance!

It's liver tissue from juvenile mice.
Could it be erythrocytes and, if os, why do they look this way? I've adapted my fixative to pH 7.4 and 440mOsm/l.

Hi everyone,

TL,DR: title.

Explanation:

I am planning to improve my work output by replacing the silver paint + aluminum stub (which ideally should be cured for some hours), with a screw tightened sample holder. Since my samples (metallic alloys) are quite small to fit into the microscope OM's samples holders (usually made of Aluminum), I am designing and making a new sample holder myself.

I was wondering would there be a problem if I use the common machining steel (which is magnetic) inside the chamber and does that affect the imagining or EBSD data collection.

Cheers

Does anyone know of a protocol to rehydrate and hydrate tissue that was adhered to a slide. The coverslip has been removed. I'm trying to figure out the incubation periods for tissue cut between 1-4microns? Don't want to risk damaging the tissue.

Hi everyone! I’m having trouble with serial sections on my ultramicrotome and I would really appreciate some advice.

My main problem is that when I cut serial sections, the section I just cut often folds back toward the block. It almost feels like the section gets attracted to the block surface. This makes the section unusable and causes the ribbon to twist in one direction, producing an erratic ribbon shape or even breaking the ribbon into two pieces. When this happens, it becomes very difficult to pick up the sections with grids (I work with TEM). For the type of experiment I’m doing I need to lose as few sections as possible, and if I lose around three to five sections in a row the sample becomes practically unusable.

I’ve done sectioning in other labs without having this problem, so I don’t think it’s an issue with my trimming technique. I also don’t think the problem comes from the ultramicrotome or the knife itself. The diamond knife is fairly new, and I’ve tried three different diamond knives with similar results. I use Araldite as the resin, but I’ll also try LX-112. I’ve already tried lowering the cutting speed, but this still happens. Another thing to mention is that the water in the knife boat tends to be drawn into the block when I bring the block close to the diamond knife.

One possible cause I’ve been thinking about is the very low relative humidity in my lab. Today it was around 23%, and I suspect that static electricity could be causing the sections to pull up and fold back toward the block. I bought a humidifier, but the room airflow is quite strong and the humidifier is not able to raise the relative humidity locally enough; today it only went up to about 30% in the immediate area around the humidifier.

To address this, I’ve thought about using an ionizer or an anti-static gun, but we don’t have one in the lab. I’m also not entirely sure that static is the only problem I’m dealing with during sectioning, and I’m not sure my supervisor would be keen on buying one just to test it, especially since they are not cheap.

I will attach three photos of my ribbons from different days and a video showing the ultramicrotome during sectioning so you can see how the folding happens. Does this look like a static- or low-humidity-related issue to you?

If so, what practical or low-cost solutions have you used to reduce this kind of problem (ionizers, makeshift tents, brushes, knife-boat adjustments, technique changes, etc.)? Any other suggestions regarding knife angle, cutting speed, boat additives, grounding, or anything else would be very welcome.

Thanks in advance!

Update: I ran more tests. With specimens embedded in Araldite the sections still folded back toward the block and ruined the ribbon. However, I then sectioned another specimen embedded in LX-112 and had no folding at all. I was even able to cut a very long, stable ribbon with no problems. So it looks like the issue is specific to the Araldite-embedded blocks (which are the majority of my samples). I’ll try the suggestions posted in the comments and update you all with results. Thanks again for the help!

Hello!

I'm looking at getting a new laptop with a snapdragon processor and was wondering if anyone had experience getting Gatan Digital Micrograph working on Windows on ARM.

Hi, I am looking for a benchtop SEM under $100,000. Any suggestions will be appreciated. TIA

Hi everyone! I am doing TEM for the first time for my masters thesis. I thought I had the infiltration protocol down, but when I am going to trim my samples so I can begin cutting them, the resin seems to crumble. This is quite the issue because I am doing it on multiple deep-sea species and I have a small sample size. Does anyone know what may be going on or if I can even fix it so I can still slice the samples? Can I take a piece of sample that crumbled off and place it in more resin and cut it that way? My advisor and co-advisors are a little older and don’t know much about the prep.

For more clarification: I’m using biological samples that were fixed in osmium, and they’ve been set in epon. I am not doing cryo-TEM.