How to make Very Flat Optical Surfaces on Glass

[@mccallan2798]

I've got absolutely no idea why this video was recommended but I'm so glad it was. Fascinating. Well done.

[@robotslug]

Same

[@thekeyfox]

Same

[@BootyYeeter]

Same

[@88njtrigg88]

It's because your subliminally interested in light & optics.

[@mcpozzm6321]

It started when I clicked on a bartender showing how to make optically clear ice cubes for drinks, next day this was in my feed.

[@TheWtfnonamez]

Totally counterintuitive. I've done a fair bit of metalwork sanding and polishing, so I naturally assumed that optical polishing would be similar, only using something harder and flatter to grind the surface. It never occurred to me that the rotational grinding process would use something ductile, yet get better results. Thank you very much for the excellent explanation.

[@stanrogers5613]

In metalworking terms, it would be very similar to using an aluminum, copper, or tin lap (as in watchmaker's "black polishing"). You want your lap to be softer than the material to be cut. Your lap becomes a matrix to hold the abrasive particles in place, and the cutting happens on the material that can't just grab and hold the abrasive. (Tin, by the way, gives absolutely amazing results when polishing steel. It's just _really_ stringy to machine when you're initially making the lap. Save it for your finest - sub-micron - grits.)

[@stc2828]

You polish silverware with fine cloth which is softer than silver. If you use sandpaper the result would be terrible.

[@gvidas1338]

Very informative yet old video on lapping metal parts by rotation. Check this: kzbin.info/www/bejne/nJ_Sh4ljh7x8jbs It vey clearly explains "how it's made".

[@sakelaine2953]

@@gvidas1338 This is great, thanks!

[@matter9]

I feel there’s a general misconception when it comes to lapping a polishing that is a result of focusing on the lap material. As the first comment responder noted the lap only hold the cutting media. There are three fundamental rules for cutting to occur, though I only usually remember two. The important one here is that the cutting “tool” (in this case lapping or polishing compound) MUST be harder that the workpiece. The second is that there must be relative motion. The third escapes me. But in either case it is not the lap that cuts the work piece but the embedded abrasive. Apologies for the lecture comment but lapping and polishing seem to be no different fundamentally than any other metal removal process; hard removes soft. In the case of polishing silverware presumably there is some residual polishing compound on the cloth that is the effective mechanism for removing the oxide layer. Also, if I’m glaringly wrong please correct me. 👍 Edited for autocorrect errors.

[@noanyobiseniss7462]

The true test of whether someone has mastered a field is their ability to explain it to the uninitiated in a clear and concise manner, you sir are a credit to the field.

[@hydrocarbon82]

Flat-out the best vid on making flat optical surfaces! Clearly thought out well, I couldn't pitch in any criticism. It's almost like we're on the same wavelength.

[@digitalradiohacker]

What a cheerfully bright comment! I for one found the video very illuminating, and it seemed to polish out all the rough spots in my dull and hazy knowledge. You could say that it expanded my bandwidth....

[@yashsvidixit7169]

@@digitalradiohacker makes me wanna leave my daily grind and do something else

[@bellowphone]

Micronically inquisitive mind lapped up the precision explanations.

[@Asdayasman]

If y'all don't cease with immediacy I'm gonna jump into a woodchipper.

[@DocBree13]

😂

[@frog8220]

How did I end up watching 12min of "how to polish something to the nm scale?" But you explained it so well that I understood it without any previous experience in polishing glass or anything for that matter

[@Kargoneth]

It's rather hypnotic.

[@tombesson7293]

This video reminds me of the optician who fell into a lens grinder and made a spectacle of himself.

[@MikeWiggins1235711]

That's not as bad as the glass blower who accidentally inhaled and now has a pane in his chest.

[@yashsvidixit7169]

@@MikeWiggins1235711 Still not as bad as that chef who, while cooking some some chicken broth, fell into the pot and made a laughing stock of himself.

[@Cynthia_Cantrell]

Clearly, I didn't see that coming.

[@tombesson7293]

@@Cynthia_Cantrell Did you hear about the guy who wondered why the baseball kept getting bigger and bigger, then it hit him.

