Electron Microscope

[TheGoldSovereign]

Just wondering if anyone here has had experience using these, and especially for coins and errors?

I'm wondering what difference apart from magnification and depth of field there are compared to optical, there are a few images in different books using these setups. Years ago they would cost upwards of 1million, but now size and costs have come down.

https://www.phenom-world.com/desktop-scanning-electron-microscopes/phenom-pure

 

[terakris]

I've not used one of those but i do have a little usb microscope i used to inspect coins - got it off amazon. you can adjust the level of detail by getting closer to the coin, but here is a pic from a 1/10 britannia (so pretty small coin) showing a tiny red spot - this was probably 100-150x zoom or so i would guess:

[h103efa]

I've used one in the past, but definitely not for coins & errors, more like observing beta amyloid fibrils! I'used the multi-million pound Transmission electron instruments though! I know there are other types like scanning electron that are probably cheaper (tens of thousands)?

 

[Cornishfarmer]

Mate added microscope feature to my iPhone.   Press home button 3 times.   Surprised how good it is, can easily see the small date on the new £1 coins

[sovereignsteve]

I haven't used one for 40 years and in those days it was the size of a room and probably cost millions.

The images on the website gallery should give you an idea what it's capable of but they aren't that highly magnified. Should be ok for coins but no good for bacteriophages and viruses, which is what I was looking at.

As you say, there are some examples in Marsh and do help elucidate overdate errors etc.

How much are we talking about now?

[TheGoldSovereign]

So these large units are capable of upwards of 500,000x magnification! However I don't need these levels but the benefits are depth of field and ease of imaging as they come with computer, screen and software etc.

The unit I am looking at is the entry level, generation 5 at 150,000x magnification and 30 second vacuum time (needed to image, per sample). This retails at £53,000 but there are older generations that are ex-demo that I'm considering for less than a quarter of the price

@sovereignsteve as you said the ones year ago would fill a whole room, now they are bench top however still extremely expensive. But why do you feel they aren't any good for errors, do you think that's a case of technology having moving on now so that they could be useful?

I've spoken to the distributor and I'm looking to demo one to see what the outcome is, I will share some pictures from them when the time comes!

[sovereignsteve]

1 hour ago, sg86 said:

But why do you feel they aren't any good for errors

I didn't say that, in fact the opposite. The photos on the website would suggest they would give a good image of the surface of coins which is what you would need to elucidate overdates etc. High magnification isn't necessary, the images in Marsh are taken with a scanning microscope which I believe is the type you are looking at.

[TheGoldSovereign]

1 hour ago, sovereignsteve said:

I didn't say that, in fact the opposite. The photos on the website would suggest they would give a good image of the surface of coins which is what you would need to elucidate overdates etc. High magnification isn't necessary, the images in Marsh are taken with a scanning microscope which I believe is the type you are looking at.

There was something I saw in some book where the image sort of xrayed the coin, so you could clearly see what was originally punched? I thought it was this but I can't seem to find that image anymore.

Because of the DOF at this high magnification it does really help, with my microscope 1) I can't image in anywhere near the quality needed 2)When at higher magnification you can only see a tiny thickness of the coin, it's not very easy therefore to distinguish the letter/digit

[Murph]

Surely you won't need that high a magnification and you do get software to stack images and therefore increase your apparent DOF.

TBH I only ever use my stereo microscope for coins and rarely find myself going as high as 80x.  Altering the illumination (brightness and angle) also seems to help a lot.

X-ray crystallography/diffraction - don't  the smaller machines require you to powder your sample?  I don't know if I'd be happy having an x-ray source in my house for hobby use.

[TheGoldSovereign]

On 19/10/2018 at 03:12, Murph said:

Surely you won't need that high a magnification and you do get software to stack images and therefore increase your apparent DOF.

TBH I only ever use my stereo microscope for coins and rarely find myself going as high as 80x.  Altering the illumination (brightness and angle) also seems to help a lot.

X-ray crystallography/diffraction - don't  the smaller machines require you to powder your sample?  I don't know if I'd be happy having an x-ray source in my house for hobby use.

