What is the Flattest Material?

[@BreakingTaps]

*Addendum* - Flat != Smooth, _please_ don't fill the comments with hate.

[@graealex]

Did you know that "flat" and "smooth" means different things? 😉

[@maxmustermann5353]

@Breaking Taps pin it to the top!

[@BreakingTaps]

@@maxmustermann5353 Whoops, cheers. Pinned!

[@2lefThumbs]

Yeah was going to comment on the colour, then the lambda/x thing. Lambda /20 means the surface as a whole doesn't deviate from being flat by that much, they generally give a scratch/dig or similar rating along with that for local deviation/ roughness. A lot of flatness testing in general metrology is done using sodium's yellow lines btw, optics suppliers favour 633

[@kubeek]

can you please elaborate on how "RMS roughness (Sq)" is obtained? Is it the same thing as RMS of points on a single sweep line, just accounting all the height measurements in the measured area? And the peak numbers at say 2:45 are 30nm above the average and 9nm below the average?

[@ross123540]

please do a harddrive platter.

[@jameswkirk]

And a hard drive read/write head...

[@tootalldan5702]

@@paulvolz720 thanks for the link

[@TheAlanSaunders]

@@tootalldan5702 I do not see a post from @Paul Volz or a link.

[@TheAlanSaunders]

​@@jameswkirk and @Ross Harrison: I was a CE with IBM UK in the 1970s and 80s spanning the era of large multi platter "removable disk packs" to large multi platter fixed disks. I often gave presentations with diagrams showing the flying height of the heads compared with a particle of smoke or a fingerprint. IIRC, the heads had a radius of ~200' (~60m) to enable them to fly like an aeroplane wing. With my limited understanding of aerodynamics I believe that the surfaces of both the disk and the head would need some regular variation to provide optimal lift; much as an aeroplane, especially a glider (sailplane) flying close to the ground obtains an advantage compared to flight at altitude. I doubt that even modern HDDs with 5 nM flying height can compete with 'the smoothest surface' but they probably have strict limits on the variation of the maximum and minimum deviation from the mean.

[@josephking6515]

Oh yeah, good one! 👍👍

[@kongwashere]

Reminds me on having once been told by someone from ASML that the mirrors they use for their latest Extreme Ultraviolet Light Lithography machines are made at a precision (roughness

[@grimchameleon0546]

Just like the real Netherlands

[@peterfireflylund]

Sounds about right for the tallest mountains in the Netherlands.

[@inventor121]

Sounds like saskachewan. It's so flat you can see the curvature of the earth from a fencepost.

[@Kuiper39]

Fun fact, It is even more extreme than that! I did an internship there. They polish the mirrors to a nanometer-level scale, that would be the same as flattening Germany to a millimeter ;).

[@phillgoodall8838]

@@inventor121 LOL!!!

[@felixpelletier4296]

The flattest surface is the Earth, of course 😉

[@BreakingTaps]

I very nearly made a joke about that, but decided not to tempt the fates / internet 😂

[@felixpelletier4296]

@@BreakingTaps I've got you man

[@mattfleming86]

Shhhhh.... they'll find us! We might want to barricade up.

[@ChrisHarmon1]

In all seriousness, this is not a joking matter. Idiocracy was a prophetic documentary...

[@StormBurnX]

@@ChrisHarmon1 the smoothness is in the flat-earthers’ brains, then.

[@bkm83442]

I worked in the semiconductor industry for 12 years. We could regularly achieve thin films (e.g. Titanium Nitride or Silicon Nitride) on silicon wafers with less than 0.1 nm roughness and flatness.

[@dustinyoung3069]

Thats... less than 100 picometers- wowzers. I get why quantum entanglement is a concern for those tiny-ass logic gates.

[@Minechief_1]

@@dustinyoung3069 your thinking of quantum tunneling

[@caterpillar6298]

@@Minechief_1 that too

[@janami-dharmam]

Just to have a reference, 0.1nm is smaller than the diameter of a hydrogen atom. A single molecule layer of Si3N4 will be much thicker than 0.1nm but the smoothness will be dependent on the underlying layer geometry and topography

[@lightlaserstarwars]

The silicon he showed is bad. Silicon out of the box should be up about an angstrom roughness over a few micron scan. Measuring roughness with an AFM is limited by the tip. Older tips will blunt and give a lower roughness

[@wouldntyaliktono]

You are the reason I am now being aggressively retargeted by atomic force microscope advertisers on KZbin.

