Electron microscope slow-motion video of vinyl LP

ever since setting up this electron microscope in my shop I've wanted to make animations with it showing video taken through the microscope and I've also been thinking about different recording media lately so I put the two together this weekend and came up with this this is an animation that shows a phonograph needle riding in an LP groove so in this video I'm going to talk about how I made this and some other recording technologies the first step is to head down to the local music store and pick out a few LPS from the dollar bin and of course the electron microscope chamber is so small I can't fit the whole record in there so I cut off a small section the next problem is that the electron microscope cannot image things that are electrical insulators and the reason is that the microscope works by firing electrons at the object that you want to inspect and if the object is an insulator those electrons get trapped inside the object because it's an insulator and eventually if enough electrons get trapped their future electrons coming in will be repelled because like charges repel each other so the way to solve this problem is to coat the object in something conductive in this case I mounted the pieces of record to a glass microscope slide and then loaded the slide into a vacuum chamber and evaporated some silver metal onto the pieces of LP normally this is done with a machine called a sputter coder but my sputter coder needs some work so I'm using physical vapor deposition so this is enough to image the record by itself and I needed to prepare a stylus so that we could see the dynamics I really wanted to see the animation of the needle flowing in the LP groove so I also got a cheap stylus and cartridge from the same music store of course from the used needles bin and most of it is plastic and even worse there's a couple magnets inside there so the way this works is that the stylus vibrates because of the grooves in the LP and it moves the magnets near a coil and that's what generates the electricity that gets amplified into the audio signal also unfortunately if we put this directly in the electron microscope those magnets would deflect the electron path and distort the image so I pulled the magnets off of the stylus next I needed to make us sort of primitive tonearm that I could put inside the electron microscope chamber so that there would be some amount of tracking allowed like a little bit of compliance so that I could push the needle into the record without it you know destroying the record but still have it follow the groove so I just used a piece of copper wire and melted it into the side of the stylus and then cut away all the excess plastic so this is what I was left with I also noticed that there's sort of a rubber suspension on here so that the actual stylus arm is electrically isolated from everything else on the stylus like the plastic and everything so I added a tiny copper wire and then use conductive carbon glue to make sure that the stylus arm itself was grounded or at least electrically connected to everything else this particular electron microscope has two separate stages inside with their own motion controls so this allowed me to put the needle with its you know sort of makeshift tone arm onto one stage and then put the piece of LP that's been coated with silver onto another stage and then I could move both of them independently so that I could arrange it to make an aesthetically pleasing image after getting everything aligned it turned on you can see the video image that the electron microscope creates so it is possible to get real-time imagery this is running even at close to 60 fields per second but the resolution in this mode is quite poor and so is the contrast the signal is very low in order to make a decent image the scanning electron microscope requires about 10 seconds per frame to scan it out so what I did was use the micrometers the controls on the emotion controls on the stage to move the record by a very very tiny amount about 50 microns and then take a still frame and I'm using my Tektronix MDO oscilloscope to store the data so the procedure you know I kind of got in the rhythm of doing it so it's moved 50 microns take a frame save it to the USB stick moved by 50 microns take a frame you know saved at the stick and so I eventually ended up with 60 frames each spaced about 50 microns apart I used a couple felt tip marks on the CRT on the scanning electron microscope to for as reference points so since the position of the LP is not perfectly 90 degrees to the scope or perfectly 90 degrees to the movement axes I was actually moving in two axes and then using those marks on the screen to sort of maintain a the rough the rough position of that needle would stay about the same I processed the data from the oscilloscope in octave which is a an open source MATLAB alternative and then took the images from that and processed them in Photoshop using batch processing and then used Photoshop to create the animated gif the playback speed of that animated gif is about one four hundredth actual speed if the record we're playing as you can see the stylus doesn't move up and down or side to side in the record groove since this is a stereo record it actually has two channels of audio information encoded in one groove so diagonal movements sort of bottom left to top right is one channel and bottom right to top left is the