Huygens Optics - 2022-04-18
The second video in the series about manufacturing a small solid telescope. Time to make my hands dirty while doing artisanal stuff. CONTENTS: 0:00 Intro 0:46 The monolithic version of the Cassegrain 2:23 About baffles and stray light 3:18 Drilling the glass core 6:00 Radius milling the glass surfaces 9:35 Calculating the Best Fit Sphere in Excel 13:52 Drilling baffles 14:23 Using spherometers 15:44 This Beat is Spherotronic 16:31 Rough / fine grinding 18:05 Optical Pitch polishing 20:43 What's next? 22:05 Looking through the uncorrected device 23:34 Thank you! Previous video in this series about the theory of aspherics and optical design:https://www.youtube.com/watch?v=awOvnubFE8M Video on the concept of the monolithic telescope featuring inventor Rik ter Horst: https://www.youtube.com/watch?v=HxwhCmO90UQ Video about radius grinding and the Loh CNC: https://www.youtube.com/watch?v=ahrMrOq_lzc More about the properties of optical pitch: https://www.youtube.com/watch?v=eZx-dUtl5Pw You can support Huygens Optics on Patreon: https://www.patreon.com/huygens_optics Download URL for zip-file containing the example MS Excel sheet for doing BFS calculations: https://www.huygensoptics.com/assets/M2_best_fit_sphere_calculation.zip Windows program for calculating milling angle and evaluating spherometer readings: https://www.huygensoptics.com/assets/mirror_calculator_V01.zip Download and use at your own risk. Your virus scanner will probably evaluate this download carefully and scream murder and fire because it is a rarely occurring executable. I used a few short clips from the following Youtube videos, assuming it is covered under "fair use" by placing references to the channels, and links to the corresponding videos in the description. At 15:44, I made an 18 seconds remix of Technotronic's hit "Pump up the Jam". Please enjoy the original hit song by these Belgian techno pioneers: https://www.youtube.com/watch?v=9EcjWd-O4jI At 23:21: Shot take from Edmund Optics video "How an Aspheric Lens is Made": https://www.youtube.com/watch?v=CVDT3u1La6w Did I forget to mention you here? Let me know and I will set things straight.
This series is easily the one I look forward to the most on YouTube. Even if there's no way I could make such a thing, it's still brilliant to learn how it is done.
I agree. It is such a monumental task, that I have the utmost respect for someone who even attempts it, let alone succeeds
I absolutely second this
Hear hear!
That ultra sphereotronic should be a staple of every reputable discotheque in the world.
I am almost insulted there was no link to a soundcloud page
That's the absolute most inappropriate thing I've ever heard anyone say, ever.
Discos still exist!?
@Rat i think they are called MP3otheques Now but the concept is similar
Been looking forward to part 2, can't wait for more! As an engineer, I find these technical deep-dives very interesting. Like last episode, please don't shy away from the maths, there's not enough technical content like this on youtube!
Thanks for this comment. I'm often in doubt about whether my video's are not too niche and technical. But I guess in this case it's partly what attracts a large fraction of the viewers.
@Huygens Optics Possibly make the technical asides clear sections and note timestamps to skip them for uninterested viewers?
@Bachaddict Similar to how CuriousMarc does his elevator music technical interludes?
@Huygens Optics Viewers who don't care for the math can easily skip it. Everyone who appreciates the math cannot easily (or at all) watch the sections if they're left out.
@Huygens Optics I think you shouldn't hold back on the technical aspects, as long as they're of interest to you.
The 15:45 moment caught me off guard. Thanks for sharing your process with so much detail and fun bits. It makes it twice as enjoyable.
I’m looking up OLED PC monitors on Amazonion and this video pops up. Coincidence…..I think not.
I'm so damn happy that the original monolithic telescope video managed to get snagged by the algorithm. Without that I probably still would have no idea that this channel existed, and considering the amount of enjoyment I've gotten from watching these videos that would have been a shame. Your sense of humor is super on point, and many things in the presentation remind me of Techmoan, and I've always been interested in physics of all kinds, and the practical side of optics especially was always kind of dark art. It's easy to look at formulas and do calculations, and advanced computer controlled machinery can of course do wondrous things, but that's not how optics were developed originally. Seeing someone actually talking about and going through the physical process of making something by hand down to accuracies of tens of nanometers is just damn fascinating.