[@BreakingTaps]

😂 Sorry! haha :)

[@noelsnave9395]

Just buy one

[@anotherriddle]

Haha, the same here. The funny thing is, I don't mind at all. That stuff is really cool! I also had a phase where I got ads for 5 Axis simultaneous CNC machining centers, Oscilloscopes, function generators, ... And Amazon is asking me if I want a business account. No, this is for my hobby, lol. Would be nice if I didn't have to pay taxes. xD

[@Dmanning11]

I don’t need one, but it’s now on my Christmas list 😅

[@DankNoodles420]

ooof no ad blocker

[@Ben_Kimber]

In the case of mica, it has what is known as a “cleavage plane”, where the attraction between molecules is strong in a certain direction, but weak in other directions. Muscovite and biotite, both types of mica, exhibit perfect cleavage along a single plane. Halite, which is the crystal formation of NaCl, has three cleavage planes in a cube shape. This is cubic cleavage. Calcite is a mineral often mistaken for quartz, based on appearance alone. The major differences are that quartz is more than twice as hard, quartz doesn’t react to hydrochloric acid while calcite reacts vigorously, the crystal habit is different, and quartz doesn’t cleave, it fractures in what is known as a conchoidal fracture. Quartz has no cleavage planes. Calcite exhibits rhombic cleavage along three planes, all at about 75°. Anyway, I was interested to see mica in the video, as I have been taking geology courses in university.

[@davidtatum8682]

Wow. Are you a wizard?

[@Ben_Kimber]

@@davidtatum8682 Probably not. I don't always arrive precisely when I mean to.

[@davidtatum8682]

@@Ben_Kimber Well, I'm sure that you just need to tweak something somewhere.

[@skilz8098]

@@Ben_Kimber So you can understand markings on a page?

[@randoprior4130]

@@Ben_Kimber cubic cleavage sounds like something out of a tomb Raider game...

[@andymouse]

We used to use Mica for LEED or ' Low Energy Electron Diffraction ' because of its atomically flat surface it was used as test samples to put the instrument through its paces, I cant get enough of this stuff !....cheers.

[@tootalldan5702]

I wonder if the Mica surface coating with a plasma spray would be just as flat.

[@tonyb7748]

My mother worked for Rec Silicon back in the 80's. she was a machinist and also a lab engineer. sometimes when a wafer would be out of spec, she would make insanely thin throwing stars or snow flakes from them to give to us as little presents. We would also get huge globs of silicon that looked like 5" slugs that melted. Some had some pretty interesting shapes to them, top hat, sausage, spaghetti etc. don't know what happened to them but she told me on several occasions that the materials were worth about 150k a pound before they were messed up.

[@MakeTechPtyLtd]

The 3d scans you've made are so awesome! Well done.

[@BreakingTaps]

Thanks! Blender is super rad :)

[@jcsjcs2]

I think it's a 2D scan. Height is measured and used in the plot. Definitely nice.

[@alexeynezhdanov2362]

@@BreakingTaps Actually, it might have been better if you aligned these 6 pieces not by the lowest point but by the average point. This way you wouldn't have these plateaus.

[@onegerard1]

@@alexeynezhdanov2362 might that not be due to the speed of the chisel? say yes please i am so sure

[@jimbobjoe]

those high points on the slide are most likely caused by roll "pic out" when the glass is floated, the roll's that lift it out of the tin bath are touching glass that is 1200ish F. The glass is still slightly tacky, and the roll's can stick and cause these little tiny pulls on the glass as it conveys down the line.

[@Obladgolated]

Nice info, thanks!

[@MagicMahn]

I work in a fab where wafers are very prominent. Some moron stacked a bunch of wafers on top of each other. Let me tell you getting those apart took some work.. even trying to slide them apart was difficult. Felt like magnets. Cool to learn more detail about them.

[@michalchik]

I wonder if soaking the stack of wafers in helium or hydrogen gas at a reasonably high temperature would have been a way to separate them especially if you stack them on their side so they didn't have any gravitational force pushing them back together. Basically the gas would intercalate between the sheets and maybe allow them to gradually move apart, especially if they were under tension of some sort

[@MagicMahn]

@@michalchik Inside a vacuum,, our machines actually use helium on the bottom side of the wafer to try and push it up when it's stuck. The surface it sits on is so fine that it too feels like a magnet. The surface also gets turned up to 60C to help relieve the stuck-ness. If we attempt to push it up pass a certain flow of helium (5-15 sccm) we risk blowing the wafer to pieces when it releases.

[@MoDawdy]

work at a fab too.... breaking wafers is far more interesting....

[@deividasleonavicius5071]

@@MoDawdy And that's why we have a chip shortage

[@ralanham76]

So when you work at the fab do high five and say fabulous 🤩

[@michaelzumpano7318]

You’re a really good explainer of technical stuff! That was easy to follow, and packed with information. This was the first video I’ve seen of your craft. It was a great introduction. Thank you.

[@mcdoj2763]

"Do you want to experience true level, Morty??"

[@Molb0rg]

yes, yes, i'am lol

[@Guilherme-vh6co]

LAMBS TO THE COSMIC SLAUGHTER!!!

[@Ranch321]

@Emory Mason was about to say i was about to say a similar joke b4 i saw this

[@palleppalsson]

Yup, found the comment I was looking for.

[@erkintek]

I expected this joke

[@CR3W1SH03S]

Mica is crazy!!! Nature blows away the very best man has to offer. It really is an amazing world.

