Optical diffraction patterns made with a MOPA laser engraving machine [video]

https://www.youtube.com/watch?v=RsGHr7dXLuI

by emsign • 9 months ago

166 32 9 months ago

$Preview of Optical diffraction patterns made with a MOPA laser engraving machine [video]$ youtube.com

hnthrowawayacct• 9 months ago

This guy always has an unreal amount of engineering lift for hobby videos. A treat to watch every time.

JKCalhoun• 9 months ago

Yeah, a YouTube treasure. For anyone new to his channel, you have a back log of amazing experiments to binge on.

I believe he works at Alphabet (tangent?)—somewhere in the Bay Area.

quux• 9 months ago

IIRC he works (worked) for Verily, and previously was at Valve working on their VR hardware. He's also mentioned having a business pre-Valve that made MRI safe controllers for users to interact with computers while inside an MRI machine.

ThrowawayTestr2• 9 months ago

What a 10x engineer does in his free time

egeres• 9 months ago

It's a completely different level, he has my favorite combo, incredibly detailed videos with fresh and complex engineering ideas

jayrot• 9 months ago

Also, really the holy grail of YouTubers — he’s not concerned with clicks or retention. He has a day job, he’s not trying to do this full time or make a career out of it. I’ve been following him for years. Legitimately just an insanely smart person doing projects on his own time he thinks are interesting and that he thinks other people might be interested in too. It’s kinda crazy when it’s as simple as that with no ulterior motives or incentives.

mikkupikku• 9 months ago

Pity it won't work for chocolate holograms.

alganet6• 9 months ago

Why not?

ThrowawayTestr2• 9 months ago

Because chocolate doesn't form oxides

rainbowzootsuit• 9 months ago

Colors are from oxide layers and dont create a geometric structure that can be molded. He explains in the video.

Karliss• 9 months ago

The chocolate is mentioned because some time ago people discovered that you can just use a piece of diffraction grating or holographic stickers as mold for molten chocolate and it will transfer the diffraction grating/hologram to chocolate. Now you can buy commercial silicon molds for creating chocolate with holograms, you can also get 3d printer build plates with similar idea. Just reproducing a hologram in DIY environment with easily available household items is unusual, doing it with food items is more amazing. Applied science channel has a video on that as well from few years ago although he wasn't first one to come up with similar idea.

This technique with laser seems to produces the diffraction grating by varying oxide layer thickness not by creating 3d texture so resulting surface is still flat and attempting to use it as mold will not transfer the pattern to chocolate.

The reason many commercially available diffraction gratings have 3d texture (and thus suitable for copying with chocolate) is because stamping a hot piece of metal into plastic is a very cheap way of doing it.

brcmthrowaway• 9 months ago

Could this be used to make a diffraction grating on PMMA?

tecleandor• 9 months ago

I don't think so, but corrections are welcome.

It's also mentioned in another comment and (I think) the video about how it wouldn't work in chocolate. As it works creating oxide layers, not a diffraction structure:

If you try it directly on PMMA it won't create a diffraction structure, but a kinda slightly melted surface. I don't know if etching would be possible with enough precision on PMMA.

If you do it on steel and use it as a mold to pour (?) PMMA, as people do with chocolate and diffraction grates on plastic, there's no structure to transfer.

mjb• 9 months ago

That's much better results than mine!

I notice a similar 'holographic' effect when coloring titanium a couple weeks back, and experimented with getting them dialed in along the same lines as this video. I didn't have nearly as much success, despite the underlying physics being similar. My guess is that the much lower thermal conductivity of titanium causes a lot more smudging than on stainless, which makes the grating effect less pronounced.

One interesting thing I noted with Ti is that satin finished Ti (media blasted with 500 grit glass media) won't take a color from electrocoloring, but will from MOPA laser coloring. Not nearly as nice as polished Ti, but still there. Given that they are such similar processes (growing a set thickness oxide layer), its somewhat surprising to see different results.

I guess I'm going to have to experiment on some polished 304.

kragen6• 9 months ago

Maybe you're melting the metal surface flat before the oxide forms on top of it?

kelseyfrog• 9 months ago

I'm confused by the authors description of holograms and my own understanding. He starts to go down a path of holographic "pixels," but whai I know about holograms is that the holographic image doesn't have such a concept - the image is delocalized.

There have been some successful attempts at handmade holograms[1] that I wonder how the video creator could adapt.

1. http://amasci.com/amateur/holo1.html

somat• 9 months ago

I suspect that the idea is that the simple way to etch a hologram in the surface is to have a set of holographic picture elements(pixels) where each element hologram would get etched for each pixel in the source image.

It also sounds like this was a minor side experiment and found not to work as expected so not much further effort was put into it.

rcxdude• 9 months ago

I think he's thinking like lenticular images which are often described as 'holograms', since the apparent color changes with the viewing angle like with the lenticular images.

neilv• 9 months ago

YouTube wouldn't show me this video using Firefox, even with uBlock Origin disabled:

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But it would show me the video using Chromium, without an account configured.

bayindirh• 9 months ago

Probably it authenticates your browser via the Chrome validation header [0].

Remote attestation, anyone?

[0] https://github.com/dsekz/chrome-x-browser-validation-header

Optical diffraction patterns made with a MOPA laser engraving machine [video]

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