This series takes the genre of ”interesting step-by-step tutorials with no chance in hell of you actually doing it yourself” to a whole new level.
We know you won’t build that cool shelf, ever, Jake. So why not fantasise about building your own non-spherical lens to view stars with?
But hey if I run out of hobby ideas in about 10 years, I'm gonna have a banger go-to idea
I thought that about his Round Spirit-Level a Year ago...
well, im grinding one right now myselfe :P
@T1g3rch3n You go man, good luck :D
LOL I was thinking the same thing as I watched.
Absolutely brilliant video.
I studied optical engineering in the 90s, but ended up doing mostly software. I love seeing the "small workshop" approach to manufacturing such devices.
Keep up the great work!
Excellent work! I helped build the DKIST telescope on Maui, then worked at SpaceX and now I run the machine shop for Space Tango making science experiments for low earth orbit. You’ve inspired me to up my game.
Amazing how much we can achieve when daring to step outside the box we put ourselves in.
As we often joked while working in wind tunnels: "this isn't rocket science -- oh, wait it actually is".
Awesome, I am currently working on a project utilizing a space tango cubelab as the mechanical Container 😃
@N. Heinz Man what a small world.
Oh man this is so satisfying to watch!
As a technic nerd myself, I could watch you all day.
Thank you for sharing this!
What an absolutely spectacular series. I cannot wait for the next one
Not that long ago I was involved with redesigning the baffles for a 2 degree field of view 2.5 m telescope. It's not easy to baffle a telescope with this large a field and it required a baffle around the secondary, the hole in the primary, and third "floating" baffle in between. The Baffling could have been done with just a primary and secondary baffle but this would have greatly increased the obstruction, along with other difficulties.
A light path was found that I was not initially expecting that required an addition to the primary baffle. This involved a bounce off the ID of the primary that was "shaded" by the secondary mirror, up to the secondary and down to the focal surface. It might have been a path that involved primary-secondary-primary-secondary-focus. Lots of bounces. It was a small effect but could be calculated. It was eliminated by just blocking the ID of the primary out to the diameter of the secondary, less the field of view. In your case this could probably be done by just not coating the primary all the way to the ID of the cored out area for the primary baffle. Probably such a small effect that it would never be noticed if it happens at all in your optical design.
Great work and very interesting.
Huygen, I love your videos. Your type of change is what makes YouTube and the internet such an amazing place - sharing really interesting stuff with each other. No matter the length, I’m glued to your videos. The articulation of the concepts are fantastic and the practical side is wonderful to see! Thank you for your hard work making these videos, I truly appreciate them.
Hello Jeroen. YouTube offered your works for viewing. I am pleasantly surprised that optics interests the minds of people in your country (the Netherlands). Unfortunately, in our difficult times in my country it is already very difficult to continue working on the creation of optical devices. But I want to shake your hand and wish you success in further conquering the peaks.
I worked for a company called Vickers instruments in the 90's who made microscopes, but by the time I started all the in house optics had finished and I really wanted to see how this was done. I hope you have some young apprentices that you can pass this knowledge onto, as your teaching skills are as impressive as your knowledge.
Impressive results, even with the aberrations! Looking forward to more
Wow! The engineering and labor behind these devices continues to amaze! Great work!
How the hell can you process all of that info? You must be a genius. You learned all of that math, science, languages even, can even write programs! Incredible. If I could only tap into 10% of that kind of potential... Some people "got it", and others simply don't. I guess we can only play the cards we are dealt.
Can't wait for part 3. Really interesting.
This is incredible! I had no idea there was all these custom techniques for polishing.
Beautiful dance moves!! :) Excellent video as always.
I'm grinding and polishing my (very amateur) telescope mirror and was very happy to see how the mirror making process is made at a professional level.