[@cactiman6593]

It blows away the best of what most of man could do. Scientists could do better

[@UncleKennysPlace]

I grind lenses and mirrors as a hobby, and flat (and smooth, as well) is more difficult to achieve than a figure of revolution. We settle for "quarter wave" but aim for the limits of our [optical] measuring capabilities. For smoothness and final figuring we use a lap of pitch, and cerium oxide or rouge to polish. Great fun for an introvert. PS: I've been buying stuff from Edmund for half a century.

[@peteabc1]

That's something I want to learn. How it's done? With the 3 flats?

[@Obladgolated]

I got to visit a factory in which a lot of Edmund products were manufactured. Gratings, Ronchi Rulings, reticules, first-surface mirrors, all that sort of thing. It was in a formerly industrial area of Philadelphia, and was owned and operated by a somewhat eccentric (but brilliant) man who once worked on the team that developed the guidance system for the Sidewinder missile, back in the 1950s. He told me a fascinating story about how they got that missile to home in on an infrared source in flight, using all analog electronics, no microprocessors, no stepper motors. Truly impressive level of ingenuity.

[@alwayscensored6871]

Use a big piece of Mica?

[@petermgruhn]

@@Obladgolated Right up my Dad's alley. He probs would have liked to talk to the guy.

[@richtomlinson7090]

@@peteabc1 i worked in an Optical lab, and sometimes we would need Plano lense. I would grind the lenses on a Coburn lens generator, and grind at the flatest curve possible and reposition the lens four times, and it would be bumpy. We take that lens to a Sphere Pot, and use our 0 diopter lap, and rock it in and out of the center, and after awhile it gets quite flat. We sometimes needed a lens that was just Oh So close to flat, but when using the sagometer, it would read just a hair convex, and when we would epoxy it to a flat dive mask, it wouldn't trap bubbles between the stock mask and the Optical lens, and it would seem totally flat, but not quite. When I would grind carbide in a machine shop, we had a large diameter lapping table that would create the first reference side to grind all other sides for carbide cutting tool inserts. It's almost easier to create a pretty good flat, than to purposely miss the mark and make a minute curve I now work in a Granite shop, and Granite countertop materials are only real close to flat, but appear flat.

[@wsshambaugh]

You have all the pieces to do a project I’ve been thinking about for a while. A few years ago as I was leaving an aerospace job, our mechanical guys were raving about a new surface finishing method coming onto the market. Basically, you’d do a Fourier transform of the surface roughness to extract the spatial ‘frequency’ content. Then you’d put your object into a tub filled with a uniformly sized sand-like media, and vibrate it at those frequencies (I forget how they transformed freqs from distance to time), and you could notch down the specific frequency content of the surface roughness. Apparently it gave much much better polish to complex geometries that are hard to polish otherwise.

[@ramradhakrishnan9382]

Frequency, yes. But how would the phase be controlled - would there not be a kind off bad phase-lock that would dig the valleys deeper?

[@wsshambaugh]

​@@ramradhakrishnan9382 I don't remember all the technical details. But I don't see how that would dig valleys deeper - it could widen them to be sure, but an impact normal to the bottom of a valley would be just as likely as an impact normal to anywhere else. Phase shouldn't matter too much.

[@squelchstuff]

Wow! I knew mica could be cleaved to restore its optical properties in furnace windows, but I wasn't aware how flat it actually was. Another eye opening episode. Oh, and I chuckled at the shirt.

[@bazoo513]

I don't know what is more fascinating: your videos or a wonderful bunch of experts and/or knowledgeable nerds they attract. 👍

[@5thearth]

Re: the oxide (glass) layer on silicon wafers: I used to have a job at a wafer company. One step of the cleaning process was a soak in hydrofluoric acid, which would dissolve the oxide layer and expose the bare silicon. You could tell when the process worked because silica is hydrophilic, but silicon is hydrophobic. A pre-HF wafer would be "wetted" when rinsed with water, but afterwards the water would bead up.

[@eagames456]

Quick question: Does the oxide layer on the wafers prevent the semiconductor contacting the cooler/ heat spreader on top of the chip? I always wondered why conductive materials could just be squeezed onto CPUs without messing with the transistors underneath.

[@5thearth]

@@eagames456 finished CPUs and other chips are coated in a protective layer of epoxy. You never actually see the silicon itself in a finished chip.

[@stuartgilroy]

I knew they used hydrofluoric making chips because of a terrifying story I heard from a friend who worked for Microsoft in the 90's, but I always wondered what it was actually used for. Thanks Ian

[@Mae_is_gae]

Oh damn, bone hurting juice

[@mayhemdiscordchaosohmy573]

1st time on your channel. I enjoyed it immensely! I knew mica was molecularly cleavable but did not know it was molecularly flat! Here's one for you to check, Scalpels, there are specialized scalpels that use obsidian for the cutting edge because it can ubtain and hold a sharpness down to that molecular edge! I'd be curious to know the actual thickness and what, if any variation on the exact edge is?! (EDIT - My apologies, *OBTAIN not

[@eulemitbeule5426]

2:20 Green wavelength of 630-ish nm? No, that's red (from a red HeNe laser). Green is around 500-530 ish

[@BreakingTaps]

Sweet lord I'm bad at life. Addendum additions already! 😂 Cheers :)

[@chuckvanderbildt]

@@BreakingTaps You're still an exquisite explainer of complicated concepts, and if you didn't make the occasional mistake we would get suspicious :P

[@ShopperPlug]

He's probably color blind lmao

[@Kepler_2258]

i was going to comment this but you beat me to it lol

[@curtisoliver1006]

Will be 632.8nm.

