The likely cheapest home-made Michelson interferometer

> 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.

Same physics principles used to measure gravitational waves at LIGO (Laser Interferometer Gravitational-Wave Observatory)but just much, much smaller. Very neat!

HN hug of death, oh no!

Wayback machine to the rescue:

https://web.archive.org/web/20260109203451/https://guille.si...

Very cool project!

Neat. Perhaps one can use it to see PLA creep in real time.

(not a joke, I'd actually like to see that)

you 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?)

Very 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! :)

I’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.

Use corner cube retroreflectors instead of flat mirrors.

That 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

Over $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-educationa...

Really cool project. I’ve seen sometimes cheap lab clean outs on ebay which can be cool toys, but this is on a different level.

I kind of wished there were more details around the tension springs and steel rods.

Nice project! This video: 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.