DIY Scanning Electron Microscope - Operation procedure--- make money online

After getting back from Maker Faire (which is always a hugely enjoyable and inspiring event), I thought that my microscope might need some repairs.  As it turned out, I only had to change the filament and tighten some screws that came loose during the trip back from the Faire.  The microscope works just as well as it ever has -- I didn't even need to move my alignment magnets.  I made this video to show everyone what using it is really like.

Also, if you haven't been able to attend Maker Faire yet, it really is as amazing and epic as you have heard.  The intelligent and inspiring people who make it happen are a large part of the motivation that I had to build and display this microscope.  In turn, I hope my project inspires others to create things and share their ideas with everyone.  There's no better way to have fun and celebrate accomplishment at the same time!

hey everyone I realized that I never

made a video showing me actually using

the scanning electron microscope so I

was actually really surprised that this

thing works after getting it back from

Maker Faire it took a couple of hard

knocks during the trip so I changed the

filament and tested it out and yeah it

still works so let me show you how I do

it so the water chiller is already

running this is just pumping some

automotive antifreeze through the baffle

that sits between the diffusion pump and

the vacuum chamber that just keeps

diffusion pump oil from getting up into

the chamber so that's already running

the first step is to load a sample into

the microscope and today I'm going to be

looking at a small piece of copper mesh

it's a very fine screen and the sample

goes inside here so I already have it

loaded in so let me just zoom in there

so you can see it so there's that copper

mesh that's sitting on the platform

inside there and that's where the sample

is okay so now I'm going to place the

bell jar over the whole microscope and

I've got an arrow that indicates where

this bell jar needs to line up just so

that all my alignment magnets are in the

right place this is all in the same spot

okay and now I'm going to turn on the

mechanical pump and use this little plug

here to seal off my vent valve so

there's air is being pumped out of the

chamber now and on the first of the

three vacuum gauge is the one that

indicates the highest pressures get this

copper out of the way you can see the

needle starting to come down so this

will take five to ten minutes to get to

a vacuum where that mechanical gage

can't read any more so I will see you in

five to 10 minutes the roughing pump has

gotten most of the air out of the

chamber so now I'm going to turn on this

thermocouple gage

and make sure that the pressure is low

enough to start the diffusion pump got

to change that battery oh come on you

can give us a reading

well whatever trust me it's low enough

it's about 300 millet or in the chamber

now so I'm going to switch on the

diffusion pump and it's cooling fan and

also turn on the pen engage it's much

easier to get the pen engage started

when the pressure is still about 300

millet or rather than try to start it

after the diffusion pump has done its

work so the diffusion pump will take 15

to 20 minutes so you get the chamber

pressure down to operating pressure

which is about 10 to the minus 4 so I'm

going to stop the video and start again

in about 15 or 20 minutes the penning

gage is now reading 2 times 10 to the

minus 4 millibar which is pretty close

to 2 times 10 to the negative 4 Torr so

that's good enough so I'm going to

switch this off to avoid causing

interference later and let me pull the

camera back so the next step is to put

the light tight shroud on the microscope

that's what we're going to be doing is

light-sensitive so I'm going to put this

this is coroplast just black plastic to

cover that up and now we can start

switching it on so first I'm going to

turn on the high voltage supply the main

high voltage supply let that warm up for

just a few seconds

okay now I'm going to switch the

high-voltage on Brad about three

kilovolts and now I'm going to turn the

filament on okay good we're registering

about 50 micro amps of emission current

which is good that means that the

filament system is working the way it

should

next I'm going to get the

photomultiplier power supply ready this

has sort of like a preheat it's all tube

based so turn this on first and there's

like a relay that clicks after 30

seconds and then we can switch the high

voltage for that on in the meantime I'm

going to turn on the scintillator

voltage okay a little bit of arcing

there always a good sign and I'm going

to turn on the focus voltage

we still have 50 micro amps of emission

current which is good that means that

that arcing didn't kill anything this

microscope sometimes arcs that's just

the way it is I'm going to turn on the

photomultiplier supply voltage and we

now have an image on the mic on the

oscilloscope so let me turn off the room

lights

and there's our metal mesh screen so the

controls on the oscilloscope I don't

really need to use I'm just going to

turn the dials on the front of the

microscope to change the scan pattern so

if I hand the scan around you can

actually move around in space inside

there and get a different different view

of the screen the screen itself is a

really good target because it has the

same pattern all over the place so no

matter where the scan hits the sample

we're bound to get a nice pattern like

this and it's also square so that you

know if the image looks like this I'll

know that the amplification and either

axis doesn't match so I can adjust that

so that we get a nice clean image and

then we can also try playing with the

photomultiplier voltage to get a little

bit of a better image maybe turn up the

scintillator voltage a little and we can

adjust the gain on the photomultiplier

amplifier oops well too much there

so there you have it let's actually

let's change the zoom level so the

easiest way to change the zoom level one

we can change the scan pattern so by

doing this we sort of zoomed out and

readjust the focus to zoom in a little

bit more we can make the scan pattern

smaller but what we can also do is

increase the acceleration voltage and by

doing that the scan pattern becomes

smaller because the electrons are not as

easily deflected by the plate so I'm

going to up it a couple clicks here so

we are at four kilovolts now it's to

another five hundred at four and a half

kilo volts

as you can see it's kind of a big

balancing act between getting all the

knobs in just the right spot change the

scan pattern again so we're in pretty

close now

I'll do some measurements on that copper

mesh screen so that we can kind of get

an idea of how close we are sitting pan

around a little bit

so you can actually see the weave

pattern of the mesh so this this wire is

going on top and this wire is going

underneath so it's woven like a fabric

and there's still some residual noise in

the image there's kind of this nice wavy

pattern here but we're at pretty high

magnification so you can go a little bit

higher

up to five kilovolts acceleration now

as you can see that's getting near the

resolution limit I mean we can kind of

see some dark spots on the screen which

indicates maybe some dirt like oil or

something that's charging up so those

weird looking areas even though the

screen is all metal if there's a film of

oil on the screen and the oil becomes

charged that means that the electron

emission from that area is going to be a

little bit weird okay there was that arc

again as you can see it temporarily

causes the image to disappear probably

because the photomultiplier became

saturated but luckily it came back so

you can get an idea of how delicate and

shaky operating this microscope really

is it works all right I mean we've got

an image here oh it's let's zoom back

out but as you can see it's definitely

interesting just for for exploring the

design of electron microscopes I really

don't think that this thing in its

current form could be used you know for

any actual research but that's where you

guys come in we're going to write some

documentation for this thing and maybe

make another version okay see you next

time bye

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