[@wirebrushproductions1001]

You ought to mention that the mica is only a perfect surface over a certain range. At about 7:46 you see lines where you're jumping from one crystal plane to another. Showing a scan of an area with that change would be really interesting, in order to show just how big the steps are. At any rate, it's easy to find uniform surfaces larger than the FOV of of your microscope, but they are not arbitrarily large.

[@BreakingTaps]

Yep that's a good point! And that the surface degrades over time as it's exposed to air.

[@LaserJake99]

632.8 is red HeNe transition, not green. It is typically used for flatness specs so 1/20 lambda would be 632.8/20 I believe the 589.5924 sodium D lins is used for refractive index measurements. No real reason not to use a green wavelength such as 532 yag SHG, except the HeNe lasers are easier to control single frequency or Zeeman split modes for very long coherence length which is needed for precise interferometric measurements. That's why 632.8 is a standard today.

[@jamesmauer7398]

I was going to comment on this also - glad to see someone else noticed.

[@luanskrelja232]

I often work with gage blocks and it fascinates me that it's so rough, you should take a look at a milled metal part it's probably very rough but it can sometimes look very nice

[@coryroberts7519]

This is insanely impressive! We have outcrops of mica around where I live and as kids we would sit sometimes for hours peeling the layers of this mineral!

[@SoulDelSol]

Same

[@GabeUnger]

You are such an underrated channel. You explain things so wonderfully, and your passion about the topics are evident. I love it!

[@Bl4ckw0lf1]

I think that he ranks up there with Destin, Kevin, Steve Mould, Tom Scott, Captain Disillusion and Beekman.

[@lotharerkens8154]

Have you tried to microscope slide's other side, too? One side was in direct contact withe tin bath and will have tiny particles of tin bonded to it, the upper side was only in contact with air and should have no contaminants embedded. For windows we actually have to identify the "tin side" as it has slightly different reflective properties.

[@imdrunken]

Was looking for this comment!

[@terrygoyan]

How do you identify the tin side?

[@EricLS]

@@terrygoyan second this question

[@Taydrum]

@@terrygoyan By looking at it, and you can tell because of the way it is.

[@alessi4249]

Weird to think that a 7nm chip a single transistor would fit on that measured section of silicone. Thanks for the great video!

[@DjBigRed1000]

I am usually hesitant to watch videos with "click-baity" titles (like ______will surprise you!), but I gotta say, that WAS an incredibly flat surface, and I actually WAS surprised by the source! Fair play, sir. Subscribed.

[@WoodenWeaponry]

How your channel has not blown up completely is beyond me.

[@warrax111]

Its because youtube algorythm doesnt recommend his videos very often. I see it first time recommended, and first video watched, and he's up 3 years. So that's the reason.

[@navinpatil9693]

Nice comments on flatness and smoothness and yeah atomically flat and optically transparent MICA is the main substrate used in challenging surface forces apparatus (SFA) experiments to study interfacial and surface forces between adsorbed layers of materials on mica. Cheers!!

[@thewokal5641]

That one dislike was a disappointed flat earther

[@lordjaashin]

na it was your smooth brain.

[@numby1679]

@@lordjaashin no u

[@livedandletdie]

It was probably someone who is against the unethical Mica mining which is basically 80% Child Slave Labour.

[@allyourcode]

TSMC: Check out this super smooth wafer. Mica: *laughs in atomic flatness*

[@gabewrsewell]

very cool! i was able to guess what the smoothest surface was going to be after i saw that atomic terrace surface in the unoxidized silicon wafer scan in that paper there! so i guessed about 5 seconds in advance, i count that as a win

[@WJRHalyn-jw2ho]

Not only a win, but possibly an 8 outta 10 on the psychic forecasting scale!

[@gabewrsewell]

@@WJRHalyn-jw2ho rockhounding as a kid has paid dividends!

[@BrianFedirko]

that just really blew my mind. thank you so much for doing this! It really makes me appreciate my glass slides more... amazing.

[@maxmustermann5353]

Interesting. What about microscope cover slips? I'm not sure how they're manufactured, but to my knowledge, the float technique can't produce glass this thin.

[@BreakingTaps]

I should have some kicking around, I'll give them a scan when I get a chance. IIRC they looked pretty rough/crude when I last looked at them (visually by eye), perhaps they have to be ground down from a larger piece? My coverslips are _super_ cheap chinese variety though, i might try to grab some proper lab grade ones for a fair comparison.

[@maxmustermann5353]

@@BreakingTaps Would be super cool! :-)

[@DVL_Main]

I just finished the second Three Body Problem book. The scene where they discover the probe is a perfectly flat surface and what that meant was awesome. Cool to see that even the most flat item you could find is still bumpy by appearance at a micro level is neat.