[@user-hv6wb5gk8p]

Reminds me of the lab technician who spilled some acid on himself. Really left him fuming.

[@TickyTack23]

This is really good, so well detailed. It seems over the years there has been a lot of demonstrations of optical grinding/lapping, lots of "recipes" so to speak, without any detailed explanation as to why it works. I'm coming out of this with a deeper understanding of the process, only took 12 years, but better late than never!

[@shripadwarudkar6487]

Hats off to your narration... I simply was thrilled. I am a retired engineer, 73 yrs.

[@kochipj]

I work in the optics industry for a couple of years now and I have to say that your channel is a real treasure! Your videos are both, highly educational and entertaining. Keep up the outstanding work!

[@Dukey8668]

I have been interested in optical engineering for a long time now and yours is the first channel I have seen that covers it well. So thank you for making such excellent videos.

[@martinthemillwright]

One of the most clearly explained process ever seen on KZbin. Beautiful. I feel like building one of these now.

[@TungstenCarbideTempe]

The principle looks simple, its just a tar and turntable, but those who tried working with glass, especially polishing and making it precise, knows that its extremely hard, takes years of practice and patience. Great video.

[@tomtang2639]

jeez why didnt youtube algorithm recommend this to me earlier??? Its fascinating!!

[@zekeroche7915]

I've been polishing for a year now. This was super informative. Putting images to techniques helps me understand more of what I do all day long lol

[@СергейХомяков-в7э]

I have been polishing precision optics for 12 years, I really enjoyed the video, thank you. I do the final polishing of the optics on a spindle in a zerodur plate with holes, I put planes with weights in them, according to a similar principle. pitch polishing pad for the night I turn over on a plate smeared with Regipol with good flatness

[@MaxRomantschuk]

This is the most satisfying and informative presentation I've seen in ages. As a photographer I really appreciate the craftsmanship required to produce high quality optics. My hat off to you Sir! 🎩

[@SqueakerT]

At work here in Germany they got mad at me for filing like this....that you work in nm tolerances and do so as well made me really happy. The understanding of why one would do it so they just couldn’t understand. Also an amazing video, very informative. Keep up the good work!

[@stickyfox]

I used a machine like this in the 90s to flatten hydraulic motor parts. Instead of pitch, the wheel surface was steel, and the surface was kept flat by adjusting three rings which also kept the parts in position on the wheel. We'd check it a couple times a day by washing the abrasive off and placing an optical flat on the wheel. But other than that it worked the same way.

[@hindugoat2302]

its not the same as true level

[@stickyfox]

@@hindugoat2302 Reality is poison! I can't live like this!

[@stickyfox]

@Andrew Crews I worked on Eaton and Sauer-Sundstrand axial piston pumps and motors. We would replace pistons and cylinder blocks and send them out to be resleeved/refinished.

[@michaelmello42]

I appreciate this comment very much after having done very similar work in the 90s. I used to test lapped and partially polished parts with an optical flat to infer the concavity of the part (convex or concave). Once the concavity was determined, I inferred the lapping wheel's (opposite) concavity and would adjust the rings' position to correct the wheel.

[@subhashkulkarni1117]

Pl.explain the process in detail

[@Dak3]

Using interferometric fringes to test optics, what an ingenious setup!

[@kellymoses8566]

If you think that is impressive the Laser Interferometer Gravitational-Wave Observatory uses interferometry to detect changes in length less than a 10 thousandth of the diameter of a proton.

[@BarneyDesmond]

@@kellymoses8566 luckily we don't need *quite* such precision for optics :)

[@therealzilch]

I've always thought there was something almost magical about being able to make incredibly accurate optical surfaces, flat or otherwise, with no precision tools whatsoever. I ground my 6" parabolic mirror by hand, and figured it to 1/20 wave accuracy on a pitch lap, with no references other than the Foucault test. Very nicely done. Subscribed. cheers from sunny Vienna, Scott

[@robertmccabe8632]

if you like that; then the three plates to make a surface plate is another example of this principle (though wil hardish surfaces)

[@therealzilch]

@@robertmccabe8632 Indeed. I use this principle to keep my sharpening stones flat. Using silicon carbide abrasive, I grind A against B, B against C, and C against A.