Thank you.
your videos are insane, thanks for making them
Everything in this series is fascinating, and I look forward to learning more about this in the next instalment! It is astonishing what dedication and knowledge can accomplish.
Brilliant! Super interesting and usefull, thank you SO much for your knowledge and sharing efforts! Can't wait to see next episodes. Personally working in a precision metrology field and find your results amazing.
This is some exquisite engineering! Thank you for sharing the genius approach to making these incredible optics!
Such an amazing project. Thanks for bringing us along with you!
I'm honored to be able to witness this process (this is my second video watched. First one being Part-1) and in awe of your skills and technical equipment. Thanks for sharing. This is exactly what elevates YouTube above the ordinary and makes watching it worthwhile in the long run.
Learning and expanding the Horizon. Thrilling.
Amazing video as always, it's midnight here and I still put on my glasses and booted the laptop to watch it, love the balance of technical, showing the real challenges rather than the finished product, and humour. Yes I'd be interested in maths deep dive / zemax, but I think it's wise to keep it streamlined as you have so it doesn't turn off a semi-technical or non-technical audience, can always make a deep dive video or second channel (to not hurt your priority in the algorithm with a potentially lower-engagement video).
I've worked on some micro high-precision optics myself, and I'm surprised that you're using spherometers of any ultimateness once you're sub 50 micron. With parts that small, it is near impossible to achieve accurate measurement with no flexing of the glass or substrate, and then the adhesive is either flexible and soft, or hard and scratching, both which hurt your results. And then you start to run into problems of different pockets of slightly different densities in the glass creating different distortions, somewhat based on temperature, and so all you can hope to get to is 'mathematically perfect', which may not correlate to optically perfect below f4.
Is there any reason you wouldn't make an interferometer-style checking apparatus, akin to schlieren imaging? I know that means you have to keep removing compound, but that can be automated with a high pressure distilled water wash, and then you're checking the results in the optical domain, where results are quantifiable in more metrics, and with results that are more directly relevant to the end product? Even having a 4k monitor imaged on to a screen with 20MP camera would probably be sufficient if combined with aperture control. Can be a normal 'camera obscura' style, or you can get fancy and use a 4F correlator setup (provides better linearity to the results you measure vs material removal location estimation).
My bet is that stopped down this lens will come together wonderfully, but wide open is going to impossible in BK7 with cerium. I'd think through how to make a temporary aperture for measurements - silver laid down in concentric rings, tiny gaps, then you can vaporise them with high-current low voltage (thermals could be risky, glass has to be preheated), or just reclaim the silver using an anodic cotton tip with an electrolyte that can accept the silver only upon high voltage application to that ring. And don't limit it to a simulation of a normal lens aperture, it allows you to test bands of the lens and chase down sources of imprecision, so I'd start with testing the peripheries and remove reflector from the inside first. In fact, to speed up tests you could actually utilise the 5% reflection of the uncoated glass boundry, masking off lost light externally, but then you can make a series of rods of the same glass with roughly the same inverse curvature on one end, and a sharp angle on the other, in increasing diameters representing the F-stops going F5.6, F4, F2.8, etc, glued with a water soluble low strength Norland optical adhesive to the lens, and then you black paint the furthest out half of the rod to absorb all transmitted light (100% loss waveguide). The glue if it matches the OD of your glass will mean the rods only need to be roughly in the right shape. Then testing is a breeze, modern high ISO cameras can deal with the reduced light output even if it was down to 1%, and the results would be representative of what would be achieved with sputtered mirror without having to redo the coating so often.
I think you'll find that akin to the contrast lost in a fresnel lens from the percentage of surface area taken up by diffraction points, your lens has considerable diffraction point area I think, not simple to 'black paint' out because the boundary of course creates new areas of diffraction. I would test the impact of this by double masking the incoming light at 5cm and 10cm from the lens, so that the light only falls upon the non-sharp-radiused parts of the glass. Also the black paint you use can have a dramatic difference with how much TIR style reflection happens on the peripheries, and how much is absorbed - normally I paint an ordinary household drinking glass on the outside, then see how much light escapes when illuminated from within with a torch or laser - can fill with water or oil to minimise reflections of the internal glass boundry. Most black paints when they dry do not perfectly adhere to the glass, and the tiny pockets of gaps that emerge turn a 97% black paint into more like 92%, because they are almost always designed to be darkest on the non-substrate air side. Especially true of 'vantablack' or any black that relies on surface structure to cause light to bounce multiple times between the 'skyscrapers'. The 'skyscraper' effect can be reproduced by the right paint combined with 'roughing up' the painted areas.