[@paulvolz720]

great video! aluminium has a better reflectivity than silver in visible light. it is often used for mirrors in high precision instruments because of that. silver is only commonly used in mirrors because of its corrosion resistance.

[@jimurrata6785]

As long as there are no traces of sulfur in the environment. Otherwise silver does tarnish quite readily. It doesnt develop pits like aluminum oxide does

[@primus711]

Why silver isnt used for contact pads in electronics even though its the best conductor

[@jimurrata6785]

@@primus711 Silver tarnishes very easily. This creates a lot of resistance. It also doesn't have a high melting temperature, and that could be important if you are passing a lot of current. Meanwhile... I have a bunch of high current relays with silver contacts. 🤷‍♂️

[@Sembazuru]

@@jimurrata6785 I've occasionally come across old silver coated component leads. You need to remove the tarnish layer (either mechanically or chemically) to properly solder it. The RMA fluxes that I usually use for soldering does nothing to cut through the tarnish layer. For relay contacts, hopefully the contacts are designed to provide a small amount of mechanical wipe when closing to break through the tarnish layer to get to the conductive silver.

[@rockspoon6528]

If you ever do another part, could you do a fiber optic cable? We cleave those to get an atomically-flat face as well.

[@scruffy3121]

the end surfaces of bearing rollers (good quality) are comparable to gauge blocks. The wringing trick works.

[@ChimeraActual]

Jointers and other carpenters who make flat surfaces in wood know that there are three different qualities of flatness and use different tools to address each. Just considering hand tools; Jointing planes, like Stanley #7 and #8 remove waves, smoothing planes, like the Stanley #4 remove bumps, and hand scrapers remove pics. Pics are those those pointy ends of grain runout that lift off the surface when you coat a plank; which is why you use a sanding sealer before the final scraping. Great video, BTW.

[@waldovanderwesthuizen4557]

I really love your work and your videos really communicate the concepts you deal with well. On the other hand I am very curious about how you went from machining videos (breaking taps 😅) to full on physics (breaking minds... 🤯)... I'll be back for the next one... 😌

[@BreakingTaps]

Thanks! And haha yeah... definitely changed the content a little over time :) So the main reason is that I wanted to run some home experiments and projects a few years ago, but kept wanting/needing custom metal parts. Throw in a bit of This Old Tony binge watching and a cheap milling machine for sale locally, and I got distracted from my original projects and started learning machining instead. Thought it would be fun to document on YT and then one thing led to the next and here I am scanning mica with an AFM :)

[@waldovanderwesthuizen4557]

@@BreakingTaps I completely understand how a person can get sidetracked working on physics experiments. For me, my greatest manufacturing hurdel is needing custom glass parts (scientific glass blowing) rather than metal parts. I want to replicate the early (middle to late 1800s) vacuum physics experiments that was built using glass. Things like the Sprengel pump and Crookes tube.

[@springbloom5940]

I ground my own 1/16 wave secondary, from a pyrex blank. The technical term for 'flat', is 'infinite radius'.

[@johnnyxmusic]

Some guitar players like it that way.

[@springbloom5940]

@@johnnyxmusic I prefer a 9.5" radius

[@johnnyxmusic]

@@springbloom5940 I don’t think many players really prefer a flat fretboard. I’m just trying to make a joke. I mean classical guitars have flat fretboards.Even super-shredder guitars have like a 20 inch radius. 9.5 inches sounds like a wonderful improvement over 7 1/4 inch Fender original. I’ve never played a guitar with a compound radius…that might be interesting.

[@springbloom5940]

@@johnnyxmusic Im missing my index and middle fingers, so a tight radius and narrow neck give me better access up at the nut and more leverage in my grip. Fender started using 9.5" in the 90s I think.

[@BobWidlefish]

I love high precision work, awesome!!! I’ve never done anything with flatness or smoothness, though I have played with very small increments of time. Some of the things you have to measure in computers and networking only take a fraction of a nanosecond, so you have to think and measure in pico and fempto and yakcto seconds. :) High precision is difficult though fun!

[@whatelseison8970]

Gesundheit

[@WJRHalyn-jw2ho]

"femto" "yocto" IF you're going for "precision"... (micro-, nano-, pico-, femto-, atto-, zepto-, yocto-, etc.) (And there are still people who believe "zepto" was one of the comedic Marx brothers. ;-D )

[@RobWhittlestone]

Absolutely fascinating peek into a world I don't know very well! Thank you for making this video. I did my physics degree with final year dissertation in solid state atomic crystal modelling so got excited when the mica was being split! All the best, Rob in Switzerland

[@Alexander_Sannikov]

hey, some good stuff! was quite surprised to learn about precision ground quartz, about normal glass slide and mica.

