[HN Gopher] Optical diffraction patterns made with a MOPA laser ...
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Optical diffraction patterns made with a MOPA laser engraving
machine [video]
Author : emsign
Score : 99 points
Date : 2025-10-14 07:09 UTC (6 days ago)
(HTM) web link (www.youtube.com)
(TXT) w3m dump (www.youtube.com)
| hnthrowawayacct wrote:
| This guy always has an unreal amount of engineering lift for
| hobby videos. A treat to watch every time.
| JKCalhoun wrote:
| 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 wrote:
| 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.
| ThrowawayTestr wrote:
| What a 10x engineer does in his free time
| egeres wrote:
| It's a completely different level, he has my favorite combo,
| incredibly detailed videos with fresh and complex engineering
| ideas
| mikkupikku wrote:
| Pity it won't work for chocolate holograms.
| alganet wrote:
| Why not?
| ThrowawayTestr wrote:
| Because chocolate doesn't form oxides
| ggm-at-algebras wrote:
| You need a mechanism which forms interference fringes.
| Chocolate blooms, so you might be able to etch the bloom.
|
| Otherwise, it's skim an edible oxide layer over the
| chocolate to etch.
| alganet wrote:
| I thought the oxides were just for color variation. Maybe I
| misunderstood that part.
| rainbowzootsuit wrote:
| Colors are from oxide layers and dont create a geometric
| structure that can be molded. He explains in the video.
| ginko wrote:
| I wonder if you could etch the oxide layer away to leave
| the metal pits.
| Karliss wrote:
| 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.
| alganet wrote:
| Again (see my other comment in the thread), I thought the
| oxides were just for color variation and there was depth
| changes that could be used for a mold.
|
| Anyway, there are still ways of moving forward with the
| idea. For example, chemically removing the oxide layer to a
| desired thickness sounds feasible. If I were him, I would
| try it (but maybe in another video, as the whole process
| would be a whole different rollercoaster).
| brcmthrowaway wrote:
| Could this be used to make a diffraction grating on PMMA?
| mjb wrote:
| 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.
| kelseyfrog wrote:
| 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
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