7 ms·
Diffractive Chocolate
- ctenb 2y agohttps://archive.is/Lphsl https://archive.is/Lphsl
- jjtheblunt 2y agowhat the heck are they talking about in the linked article? each color of light travels at a different speed? > White light can be separated into all seven major colors of the complete spectrum or rainbow by using a diffraction grating. The grating separates light into colors as the light passes through the many fine slits of the grating. Each color travels at a different speed and therefore has a different angle of refraction when it hits the grating.
- AdamH12113 2y agoYeah, that's a thing. 3Blue1Brown did a video on it a while back: https://www.3blue1brown.com/lessons/prism https://www.3blue1brown.com/lessons/prism It's part of a larger series that starts here: https://www.3blue1brown.com/lessons/barber-pole-1 https://www.3blue1brown.com/lessons/barber-pole-1
- smegsicle 2y agowhy did you think it happened?
- jjtheblunt 2y agorefraction angles are wavelength dependent, i thought...not the fraction of c by wavelength of photon. from the wikipedia article on dispersive prisms, for example, though i asked above because i remember this from physics at Fermilab in high school. > The refractive index of many materials (such as glass) varies with the wavelength or color of the light used, a phenomenon known as dispersion. This causes light of different colors to be refracted differently and to leave the prism at different angles
- muti 2y agoFrequency is constant, wavelength changes and so does velocity, from wikipedia refractive index > The refractive index, n, can be seen as the factor by which the speed and the wavelength of the radiation are reduced with respect to their vacuum values: the speed of light in a medium is v = c/n, and similarly the wavelength in that medium is λ = λ0/n, where λ0 is the wavelength of that light in vacuum. This implies that vacuum has a refractive index of 1, and assumes that the frequency (f = v/λ) of the wave is not affected by the refractive index.
- jbmchuck 2y agoThey travel c in vacuo but not through different media.
- webstrand 2y agoYeah, the author absolutely confused this with transmission grating which works by transmission rather than reflection.
- kragen 2y agotransmission gratings also do not work by dispersion
- yorwba 2y agoWith a diffraction grating, all colors travel at the same speed, but some light waves reflected off/transmitted through the grating end up taking a longer path to reach the same point in your eye, and depending on the wavelength, that length difference causes constructive or destructive interference, amplifying some colors and suppressing others. Colors traveling at different speeds through a medium is the usual explanation for color separation through refraction, but it doesn't really help for understanding diffraction.
- xutopia 2y agoIt's indeed not correct... but it diffracts so some of the light lands on your eye later because it's angled differently hence the colour change... just guessing. I'm not a physics major.
- dekhn 2y agoYes; a dispersive prism (https://en.wikipedia.org/wiki/Dispersive_prism https://en.wikipedia.org/wiki/Dispersive_prism) is a simple example of this (both prisms and diffraction gratings are used to break light up into its spectrum). The fundamental physical mechanism is known as "dispersion": https://en.wikipedia.org/wiki/Dispersion_(optics) https://en.wikipedia.org/wiki/Dispersion_(optics) The backstory of diffraction gratings is part of the ongoing story of precision. The first ones were created shortly after Newton's use of the prism to demonstrate dispersion, and by the late 1800s, https://en.wikipedia.org/wiki/Henry_Augustus_Rowland https://en.wikipedia.org/wiki/Henry_Augustus_Rowland was quite good at making high quality gratings that were used in astronomy to figure out some of the most fundamental details. They were highly sought after- effectively he was the only person who could make high quality gratings for a while (and he shared them widely). If you really want to go down the rabbithole, see https://en.wikipedia.org/wiki/Dividing_engine https://en.wikipedia.org/wiki/Dividing_engine (fans of the screw cutting lathe will appreciate that the same technology is used) and https://www.edmundoptics.jp/ViewDocument/MKS%20Diffraction%20Grating%20Handbook%20(8th%20edition).pdf https://www.edmundoptics.jp/ViewDocument/MKS%20Diffraction%2... and http://snl.mit.edu/pub/papers/WP/Nanoruler-White-Paper.pdf http://snl.mit.edu/pub/papers/WP/Nanoruler-White-Paper.pdf
- kragen 2y agohowever, diffraction gratings do not use dispersion, so the page is confused this error is not contained in the tech ingredients video the page links; unlike, for example, nighthawkinlight, tech ingredients is careful to get the science correct
- dekhn 2y agoDispersion is the name for the process of separating the light into individual frequency components but there is more than one mechanism. The term 'dispersion' to refer to what diffraction gratings do is already well established.