[@hbmike47]

Your mention of glass slides brought back a flash memory from about 50 years ago. I was working a summer job at hospital lab and for a time was assigned to the PKU lab. There, one person was responsible to run all the PKU tests (Guthrie heel blot cards) for a very wide region. Economy of scale was key in what was a total manual process. Anyway, the lady who ran the lab brought in silk fabric and had me hand polish hundreds of new glass slides Apparently it cleared roughness that interfered with the test. Why silk? Apparently it's quite strong stuff so the threads on a tight woven silk fabric resist friction wear and shredding and can polish the small pulls or contaminates off the glass surface without scratching. Anyway, it's an easy experiment you might try.

[@jimquinn]

I suggest the book "The Surface Texture Answer Book" by Malburg and Musolff (2021) for the definitions of roughness, waviness, form, lay, and profile. When you say "RMS", I assume you are referring to Rq or Sq. Great video, again!!

[@BreakingTaps]

Oh, rad thanks! Will check it out! Definitely not my field of expertise, as evidenced by the sketchy explanation about flatness and roughess (I realized halfway through explaining I wasn't quite sure... you can see the panic haha). But yes you're correct, the RMS numbers I was quoting were "RMS roughness (sq)" values straight from Gwyddion.

[@TheEvertw]

I think the flattest and smoothest surface you can readily find will be a hard-disk platter. They have a roughness of about 0.1nm (!), according to the first source I found on the internet.

[@EricDalgetty]

So was the mica you scanned the piece that you had just sliced? Or does it look that nice right from the beginning? Really cool video!

[@BreakingTaps]

Different piece, I filmed the cleavage bit the day before so I ended up cleaving a fresh piece for the actual scan. If you let the freshly-cleaved surface sit too long, it starts to react with the environment and pick up defects (the crystal has a lot of dangling K+ ions, which start to react with water and CO2 to produce tiny carbonate crystals on the surface over time) But it's pretty representative of what you see. Super flat and free of particulate, although if you're unlucky it is still possible to land on a "step" where the layer breaks and you go up or down to a new sheet. You can see those "steps" on the piece I cleaved as little concentric circles. They are like millimeter sized though so pretty easy to avoid.

[@normanhairston1411]

Originally, Corning's fusion glass process was to make car windshields. However, the float process was invented at the same time and float had adequate flatness but was much cheaper. Corning kept its fusion glass process running making microscope slides. It was useful as microscope slides because it was virtualy perfectly flat as the glass surface was not polished and was never touched by anything but air. The particles on the slide you have are probably chips from the slied cutting process. Of course, eventually LCDs came along that needed fusion glass flatness and that is the primary use of fusion glass today.

[@MrShkolololo]

Great video! But It would be better to trim experimental values only to significant digits: maybe to tens of a nm, i think, as no AFM can give significant data up to 5-6 digits

[@BreakingTaps]

Yep, very fair point! Was just being lazy copy/pasting from Gwyddion 😅

[@mayhemdiscordchaosohmy573]

Sorry 2nd comment but I believe you may find this interesting. Oh something I just remembered that is almost pertinent to this vid....! There was an experement done a couple Swedish Sientists to determine human tactile sensitivity! The volunteers used their dominant finger to determine the smoothness of a surface and the results BLEW my brains out behind me and painted the wall exhaust-hood grey! We're able to detect a roughness of, get this, 13nm tall....actually check out Science Asylum's vid "If Earth was small, could we feel the details" @ 8:35 counter time and the details of how sensitive human touch is! Mind blowing...more sinsitive than the 90s man!

[@DeathBringer769]

"One of the flattest materials, and the source will surprise you" Probably came from my ex-girlfriend...

[@superxdish]

You beat me to it dammit

[@malokey7]

Mica is used in cosmetics so maybe there is some truth in this

[@ihaveseverefrootsnackism]

mean ;(

[@A-10goBRRRT]

you have succesfully made me clean my screen to really appreciate the mica's flatness

[@benjamincolumbus]

Thank you! I find everything in your videos so interesting, but don't have the means to do this kind of thing myself. I find your videos to be very valuable learning resources.

[@dennisk5818]

This was a fascinating discussion. I got to thinking that in the end, as a visual system, the resolution of our eye is so bad when compared to these surfaces, that they all appear 'flat and smooth'. I've also enjoyed the technical aspects of many of the comments.

[@mvadu]

Any chance you have an old hard disk metal platter and source a newer generation higher density shingle drive platter? It will be an interesting way to see how the storage generations improved overtime and shrunk at a nano scale..

[@BreakingTaps]

Hmmm... definitely have plenty of old HDDs sitting around. Unsure if I have a newer shingled variety, will see if I do (and/or obtain one). Not sure if anything would show up but I agree it'd be interesting to check!

[@maxmustermann5353]

@@BreakingTapsThat would be cool! 👍

[@th0m]

Was pretty sure I knew where this was headed from the beginning but it still blows my mind every time. The natural world is so dang cool if you know where to look

[@TheSpeenort]

I had to pipe gases through stainless steel and was surprised that smoothest interior surface had a matte appearance rather than a mirror. The reason was that the polished mirror surface had sharp crystalline edges when seen under an electron microscope and the etched matte finish had rounded crystalline edges.