They are hazardous to work with, but acids that work similarly to hydrofluoric acid (very low molarity, highly localised, neutralizing agent constantly applied) to get past the sub-micron cracking while polishing issue where its critical on the periphery might be worth investigating. The right acid for the right glass allows the 'tips' to be preferentially embrittled, and so finer pieces are ablated more from the areas you want with less cracking of the good bits you want to keep (more accurately, you are changing the speed of sound in the tips as you impregnate the glass, and so impedance matching with the bulk glass is decreased, reducing crack propagation by reflecting more of the energy back in to the tips). Sometimes it is necessary to apply a protective non-miscible hydrocarbon that preferentially wets the 'valleys', concentrating the acid to the 'hills, and adding a hydrocarbon removing compound that is embedded in the solid polishing media (so keeping the hydrocarbons constrained to the valleys). You're probably already familiar, but I think you're on your way to acquiring an SPDT machine eventually, but even before then have a look at the patents and the types of glasses used, I think you'll find it relevant to your manual processes also.
Lastly, I know this is jumping the gun a little, but for the final-product mirrors, by using sputtered metal you're missing an opportunity for chromatic aberration correction. With careful controlled application of AR coatings, you can have different wavelengths penetrate into the reflector to different depths, providing a slightly different travel distance or even a slightly different curvature. Again the patents on CHIRP laser processes and multi-wavelength laser cavities are where I think I have read the most relevant material.
Anyway, such a great channel and project, can't wait for future installments.
I’d love to see the response to your comment … I never heard of anti reflective coatings affecting the path length as a function of wavelength, just reflectivity as a function of wavelength. I suppose if the multilayered anti reflective coating that is optimized to pass a particular wavelength is hit with a different wavelength, then the reflections are more likely to be off the top layer, implying the bending of the ray may be closer to the top layer than the middle layer. Another way of saying the same thing is to claim the anti reflective coating has an index of refraction that changes as a function of wavelength. Since the anti reflective coating thickness may be 20 wavelengths long, I see how this would affect chromatic aberration. Also, it implies the index of refraction of the anti reflective coating would change as a function of the angle of the light ray. For perfect optics calculations I would expect this to be addressed (perhaps the magnitude of phase shifts in the wavefront is much less than a tenth wavelength).
@Doug InOrlando I'd love to see a response too, that's my favourite part of youtube, when viewers give back to the channel. Re: wavelength specific coatings, also worth checking out Foveon sensors. While not directly applicable here (absorbs rather than reflects), it is a commercialised product that functions based on penetration depth being related to wavelength.
RP photonics has a great article on 'Bragg mirrors' and although I wouldn't implement their examples (because they are so angle of incidence sensitive, so would change their correction dependent on how close to small aperture / pinhole the device was operated), it shows the key principles.
This is a great thread of comments perhaps even needs its own Reddit page. Hoping to see how HD Raspberry Pi camera w/rpi0 can be integrated. And of course who can step up with automated AI Mfg of monolithic telescope technology. Yes, I know the strong held belief of manual mfg.
@energyideas thanks very much! Don't think he's going to reply, probably threw too many ideas out there, causes the channel creator to have one of these reactions
- I should properly respond to this point by point, I shall press snooze on that mammoth task till I have enough spare time, probably around 2051
- Hmm close but not quite, so I'll either insult their inteligence or come across as unappreciative and alienate other viewers, maybe just ignore it
- Nooo there are some good ideas in there, so now if I acknowledge the comment and implement them, he'll think I'm copying his ideas. Was hoping to patent some of this process, does this comment invalidate all my avenues for protection. Best to shut my eyes
Again nothing to do with this creator, he's probably just really busy, but a trend I've noticed on YouTube
I am a manufacturing engineer that knows a fair bit about metal machining but next to nothing about optics. I feel I was attacked by a tsunami of knowledge and information. I like your style! You just found a new subscriber.