other channel so depending how the magnets move based on the vibrations picked up by that needle tip you can get different signals sent to each channel so then I thought well this is cool maybe there's some other interesting recording formats I can take a look at and yeah just in the last week or two my friends at evil mad scientist laboratories reminded me or showed me this for the first time this is a capacitance electronic disk a very unusual video format that was developed by RCA that was sort of a commercial failure so they're kind of hard to find the disc comes in this plastic caddy and you put this whole caddy in the machine and the machine would open it up and pull out this basically video phonograph it's it's an analog device it's basically it has a track just like audio LPS do it's just that the information density is so much higher the track spacing is really tight so you can actually see the light diffraction patterns in this device so here it is under the sound and I've put it next to the phonograph needle tip just for comparison as you can see the track densities incredibly tighter and the method of storage is not quite the same whereas on an audio record the needle is actually vibrated by physical cuts in the track on this capacitance electronic disk it's actually the depth of the track that makes the signal and the needle doesn't really move and down so much as the capacitance between the needle and the disk changes interestingly this this capacitive electronic disk is somewhat conductive and the capacitance between it and the needle is measured and as it spins around the track thickness varies or the trench depth almost the varies so as it spins you get this signal correlated with the capacitance change as it goes around it sounds incredibly difficult to do technically and indeed it took RCA from the late 60s all the way to the early 80s to get this out and by that time VHS beta and even laserdisc had pretty much you know toasted it so this format was dead on arrival and RCA lost apparently hundreds of millions of dollars I also wanted to take a look at a cd-rom and these are read with a laser of course that we can't just put this in the electron microscope either even though the the metal is aluminum it's behind plastic so on this side it's just polycarbonate on the surface and on this side it's this protective lacquer label so if we put this into the SEM either side up all we'd see is a smooth surface if anything because there's actually no bumps on the surface that's that's good because it protects the media so I spent a long time trying to figure out how to expose the aluminum part at first I cut off a small bit and put this into methylene chloride and that dissolves the polycarbonate base really well and you're left with this very thin almost falling apart piece of aluminum that has the the pattern printed into it but I had problems with a trace amount of plastic being left on the surface and it was just so curled up it didn't work anyway I tried a bunch of other things and then I found out the thing that works best is just double stick tape just get some really strong double stick tape and stick it down to the top of the disc and pull it off and now we have a really fresh sample of aluminum here and so if you come in with a multimeter this is actually quite conducted this is bare aluminum exposed so here's what the cd-rom looks like and of course this is a digital format so instead of having a track vary in width or depth the track is predefined and then there's pits and lands carved into it of course the width of this is even smaller than the redic this capacitive electronic disk we're down to about a 500 nanometer wide pit and I think the track spacing is about 1.6 micron of course I also wanted to take a look at a DVD and so unlike a cd-rom that has the aluminum layer and a protective lacquer on one side the DVD is built sort of like a sandwich where it's got a polycarbonate discs on the top and the bottom and the aluminum information layer is in the middle so to get at the aluminum we just separate the two parts and then that exposes the raw aluminum surface the tracks facing on this DVD is only about 700 something nanometers and this is getting near the limit of the resolution that I can pull out of my scanning electron microscope in its current condition at least okay see you next time bye

Channel: Applied Science

Views: 5,407,444

Rating: 4.8884773 out of 5

Keywords: Electron (Subatomic Particle), Microscope (Invention), Electron microscope, SEM, Ben Krasnow, Applied Science, Krasnow, vinyl, LP, record, sound, audio, recording, close-up, macro, slow motion, Physics (Field Of Study)

Id: GuCdsyCWmt8

Length: 9min 39sec (579 seconds)

Published: Sun Jun 14 2015

Reddit Comments

[u/diode_milliampere]

The CD and DVD close up... completely and utterly fascinating.

[u/krishary]

This is exactly how I would go about doing this.

[u/fillsee]

What language was that, I feel dumb

[u/straylittlelambs]

Well cool.

[u/Die_Hard]

Jiffy! 0:14-0:23

[u/dodgersbenny]

I'm just blown away that a human being invented any of this. Like... Vinyl records... whaaa, how? How anything works on this planet is a mystery to me.

[u/NathanielC]

Used Needles

[u/mattcnz]

Jesus, the breadth of knowledge this guy has is incredible.

[u/RscMrF]

It's great. The record player is such old technology too. I wonder how it was invented.

Ah of course it was Thomas Edison. What a smart guy.