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.
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.
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.
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.
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).
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
This guy always has an unreal amount of engineering lift for hobby videos. A treat to watch every time.
It's a completely different level, he has my favorite combo, incredibly detailed videos with fresh and complex engineering ideas
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.
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.
What a 10x engineer does in his free time
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.
Could this be used to make a diffraction grating on PMMA?
Pity it won't work for chocolate holograms.
Why not?
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.
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).
Colors are from oxide layers and dont create a geometric structure that can be molded. He explains in the video.
I wonder if you could etch the oxide layer away to leave the metal pits.
Because chocolate doesn't form oxides
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.
I thought the oxides were just for color variation. Maybe I misunderstood that part.