Amazing to see you making one of these. Watching the video you made with Rik really revealed the genius of the design. I have absolutely no plans of making anything like this, but seeing you making one of these objects and providing the theoretical background is truly mesmerising. Giga interessant en hopelijk hou je er een leuke kijker aan over.
15:42
And here I was nerdgasming with all the precious info, and got hit with this gem...
But seriously, I've been in love since part one, with the format full of details about something that I have only dreamt of DIY-ing. Keep up this marvelous job.
At last, my most anticipated video on YouTube. It's great that you include the formulas. Even if I don't work through the numbers myself, the graphical representation is explained. This time, seeing just how you physically grind the correct radii was fascinating. I can't wait for the next one!
Found these videos because I love astronomy and the telescopes that allow my feeble eyes and brain to see and wonder. Traditionally these kind of videos are way too technical for me. That said I’m completely fascinated by these miniature optics and this amazing artisan mixing science, maths and good old hands on skills so we all can see a little more. Thank you
The less parts, the better durability and cheaper production. That's honestly not only a passion project, as some would say, but a very valuable R & D project for optics, indeed like you mentioned sometimes. Very thoughtful design.
I'm a chemist and I understand almost completely nothing about optics, but YouTube just recommended this to me and it was a very interesting to watch. I'm looking forward to the next video.
My favorite is his actual measurements of Dual slit diffraction patterns in 3 dimensions. It provides intuitive insight including surprising real world subtleties. You see exactly what is happening including the lab set up even down to verifying the calibration.
It simply amazes me that there are such experts in whatever field you can think of. You knowledge is truly mind-blowing and you even make it interesting to a complete layman like me.
What an amazing project ! It amazes me how precise something can be made with the human hand and tools, thank you for sharing your knowledge and experience with us !
Thanks for part 2 :) can't wait to see the improved performance in part 3
As a guy constantly using bought optics, I will say - you are just amazing. i am extremely astonished to see such an expertise level in a "home laboratory"
Tremendously interesting! I never knew how optics for scopes and cameras were made until now.
I never did anything optics related myself but this process is super fascinating to watch!
Thank you very much for sharing your curiosity, knowledge and peculiar craftsmanship with us. Can’t wait to see new episode. 🙏🏻
Thank you for this amazing video series! As a master's student in physics and astro, I have never been able to actually delve in to the rich practical aspects of the optics. This series is a goldmine for people like us who love to learn. Keep up amazing work mate!
I was wondering how it would look with the spherical surfaces, thanks for showing! This series is so interesting, your production quality and method of teaching are also top notch imho. Looking forward to episode 3!
Another amazing video in the series! Can't wait for the next one. Content that goes into the technical details and the math like this is really rare on youtube, but the amazing details are what make these videos so good.
Love the videos and the deep dive nature of your presentation style. Too bad YouTube doesn’t have a super like button like Netflix is trying out 👍👍
Videos such as this are what make YouTube great. Can't wait to dive deeper in the next one!
Excellent work, and thanks for letting us have a look through it! I am captivated by this idea of monolithic telescopes.
This is amazing in every aspect - explaining and craftsmanship. Much respect to you, Sir.
This is mind blowing, real engineer in action. Cool to see such content.
Stuff Made Here - 2022-04-19
Wow, incredible project. Thanks for sharing your knowledge and experience so clearly!
4n 2earth - 2022-04-19
And reflectively!
Evidently the life of an optical expert is kind of a grind....
Hydrazine1000 - 2022-04-19
@4n 2earth But it polishes up nicely! 😃
1.5x playback everything - thank me later - 2022-04-19
@Hydrazine1000 @4n 2earth - goddemit you guys, god demmit!!!=)
Andy - 2022-04-22
As I was watching I thought .. 'SMH would love this guy'.
Mason Edwards - 2022-04-24
Now I'm wondering how you could integrate a "Wife Mode" into a telescope.