[@maxenielsen]

Excellent explanation! I’ve been aware of over-arm polishers for lenses, but not aware of this method. You openly share a lot of which others would consider trade secrets. Even so, I have to believe that if I were to set up a similar polishing system, using everything you show here, I probably wouldn’t get results as good. Thank you!

[@MimicGriphon]

Am I the only one that loves this type of stuff, but at the same time, completely understands how boring most people probably would find it?

[@ramkitty]

Excellent vector drawing demonstrating the constant angular velocity.

[@janpoppeliers8619]

Very clear and detailed explanation, best I found so far (and no irritating background music). Cool how you built the turntable from a washing machine motor and rollerblade wheels!

[@jlmknight]

Very fascinating seeing someone so specialized and advanced in their field, thank you for sharing.

[@PronatorTendon]

I wasn't aware how much I like this content

[@adrianrevill7686]

Thank you, i always wanted to know how it was done. Very clear description.

[@tottedpotato]

Hello youtube algorithm...thank you for suggesting something I didn't know i needed to know

[@williamcashion5262]

It's hard for me to believe but, I lapped and polished for 20 years (Gator Diamond, Inc) and didn't know half of this info. Thanks, Bill

[@davejenkins8524]

I have always wanted to see Mach 3 used in a unique way like this. BRAVO !

[@movax20h]

Fascinating videos, with plenty of details. Thank you for all this useful info and diagrams!

[@turbocpt1]

The explanations you give is perfect. Even a brick can understand this.

[@aerosoapbreeze264]

Your channel deserves more subscribers

[@MindbodyMedic]

this filled in some gaps in my knowledge, really great stuff.

[@matter9]

Excellent. Very happy I found your channel. Honestly, as a nerd in training, a good friday night for me includes such terms as nanometer and interferometry. Looking forward to your next video! Edit: trainings -> training

[@raguaviva]

physicist here, every single video of yours is mesmerizing, I have no words!

[@T____K]

well explained, no questions, sir! great video

[@TheEvertw]

Prachtig werk! Ik heb me altijd al afgevraagd hoe die dingen zo vlak konden worden gemaakt.

[@royalgilpin4922]

This video reminds me of how profound our technological advancement has been. Just think of how many different people had to cooperate and dedicate basically their entire lives to engineering better solutions in the relatively niche field of precision optics. Using a high viscosity fluid as a lapping surface? How the hell did anybody come up with that? Stuff like this just blows my mind.

[@richardlee9685]

When you shut the machine down overnight, is it necessary to maintain the lab at a cool temperature to minimize pitch movement?

[@shannonpincombe8485]

Nah...you just use auto tune. Everybody does these days. Hehehe

[@tjsbbi]

@@shannonpincombe8485 That's how those T-pain sunglasses are made.

[@juliusfucik4011]

I think there is a tradeoff. It would certainly help, but investing in climate control may not be worth it. Also, it seems heating the plate and then weighing it down removes enough deformity in a small amount of time. These techniques are fascinating.

[@thedudeamongmengs2051]

@@shannonpincombe8485 I respect the pun

[@ai_university]

They run 24hrs

[@MajSolo]

good to see that physics works all engineers experience the same when going down to nanometers no matter what kind of engineering they are doing and that is that solid material is moving ( slowly )

[@denisnikitin5894]

Thanks for the video, it's very informative. So the polishing table is an aluminum disk with a motor stator attached to it, and you press the pitch lap by using a granite plate, but I was wondering if you could share what the pitch lap substrate is made of? It looks like a few inches thick disk. Is it also granite?

[@HuygensOptics]

No actually in this particular case it is borosilicate, which has a thermal expansion coefficient that is about 3 times lower than granite (which is an advantage). You can however use granite without problems if you have good temperature control.

[@somewherenear3003]

Today this was recommended to me and I watched till the end

[@Cjerbasko]

Thank you kind algorithm for bringing me here. This was very interesting.

[@W1ldTangent]

The algorithm sends me to strange places sometimes, but it sure can be a fascinating journey. Today I learned something I did not know yesterday, thanks.

