7 ms·
The likely cheapest home-made Michelson interferometer
https://web.archive.org/web/20260109203451/https://guille.site/posts/3d-printed-michelson/ https://web.archive.org/web/20260109203451/https://guille.si...
- RationPhantoms 9mo agoSame physics principles used to measure gravitational waves at LIGO (Laser Interferometer Gravitational-Wave Observatory)but just much, much smaller. Very neat!
- touchadinosaur 9mo agoReally cool project. I’ve seen sometimes cheap lab clean outs on ebay which can be cool toys, but this is on a different level.
- LolWolf 9mo agoThanks ! Still need to upload it to Printables etc. Maybe this will finally get my ass a bit more into gear.
- alnwlsn 9mo agoNeat. Perhaps one can use it to see PLA creep in real time. (not a joke, I'd actually like to see that)
- zokier 9mo agoNot creep, but thermal expansion is definitely noticeable with interferometry: https://www.youtube.com/watch?v=vupIq4epCQA https://www.youtube.com/watch?v=vupIq4epCQA
- LolWolf 9mo agoyeah, even breathing nearby this thing (or putting a soldering iron near the paths) will show a visible change!
- LolWolf 9mo agoOh absolutely! I would not actually use this for uhhh, repeatable measurements over any extended period of time! (If that were the case, I'd recommend re-printing it in a slightly more stable material, or just CNC milling the mounts out of aluminum using some of the ~$1-2K aluminum desktop mills and using some aluminum extrusions as the base.)
- bigiain 9mo agoI suspect they'd be fairly cheap to get made at somewhere like JLCCNC. Or maybe get them to 3D print them in metal for you? I wonder if they have enough different metal choices that you could build a thermal expansion compensated version? https://patents.google.com/patent/US8292537B2/en https://patents.google.com/patent/US8292537B2/en
- LolWolf 9mo agoi’d probably just get it milled only if you had the CNC handy, the complexity isn’t enough to justify 3d printing it in metal (probably a decent bit more expensive too!) but at “get it done in JLCCNC” prices I think a thorlabs mount is probably in your future :)
- bigiain 9mo agoI'd be surprised? If you have spare time, I'd be fascinated to see what their website magic quote tool tells you if you just upload your 3d files. Based on other projects I've seen using them I'd guess under $100...
- ge96 9mo agoThat was a cool physics lab I did (disproving ether) and also measuring the speed of light through lucite... other cooler ones like helmholtz coils, wax lens focusing microwaves, measuring gravity, etc... Wish we worked on IMUs, I still need to get down quaternions
- adrian_b 9mo agoI wish that humans were not so easily duped into believing that things for which someone else uses the same name are really the same and things for which someone else uses different names are really different. The Michelson–Morley experiment was indeed very important, but it has not proved in any way the non-existence of ether. It has just proved that the ether does not behave as it was previously supposed, i.e. like the materials with which humans are familiar. It does not matter at all what names are used for it, one may choose to name it "ether", "vacuum", "electromagnetic field", "force field" or anything else, but all the modern physics, since James Clerk Maxwell and William Thomson, is built on the assumption that the space is not empty, but it is completely filled with something that mediates all the interactions between things. Only before the middle of the 19th century, the dominant theories of physics assumed the existence of true vacuum. The existence of true vacuum is possible only in the theories based on action at a distance, like the Newtonian theory of gravity or the electromagnetic theory of Wilhelm Eduard Weber, but not in field-based theories, like the electromagnetic theory of Maxwell or the gravitational theory of Einstein. It is rather shameful for physics that the main result of the Michelson-Morley experiment has been the replacement of the word "ether" by "vacuum", as if a change of name would change the thing to which the name is applied, instead of focusing on a better understanding of the properties of the thing for which the name is used.
- zokier 9mo ago> The two beams (split in the beam splitter—the little rectangle with a diagonal in the center) add or subtract constructively at the output, which yields fringes that are visible to the naked eye. These fringes will move as light from one of the arms of the interferometer takes a longer or shorter path This explanation is bit incomplete. If you align the interferometer perfectly then it should not have any fringes, the fringes indicate that there is some angle between the light beams. If you get the interferometer aligned then the beam intensity varies as function of the difference of beam path lengths.
- LolWolf 9mo agoFor sure! I didn't _quite_ want to get into the mechanics of it (assuming anyone who is interested would just take a peek at the wikipedia or any YT video). But yes :)
- NetMageSCW 9mo agoI kind of wished there were more details around the tension springs and steel rods.
- LolWolf 9mo agowhat type of details would you like to see? happy to add more if helpful!
- bigiain 9mo agoI have a related question, how far are you turning the thumbscrews when making adjustments? I think M3 standard thread pitch is 0.5mm, so to a first approximation that almost 1000 wavelengths (if I have the SI units right in my head, and I'm not 3 orders of magnitude out?). I suspect the left/right and up/down adjustments have as fairly high lever ratio, but I can't imagine you could successfully adjust the in/out distance with any precision (not in the 690nm sense anyway)? Is the in/out distance not important so long as the beams are aligned? Dunno if you've seen it, but there's a great youtube video explaining how the actuators to align the James Webb mirrors work: https://m.youtube.com/watch?v=5MxH1sfJLBQ https://m.youtube.com/watch?v=5MxH1sfJLBQ including a 3D printable version of them: https://www.thingiverse.com/thing:5232214 https://www.thingiverse.com/thing:5232214 "This is a replica of JWST's mirror actuators. Six of these actuators are paired into a hexapod / stewart platform arrangement and used to control 6 degrees of freedom of each mirror segment (tip, tilt, roll, x, y, z translation)."