[@markp5726]

I wonder if they were processed with abrasive fluid machining (AKA hydroerosive grinding). A former employer made diesel injectors, and used AFM to radius the orifices and (IIRC) adjust K-factor. Pumping a diamond-powder-bearing fluid around at high pressure... now that's a recipe for a self-destructing machine!

[@TheSpeenort]

@@markp5726 We were told it was hydrofluoric acid etched.

[@juliannmnnnm]

no 1 is literally exactly what i expected when i started watching. great video.

[@landonkryger]

I once read a report that said humans can feel surface imperfections that are on the order of nanometers. Can you feel each of those samples and tell any difference between them?

[@BreakingTaps]

You can maybe _just barely_ feel something on the gage block, particularly if you can catch a nail on one of the scratches. It feels very very smooth though, and it's very subtle so I'm not sure if I'm imagining it or not tbh. The grinding marks are super apparent by eye though, even if you can't feel them very well, they show up under the light. Not sure I can feel anything on the glass samples though. Slightly rougher items around the shop are very noticeable though, particularly when you get to like the 500nm - 1um range. Pretty impressive when you think about it!

[@peteabc1]

Also interesting is if you've a feedback in hand, like an indicator, you can move it by umeters. The brain figures out you can increase precision by pushing from side without knowing anything about cosines.

[@JohnDlugosz]

What you feel is the effect of roughness against your fingerprints. You don't feel the individual bumps per se, but the roughness will affect how much your skin "chatters" as you drag it over the surface with light pressure. In simple terms, you can gauge the friction and feel the difference between roughnesses that differ in nanometers. I remember reading about research into building sensors that work like whiskers, and how the vibration translates into what it's brushing over.

[@squelchstuff]

The tongue is far more sensitive than the fingers. Windows are in fact pretty smooth. Ask me how I know? :D

[@mfree80286]

@@squelchstuff Professional window licker. Wow.

[@Skeptical_Numbat]

Very intriguing. Now I have to wonder which materials would exhibit ultimate "flatness". What sort of factors would there need to be for better "flatness"? • Would it need to be metallic/metalloid, or could organic materials (like diamond) demonstrate impressive "flatness". • The crystalline structure of the material. Logically smaller crystals would be better, but do they in reality. • Density. Can highly dense metals can be ground/polished to greater tolerences? • Hardness. Diamond & some more esoteric materials.q • State. Does it have to be a solid, or could a liquid exhibit ultimate "flatness" (under certain circumstances)? • Temperature. Can temperature microfluctuations in the surface of the material affect the reading? • What haven't I considered? Specific materials I'd like to see: • Graphene - structure • Diamond - rigid crystalline (monocrystalline?) structure • Iridium - density • Tungsten - Very hard • Molten Tin - already used to make the very smooth float glass. • Water - perhaps under rotation, or centrifugal force. There's also the methods used to cut/grind a smooth, "flat" surface, such as diamond/corundum grit, splitting along the crystalline lines (eg: as you showed with Mica) & then there's using narrow wavelength lasers to both cut & "polish" surfaces.

[@pyjamakid3982]

"Nothing but a flat surface" Mica-chan: "b-b-baka! Im not flat !!"

[@mayhemdiscordchaosohmy573]

Hahahahaha

[@ihaveseverefrootsnackism]

rushia chan ;)

[@mmenjic]

10:32 why not try precisely that, put some particles or interesting stuff on mica and scan it :)

[@billpeiman8973]

How long do these scans take?

[@BreakingTaps]

Really fast scans (128x128) are 10-20 seconds, I use those to roughly find interesting features. Moderately fast scans (256x256) are about 80 seconds and I sometimes use those to sanity check a region, make sure there aren't any super large features that might cause problems, etc etc. Most of the scans I end up showing are done at 512x512 which take 3-4 minutes iirc. Haven't timed it but something in that ballpark

[@billpeiman8973]

@@BreakingTaps Thanks; faster than I expected. I did electron microscope install/repair in the '70s and kept my interest in microscopy.

[@DavidOHara-m8i]

I used to make x-ray optics that required a surface roughness of about 1 nm. I have some large sheets of mica that are 25 micron thick, 5 cm X 10 cm with roughness of about 1 nm. One can buy Si wafers that are about 1 nm smooth. I produced smooth parabolic and ellipsoidal surfaces by coating an ultra-polished surface of electroless nickel with about 300 angstgroms of gold and then electroplating onto the gold. Once separated (gold acts as a release layer), the inner surface is about 1 nm rough. We used AFM to measure roughness but a better tool for these highly curved surfaces was a Wycko profilemeter as it measured over several tens of microns.

[@marcelo55869]

Rushia-chan fans: "Well I know about a surface that is even more fla... AHHH!!!"

[@Protect_all_ljf3forms]

=^) I think the answer of why YT put this in our recommendations

[@bug5654]

@@Protect_all_ljf3forms Can confirm. See you on the other sid-

[@apollo3679]

This is the type of content I want more of in my feed. Awesome explanation and research.