- kragen 2y agousually the term 'dispersion' is contrasted to what diffraction gratings do. 'dispersion' normally refers to the frequency-dependency of phase velocity in a wave medium, which can result in separating waves into separate frequencies but does not always (for example, a pulse train traveling through a one-dimensional dispersive medium is a case of great practical interest). but it's true that from time to time people do use the term 'dispersion' to refer to separating light into individual frequency components with a diffraction grating. it just isn't the normal meaning, and it isn't one i'd seen before
- DavidVoid 2y ago> each color of light travels at a different speed? That is indeed correct when light is not traveling through a vacuum. Refraction occurs because of a change in velocity between mediums, and the refractive index is wavelength-dependant (dispersive) in many mediums.
- jjtheblunt 2y agothanks all for the pointers: they led me to an explanation from Feynman, which I'd not found before. And hadn’t seen in high school. https://www.feynmanlectures.caltech.edu/I_31.html https://www.feynmanlectures.caltech.edu/I_31.html
- aaron695 2y ago[dead]
- zifk 2y agohttps://www.youtube.com/watch?v=UsDnkrDvkBo https://www.youtube.com/watch?v=UsDnkrDvkBo Ben from Applied Science has a good video going over the same topic.
- brcmthrowaway 2y agoDiffraction gratings are amazing. Is it possible to make one with a 3d printer?
- getoffmycase 2y agoYou can order them super cheap and in bulk from a variety of retailers. Ranging from simple toy things to rolls of it
- brcmthrowaway 2y agoLink me?
- jffry 2y agohttps://duckduckgo.com/?q=buy+diffraction+grating+sheets https://duckduckgo.com/?q=buy+diffraction+grating+sheets
- colechristensen 2y agoThe feature size is pretty small for diffraction gratings. There are printer beds that will do the same to the bottom of your print as is done with this chocolate. None of the hobbyist models could get even close. The feature size is somewhere between 1 and 10 micrometers which is a couple of orders of magnitude finer detail than most 3d printers. They are normally manufactured with other methods, but here’s a paper about printing them https://asmedigitalcollection.asme.org/IMECE/proceedings-abstract/IMECE2022/86632/V02AT02A022/1156781 https://asmedigitalcollection.asme.org/IMECE/proceedings-abs... So it’s possible, I’m sure they aren’t the only ones to try it.
- serf 2y agono, not really -- BUT -- you can print onto the top of a grate to apply that surface finish to the bottom of the print. It's a neat thing to do when you're printing phone cases or something similar.
- deadbabe 2y agoWhy haven’t chocolatiers exploited this to make really unique pieces?
- autoexec 2y agoToo busy exploiting trafficked child slaves? https://www.bbc.com/news/world-us-canada-57522186 https://www.bbc.com/news/world-us-canada-57522186 In all seriousness though, this would be pretty cool and I'd love to try it. I suspect that some of the problem is just that companies tend to constantly push to deliver the bare minimum while charging the most. Holographic chocolate would take more money to make and companies are always trying to charge you as much as you're willing to spend for chocolate while giving you the lowest quality/effort product you'll still pay for. While I wouldn't expect to see something like this showing up in the candy aisles of your typical grocery store smaller fancier places will be willing to do it and charge a premium https://www.brunnershop.com/en/Frame-Moulds/Holographic-chocolate-bar.html https://www.brunnershop.com/en/Frame-Moulds/Holographic-choc...
- HelloNurse 2y agoIt isn't a matter of money, it's just too delicate to sell: unless you distribute bonbons or tablets still in their mold, to be cooled and extracted just before eating, even mild heat applies a lowpass filter to micrometer scale surface features instantly and unrecoverably.
- hwayne 2y agoIn my experience, it's three things: 1. You need really good surface contact to get the diffraction on, so you can only really apply it to flat, uncurved surfaces 2. You need to apply it while the chocolate is hardening. If you're using a mold, you cast the chocolate upside-down so only the base is exposed during setting. You can't diffract the part people will actually see. 3. The effect is really fragile. Chocolate melts at around body temperature, so if you hold the piece for too long, the diffraction disappears. I've been able to transport diffractive chocolate in a padded box but don't think I could wrap the chocolate directly.
- femto 2y agoIf you can cast a diffraction grating into chocolate, it should also be possible to cast a reflective hologram. Holding a block of chocolate up to light and seeing a 3D image would be pretty cool.
- hwayne 2y agoI've done this! You can also cut a small square of diffraction grating and put it on top of a hardening chocolate candy (like an enrobed square of ganache) to make decorate a completed chocolate: http://whoisgood.dog/img/chocolate-diffraction-picture.jpg http://whoisgood.dog/img/chocolate-diffraction-picture.jpg Also tip: easiest way to temper a pot of chocolate is with an electric hand-mixer. Wait until it's 32C, mix for fifteen seconds, bam tempered.
- knicholes 2y agoIt's pretty easy to put the chocolate into a tempering machine, push a button, then walk away, too.
- Felomo 2y agoIt's pretty easy to just order the chocolate and just doing nothing yourself... You do understand that a trick is something different than buying a machine for the job right?