[@chris-hayes]

No idea why this is in my recommended, but very interesting. I'm amazed this kind of thing can be DIY with the proper knowledge and materials. I would consider myself a maker more in the software area, it's always cool to see what other people are working on. Keep making!

[@Bill.Pearson]

"proper knowledge and materials"--including an old washing machine motor and rollerblade wheels.

[@DavidG2P]

What a fascinating microscopic world lies behind these seemingly primitive (to the layman only, of course) machines!

[@fearlessjoebanzai]

I can't shake the feeling that I'm learning knowledge that I will never need to use!

[@Bill.Pearson]

Agreed. Like watching This Old Tony.

[@marklimbrick]

Last minute had the information I didn't know I needed. Blocking pitch does put pressure on glass held to a backing. All the old film of spectacles and camera lenses show blocking, but these are not expected to be accurate to fractions of a wavelength. OK now I will also avoid lots of messy cleaning up as well.

[@gkelly]

I would have never guessed that you'd use a malleable disc to do the polishing. Really fascinating to see how this is performed, thanks for the video!

[@BruceSchaller]

This is an excellent way to do low speed control with a VFD. Thank you for the good idea.

[@elischultes6587]

This gave me a moment of connectivity to my Grandad. He ground rifle scope glass for a few years. Now that’s not flat but more of polishing

[@fhgx32]

Very good explanations with great schematics. Great video overall.

[@htchtc203]

Thanks you, Sir. Very good explanation of optical polisher.

[@asdf35750]

Using a Fisher and Paykel motor driven by a VFD is genius! So much simpler than the old belt and pulley reduction.

[@youcancallmeque]

i have no idea why KZbin recommend me this video. What more fascinating is i watched it until end, and still have no idea what is that.

[@josephhertzberg2734]

I had no idea about any of this. Fascinating.

[@satankarmukesh3552]

Thank you for nice video, will you please let me know how to make single 40 to 80mm discs flate up to 1/6 wave or 50 nanometre regards.

[@Crobisaur]

Your videos constantly inspire me to want to build my own lenses for different optical projects. Thank you for sharing your designs and knowledge!

[@1NicholasWeir]

Thank you for making and sharing this video! Great content and very informative!

[@bad_spider]

hats down, top grade quality video, so rare

[@DANTHETUBEMAN]

I'm lapping this video up!

[@SF-fb6lv]

Great video. Very very well explained! Brings back memories. I used to make achromats from blanks of optical class at home in high school for telescopes.

[@vladimirlevchenko1470]

Hi. Огромное спасибо за ваш вклад в образование !

[@beaudanner]

So fascinating the science and math that goes into allowing us to achieve this. I would have never guessed it was pitch

[@bennylloyd-willner9667]

Great video, Christiaan would be proud if he was here today!

[@AssmannVerspaning]

So-de-knetter... té gek dit! Leppen van metalen onderdelen doe ik met veel liefde. Leppen met pek is iets wat ik nog nooit gezien heb. Dus: fantastisch om nu met je neus zowat óp de lepschijf te zitten. Met commentaar van een kenner. Hartelijk dank!! Ik kijk erg uit naar de video over de vlakheidsmeting! Groeten - Nobby Assmann

[@nawtdavids]

Really well made video! Great job.

[@stoneybologna1982]

I'm an optical fiber telecommunications technician. We used to have to polish the end faces of our connectors when terminating them. 3 different ratings of polish paper and polishing in a " figure 8" motion. It was tedious. Faster speeds and the need for lower reflection at the connections has us using fusion splicing and factory terminated connections, now. No one misses " puck and polish" terminations.

[@austin5060]

Oh shit Sydor is right down the road from me!

[@mdevidograndpacificlumbera1539]

Do you always use the same grit to polish? If not, do the grits find themselves trapped in the pitch? Do you have to use different pitch plates for each grit?

[@HuFlungDung2]

Polishing is the final stage of producing an optical quality surface and there is only one compound used on a given lap. Grinding the surface to a desired rudimentary curve is called grinding, not lapping. Pitch laps do not grind but only polish. The amount of material you'd remove by polishing is miniscule and nobody wants to waste time doing any more polishing than necessary. Grinding a surface starts as a rough cut to quickly give a desired curvature and to remove casting irregularities. Then a succession of finer grits is used to remove the deep scratches left by the previous grit. This is done with a hard tool on the workpiece and an abrasive slurry is run onto the surface. It looks a lot like lapping with a pitch lap, but because the tool is hard, it can be reliably cleaned off when it is time to change to the next finer grit size.