[@enderwolf4555]

The flattest thing ever: my ex’s chest

[@munchkinmeep]

Yeaaah I guessed the flattest one and then watched to see that I was right! This was neat~ I believe mica was historically used for the slide and coverslip on wet mount slides

[@markos.5539]

Flatest surfaces include some waifus

[@risunokairu]

Rushia will find you.

[@iamtheomega]

mica very common in rocky areas of midwest, find chunks of muscovite stacks at random. i think was used as window material before glass in the West

[@oddvertex9429]

Great video - love the shot of the comparative scale at the end

[@nicknorthcutt7680]

So interesting! Thank you for your hard work and great content! 😊

[@jcsjcs2]

We used Mica to demonstrate the proper AFM function of some of our devices. The goal was to obtain an atomically resolved image. Depending on the settings you used, the atoms could look like huge elevations because the cantilever would stick and bend as the piezo scanner continued pulling or pushing the cantilever over the surface. The optical detector would interpret the bending as a normal force, not only a lateral force, making the atoms look like mountains compared to what the should have been.

[@i-never-look-at-replies-lol]

Mica was really abundant where I grew up (along with tufa and obsidian). I loved to pick pieces up and peel off the flakes to see how thin I could go!

[@aquacultureafrica]

Best You Tube video I have seen in a long time! You don't need to be apologetic, you did a perfectly fine job of telling us ignoramuses all about it.

[@eugenetswong]

Thanks for the explantions, and the images.

[@xtYLT2IY8]

i genuinely predicted mica being 1 after reading the title, nice video

[@jamesrosenberg1612]

I've run AFM on mica sheets before when we were trying to put nanotubes on them to measure individually! super cool how flat it is.

[@DutchDiederik]

I'm happy I've found this channel. Super interesting stuff, man.

[@digitalfire01]

I stumbled upon this video randomly, but I learned a lot from it. Thank you.

[@bryanblack505]

This is the nicest comment section I've ever seen. Maybe tied with Mr. Ballen. He has some incredibly nice comment sections as well. Just nerds nerding out. No room for hate or stupidity. Very cool.

[@tp6335]

Some time ago I was in Norway visiting a rebuilt historic house and it had windows made of mica. I still have a block of mica from that trip, fascinating material

[@owenruff4796]

Something interesting to look at would be a mechanical seal since their flatness is measured in helium light bands, probably not as smooth as some of the other surfaces but they are pretty darn

[@hamburgerhamburgerv2]

8:03 smoothness of a Twitter user’s brain

[@Critter145]

Very cool video. Thanks for making it!

[@steveunderwood3683]

If you take a reasonable sized sheet of float glass, and hunt around the surface, you'll usually find significant areas that are exceedingly flat and smooth. I've seen labs doing this kind of scanning to find flats for their own use. A downside for some applications is you can't easily cut the large sheet down to the area in which you found the nice flat, without stresses distorting it.

[@petriepretorius4085]

this is quality science! as much quality as mica surface! subscribed!!! thank you, this is such good stimuli for my science brain...

[@edwaggoner7403]

I worked for a quartz crystal manufacturing company 1974 to 1980. The crystals were used for frequency control in the electronics field. We regularly polished 3/8 " diameter quartz blanks to less than 3 angstroms flat. We did not have an electron microscope. If we had imperfections the product failed.

[@erikisberg3886]

Great video, thanks! Amazing that the microscope slide turned out so flat. I have scavenged good mica from old heating element for some experiments in the past. Irons and toasters may be good finds.

[@joelwatson9233]

I work in metrology, specifically with CMM's and not with optical measurement. Those spikes on the glass slide look a lot like dust particles on a scan done with touch probes. You'd be surprised how small dust can get, I typically use compressed air to get rid of that

[@MisterRorschach90]

The flattest surfaces cost many, many thousands of dollars, require freaking PhD level techs to set up, calibrate, test, and validate, and the tools they use to do it have Star Trek sounding names. I find it fascinating. I actually stumbled upon the craft when trying to find physical evidence that would show flat earthers how impossible a flat earth would be. Ever since then I’ve wanted an aaaa rated surface plate and all the tools.

[@MisterRorschach90]

I’ve never learned about mica before this though. Looks like I’m gonna be splitting crystals.

[@jeffreyyoung4104]

Depending on the size of mica you need, there are large sheets sold for wood stoves, and they were used for many years, as they didn't have high temperature glass when mica was used.

[@a_Minion_of_Soros]

I have been looking at quantum dots recently. This puts some more perspective to it. Thanks.

[@Copesthetic-Aesthetic]

Great video, would have like to see a ceramic gage block, or at least inspection grade. They are ground, and lapped. Inspection grade blocks usually cost twice as much do to a better lapping process.

[@justincase5272]

Cool! Surprising about the mica.

[@FriendlyCynic]

Another way to think about smooth vs flat is like this: I can take a solid wooden bench whose flat from one end to the other, but somewhere in the middle take a razorblade and scratch it. The whole table is still flat from end to end, but the surface is rough because of the scratches from the razor.