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But it would show me the video using Chromium, without an account configured.
I believe he works at Alphabet (tangent?)—somewhere in the Bay Area.
There have been some successful attempts at handmade holograms[1] that I wonder how the video creator could adapt.
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.
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.
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.
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).
Instead, you could choose a different metal whose oxides are easy to etch. Magnesium is probably the extreme case here, with an oxide that instantly vanishes in the weakest of acids, but if someone gave me a US$7000 fiber laser, I would try to keep the laser beam away from thin pieces of magnesium. But mild steel, for example, forms oxides that etch pretty easily with acids. I think copper oxides also etch easily with either acids or bases, too, and the copper itself is more resistant to etching.
Really, though, if you're molding silicone or chocolate, you don't need the high strength, flexibility, conductivity, etc., of metals. Maybe etch your grating into a material chosen for other properties. Glass, for example, is perfectly isotropic and has no grain structure to introduce into your cuts, and it has a low TCE. It sticks to silicone, but not to chocolate. Fused quartz is a glass with a near-zero TCE. I assume but don't know that the MOPA laser can ablate the glass surface.
Other amorphous solids might be more amenable to easy laser shaping and not stick to silicone. Sugar glass, for example.
Otherwise, it's skim an edible oxide layer over the chocolate to etch.
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.