[@machinetoolswarehouse]

Awesome work! I am going to try this...

[@Santibag]

The closest thing I do is knife sharpening, but I always wondered about stuff like straightness, flatness, and smoothness. This videos was very interesting.

[@johannglaser]

Fascinating, and very well explained! Thanks a lot!

[@rapsod1911]

This is very interesting. I read somewhere that for lapping of silicium wafers they use some chemicals instead of abrasive particles. I can't imagine how precise they must polish wafers for 4nm technology.

[@HuygensOptics]

It's generally a combination of both. If you use a chemical that etches your surface while you are polishing, you can use a very mild (or soft) abrasive agent, which results in a smoother result. By the way, when you use Cerium Oxide to polish glass, chemical interaction also helps speed up the polishing process. For wafers the actual flatness is less important that the smoothness, since modern wafer steppers make a heigh map of the wafer to correct for the total thickness variation when clamping a wafer to the chuck. Modern technology wafers are indeed incredibly smooth and flat (from the dimension of individual components to that of the full chip)

[@smolboyi]

Well made video, and very interesting!

[@fakestory1753]

This video made me happy.

[@pablovicentico]

Amazing video!!

[@matiKRK]

As a Polish, I approve of this video

[@SandyRiverBlue]

I really enjoy your videos....keep them coming.

[@AlohaRaceTeam]

I work at Sydor in Engineering nice video man!

[@fossar_]

I didn't need to know this, but I'm glad I do now.

[@mitchellman4846]

Very good to know, sure I’ll use this someday

[@christopherr4628]

That was interesting and well explained. Good job, I will watch a few more of your videos

[@markwilliams5654]

Great information thanks for sharing 🤠

[@trex70]

Very nice thank's for sharing

[@Sirmellowman]

this is extremely interesting.

[@minercraftal]

Really nice knowledge!

[@jonsydor9048]

Great video!

[@bekanav]

Very good stuff. I've done my share of glass pushing, long long hours of manual work. I tried to make 200mm flats but I constantly got into troubles in 1um (two rings) level... Perhaps I return to them sometimes, even though I hardly remember why I started making them LOL (ok it was some cassegrain telescope idea, and another for testing other flats)

[@sillysad3198]

MAN! this is so smart! the rollerblades to unload the bearing axially!

[@nuramd]

Today is the day i understood why tires have grooves

[@MegaFrankels]

When you go through the grits of silicon carbide or cerium oxide, dou you change pitch plates or clean it very well? How do you make sure some coarse grit doesnt ruin the later polishing steps?

[@HuygensOptics]

The silicon carbide grinding is not done against pitch but against other glass or granite plates. You have to carefully clean and rinse between grains (not only the plates, the work space, but also your hands) in order to avoid contamination.

[@brianmahoney4156]

I love the combination of washing machine and industrial PWM

[@haenselundgretel654]

Wow! Just wow! Cheers mate for the all the Infos! I like your dialect ;-)

[@Sirmellowman]

is this similar to how they make the large telescope mirrors?

[@WhatAWondWorld]

Спасибо. познавательно

[@andreavergani7414]

Great job sir

[@lrakschmidt2880]

I'm wondering if you can put the pitch lap in the freezer when not in use for weeks or months?

[@HuygensOptics]

Sure, that is the way to store them over longer times. It also avoids the evaporation of the more volatile components from the pitch so it keeps the right viscosity. However, even then you have to put some effort in bringing them back in a usable state, because, they will loose shape on the sub-micron scale.

[@lschmidt2405]

When the pitch drapes off the sides, how do you get it back up on top? Do all the different grade abrasives get mixed into the tar? Do you then have to replace the tar? How do you setup for lens grinding as opposed to flats? How are multifocal optical lenses ground? eg for spectacled?

[@ccaissie113]

freeze then chip it off and melt and recast. the polishing compound is micon sized...not grit. used to use rouge, but there are better compounds not so messy.