- knicholes 2y ago... Using a hand blender is using a machine for a job too, isn't it?
- DiggyJohnson 2y agoGP's point is that responding to an aside about how to do something with a snarky "or you could just buy a dedicated machine" will come across as obnoxious. This should be obvious to you or anyone.
- knicholes 2y agoWhat's obnoxious is someone claiming they have found the easiest way but then refusing to accept an easier way.
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- ma2t 2y agoOne of the things I appreciate about HN is that discussions often acknowledges the pioneers. Way back in the early 1990s Eric Begleiter started Dimensional Foods to commercialize edible holographic technology. He gave a memorable demo at Thinking Machines Corp. where, in addition to rainbows from diffraction sheet molded foods, he showed some simple rendered 3D scenes floating in chocolate illuminated by a slide projector. Very impressive at the time when he broke off a chunk and ate it. The short-term idea was to give a rainbow sheen to breakfast cereals, but I think longer term there was talk of using holograms to distinguish and layer information on medicines. Made quite an impression at the time. https://web.archive.org/web/20150527050715/https://www.nytimes.com/1997/04/02/garden/where-no-candy-has-gone-before-light-as-the-secret-ingredient.html https://web.archive.org/web/20150527050715/https://www.nytim...
- IncreasePosts 2y agoIf you don't mind me asking - what were you up to at Thinking Machines at the time?
- flir 2y agoI tried this in the early 90s off the back of a short article in Scientific American about chocolate holograms which was almost certainly about the same company. It worked, and I think it would have worked a lot better if I knew more about tempering chocolate. It struck me at the time that using holographic foil as a mould would be the natural next step. I've got a vague memory of a chocolate record being made as an art project? The needle abraded the surface so it wasn't really playable more than once.
- rgovostes 2y agoSamy Kamkar, a computer security researcher whose work is discussed on this site, generated some coverage with his iridescent chocolate a few years ago. But the article and HN comments point to prior art. https://news.ycombinator.com/item?id=23128379 https://news.ycombinator.com/item?id=23128379 https://www.nytimes.com/2020/05/21/science/chocolate-irisdescent-rainbow.html?unlocked_article_code=1.zU0.0MLQ.amzQ021MFktA&smid=url-share https://www.nytimes.com/2020/05/21/science/chocolate-irisdes...
- userbinator 2y agoGiven the surprisingly small feature size achievable, small enough to get diffraction, I wonder if anyone has tried making a playable CD out of chocolate or sugar.
- MrLeap 2y agoYou'd need to move the laser and keep the disc stationary I wager, otherwise is it even chocolate anymore if it can stand the forces?
- Felomo 2y agoA vinyl is doable. A CD probably not. The refraction doesn't need to be aligned etc. Putting it on and scanning it perhaps but not a one try it life
- perlgeek 2y agoI like your way of thinking :-) A CD as a reflective coating to distinguish the pits, I don't know if that's mandatory though. Very thin gold foil is edible though (it just passes through the intestines, being chemically inert), so maybe a sugar disc coated with gold could be made to be playable, and still be edible? As for the base material, I'm pretty sure that sugar has the better mechanical properties compared to chocolate. If you get it perfectly round and spin it up slowly, there shouldn't be too large forces acting upon it.
- Modified3019 2y agoYou can also find the same thing naturally in roast beef when you cut against the grain resulting in even microstructures. https://www.mdpi.com/2304-8158/2/4/499 https://www.mdpi.com/2304-8158/2/4/499
- azubinski 2y agoIt is obvious that if you correctly add pieces of something like this to a viscous medium (so that the pieces are on the surface of the medium), you will get a viscous material with a visually observable diffraction effect: https://bartovation.com/product/other-lab-supplies/diffraction-grating-sheets/13500-lines/ https://bartovation.com/product/other-lab-supplies/diffracti... The other thing is unclear: Why gnaw on diffraction sheets? Will this make chocolate taste better? Will this improve your health? It's all very exciting and mysterious.
- lupire 2y agoThe reason to use chocolate is that it is able to form a diffraction grating, so you don't have to eat the plastic.
- ajb 2y agoThis is cool. I wonder how you ensure that your mould is made from food-safe materials. Presumably gratings are usually just cut glass, so that should be okay? They are not part of the usual food-safe supply chain, though. I guess to would be tricky to obtain the proper assurances if you wanted to do this commercially.
- lupire 2y agoA mass producer would simply test the standard materials and verify. Molding is a well understood industrial process.
- tgtweak 2y agoSimilarly they now have diffractive 3d printing "beds" that leave a chromatic layer on the bottom of your 3d prints... https://store.bambulab.com/collections/bambu-build-plates/products/bambu-3d-effect-sheets-combo-with-plate?skr=yes https://store.bambulab.com/collections/bambu-build-plates/pr...