- LolWolf 9mo agoOoh, great question. Usually fractions (~1/20th?) of a turn for alignment, it’s hard to go below that since the mounts are so small and the springs don’t have the tension to keep it super stable. (This is plenty for such a “coarse” set up like a Michaelson but might not be up to par for more delicate ones. This can be improved very easily but it was enough for this experiment!) If you want to observe something on the outputs, you have to do something like exhale on one of the arms or put a soldering iron near one of them—merely touching one of the screws gives you indiscernible output, even if the mirrors are aligned. Very interesting re: JWT, I will definitely take a peek, thanks !
- CamperBob2 9mo agoOver $3K for a similar setup from Thor Labs (1). Wow, you can buy everything here including the 3D printer for that. Good work! 1: https://www.thorlabs.com/michelson-interferometer-educational-kit?tabName=Overview https://www.thorlabs.com/michelson-interferometer-educationa...
- LolWolf 9mo agoha, thanks! that one has uhh substantially less drift for what it's worth, but reprinting in more stable material would help that a ton (and still be quite cheap!)
- dekhn 9mo agoWith products from a vendor like Thor Labs, you're getting a lot of quality and knowledge built into the system. Mechanical engineers, electrical engineers, optical engineers... all of which means an edu kit like that will train a student to be useful in most grad research labs (which often build their systems out of thor labs components). It sort of depends on what your goal is; personally, I live to see something expensive on Thorlabs, and make a simplified, less accurate, and far cheaper alternative in my home lab. But that's rarely how folks in labs do it- instead, they will focus on getting people to be useful for performing state of the art research, which usually depends on applying hundreds of years of experience to make some tiny marginal improvement, which frequently depends on having extremely precise and accurate gear.
- LolWolf 9mo agoHopefully you enjoyed the post then! I think there's just such a huge middle ground that's missing (for funny historical reasons[1]) between "children's toy" and "lab-grade equipment" especially in optics, which is why I was excited to make this my first foray into making a fully 3d printed "useful-ish" thing that doesn't really exist otherwise. --- [1] This is because most lab equipment was made _in the lab_ back in the 60s or so, and having this technical ability was a huge advantage for many labs. Now, personnel cost/hours are much more expensive relative to equipment, so people will pretty much pay whatever to get lab-grade stuff.
- DoctorOetker 9mo agoyou can go much cheaper if you use a microscope slide or similar as the "beam splitter". Its not 50/50 so the fringe contrast will be lower, but in interferometry one is typically more interested in maintaining the position of a peak or number of peaks traversed... alternatively one can use a more grazing sharper angle of incidence to bring it closer to 50/50 beam splitting, but then the internal reflections become stronger and the setup is no longer a nice orthogonal one (but how often is that really necessary for a task?)
- LolWolf 9mo agoyeah I cheated a little bit, but > Ok, time to confess: I did cheat a little in calling it the “cheapest” Michelson interferometer, since technically even this beam splitter is like 16 USD, but it is very possible to use a microscope slide instead at the cost of some contrast, which will net out to < 20 cents, even at pretty expensive per-unit prices. :)
- observationist 9mo agoHN hug of death, oh no! Wayback machine to the rescue: https://web.archive.org/web/20260109203451/https://guille.site/posts/3d-printed-michelson/ https://web.archive.org/web/20260109203451/https://guille.si... Very cool project!
- LolWolf 9mo agooops! ran out of netlify credits. should be good now !
- echelon 9mo agoThis was really cool. Please do the delayed choice quantum eraser next and post it here!
- LolWolf 9mo agothank you! and ha, that one requires a little more fancy equipment :)
- boothby 9mo agoWikipedia links to an article with a fairly approachable looking setup for that! https://arxiv.org/abs/quant-ph/0501010 https://arxiv.org/abs/quant-ph/0501010
- LolWolf 9mo agoI think getting an electron source and creating a robust-ish adjustable set up is v doable, but is definitely more of a Real Project(TM) than this silly little interferometer :)
- aj7 9mo agoI’m an optomechanical engineer and I’m sorry. I’m not impressed. In a Michelson, the single most important requirement is that the optical path lengths of the two arms do not drift with respect to each other, either in length or angle. Having that path length determined by a fused deposition polymer is about the LAST choice I would make. I have a suggestion. Fused quartz rods are relatively cheap. Buy some 6mm rods and a thin diamond blade to cut them to size. Use the 3D printer to make plate-like parts, ‘replicating’ a cage structure. The polymer parts should be used only for components PERPENDICULAR to the optical path. You could even experiment with using embedded rods to stabilize the plates in various directions. So much of hobbyist activity amounts to a kind of adult coloring or copying. Rather, at your own level, try to be a scientist.
- LolWolf 9mo agoit’s an interferometer with like 5cm arms made for 3 bucks, it’s not made to be anything other than a basic demonstration !
- lutusp 9mo agoNice project! This video: https://www.youtube.com/watch?v=5nBY4Y0bicM https://www.youtube.com/watch?v=5nBY4Y0bicM explains why the original interferometer was designed in the first place: to detect a hypothetical luminiferous ether, before Relativity theory made it unnecessary. It's important to say the original interferometer was much less elegant -- there were no lasers in 1887. But it did have a solid stone "boat" floating in a little lake of mercury. Not making this up.
- versterrie 9mo agoVery neat design. I work with high-end interferometry but really have an itch to build something like this just for fun. I'll go ahead and add a cheap camera (which I already have) in the image plane and hook it up to my interferometry software (wavefrontpro.com) to make it even more fun and useful! :)
- LolWolf 9mo agoSweet thanks! Yes definitely a great extension would be to add a camera in the image plane (alternatively, defocusing the image slightly and using a photodiode would also be fun!)
- realo 9mo agoUse corner cube retroreflectors instead of flat mirrors.