Yes more research has made me realise a high spec stereo may be better. Though my current is 90x and it's just not enough.

One with a motorised stage and software to automatically z-stack is what I need, but even with these the camera quality isn't great.

I guess the resolution is why people like Marsh did rent an SEM for certain errors

[Elements]

I use a x100 optical microscope on occasion. At such high magnifications the refractive index of air becomes a hindrance. Immersion oil ( to immerse the specimen and objective lens) helps.

It should wash off the coin no problem with acetone but risky with high value coins having any foreign contact

https://en.m.wikipedia.org/wiki/Oil_immersion

An SEM sounds like it would suit but certainly not a cheap option. And then there’s costs for service and repair etc. You could contact some local universities or private analytical facilities to see if you could use one on a pay per use basis?

[KevjustKev]

On ‎16‎/‎10‎/‎2018 at 16:03, sovereignsteve said:

I haven't used one for 40 years and in those days it was the size of a room and probably cost millions...

Not 40 years ago myself, nearer 30. Yet when I had to help shift a new one in to a different lab, my mate didn't take any notice of the warnings. Wiped all his cards! 

[Murph]

On 22/10/2018 at 07:00, Elements said:

I use a x100 optical microscope on occasion. At such high magnifications the refractive index of air becomes a hindrance. Immersion oil ( to immerse the specimen and objective lens) helps.

It should wash off the coin no problem with acetone but risky with high value coins having any foreign contact

https://en.m.wikipedia.org/wiki/Oil_immersion

An SEM sounds like it would suit but certainly not a cheap option. And then there’s costs for service and repair etc. You could contact some local universities or private analytical facilities to see if you could use one on a pay per use basis?

I take you mean a 100x objective with something like 10x eyepieces for a total of 1000x.

Isn't this a bit high for optical use on coins?  The depth and width of field and would be rather small, wouldn't it?

You do get objectives that use air or water immersion at or near 100x.  I can't say I've seen a water next to an oil to compare them.

 

I think I recall seeing older z stepper motors for some Wild Stereoscopes and I have seen some pretty fancy computerised controls on modern Zeiss scope adverts.

It sounds like you have your heart set on a SEM sg86.  Maybe you could find a University that have upgraded and decided to get rid of an older device?  I'd think that would be cheaper than buying from a dealer but then the support would be lacking in comparison.

[TheGoldSovereign]

On 24/10/2018 at 03:11, Murph said:

I take you mean a 100x objective with something like 10x eyepieces for a total of 1000x.

Isn't this a bit high for optical use on coins?  The depth and width of field and would be rather small, wouldn't it?

You do get objectives that use air or water immersion at or near 100x.  I can't say I've seen a water next to an oil to compare them.

 

I think I recall seeing older z stepper motors for some Wild Stereoscopes and I have seen some pretty fancy computerised controls on modern Zeiss scope adverts.

It sounds like you have your heart set on a SEM sg86.  Maybe you could find a University that have upgraded and decided to get rid of an older device?  I'd think that would be cheaper than buying from a dealer but then the support would be lacking in comparison.

Yes also assumed he meant 1000x not 100x. You are right about the DOF and this is why I was looking at a Zeiss optical with either a motorised stage or one that can be extended in the future. It's all about the software here to make the process of stacking easy, but I'm finding also the cameras for these scopes are 10 times the price just because they fit onto the unit!

100x is definitely not enough, this is what I have currently and you just can't see enough, look at this post which is as close and clear as I can get with my macro lens, and about the same as what I can see with my 90x stereoscope: 

SEMs are just too much, after having further discussions with the supplier these Phenom scopes are cheaper to buy but the same cost again to keep running every few years!

Hiring usage of one in a University or other site is an option, but I think turning up with, and trying to process 100s of sovereigns may get some funny reactions!

 

[Elements]

Yes just the objective was x100 I meant.

We occasionally get stuff from here, you find alsorts of second hand lab equipment and is often very cheap

https://www.labx.com/search?sw=Sem

Or here

https://www.go-dove.com/en/index