Iridescent Rainbow Chocolate, Just Add Diffraction Grating!

Chocolate plus diffraction grating equals rainbow chocolate

Here’s a great picture from [Jelly & Marshmallows] that shows off the wild effects of melted chocolate poured onto a diffraction grating. A diffraction grating is a kind of optical component whose micro-features act to disperse and scatter light. Diffraction gratings are available as thin plastic film with one side that is chock full of microscopic ridges, and the way light interacts with these ridges results in an iridescent, rainbow effect not unlike that seen on a CD or laserdisc.

It turns out that these micro-ridges can act as a mold, and pouring chocolate over a diffraction grating yields holo-chocolate. These photos from [Jelly & Marshmallows] show this effect off very nicely, but as cool as it is, we do notice that some of the letters seem a wee bit hit-or-miss in how well they picked up the diffraction grating pattern.

Fortunately, we know just what to suggest to take things to the next level. If you want to know more about how exactly this effect can be reliably accomplished, you’ll want to check out our earlier coverage of such delicious optics, which goes into all the nitty-gritty detail one could ever want about getting the best results with either melted sugar, or dark chocolate.

15 thoughts on “Iridescent Rainbow Chocolate, Just Add Diffraction Grating!

  1. If you make a silicone mould with the grating positioned correctly, you can trasfer the effect to the silicone, even cut and join it with outher pieces, and then use that combined silicone mould to cast hundreds of shiny chocolates with a much more refined efffect ;)

    1. David, I’m trying to do something just like that for resin jewelry molds. You seem to know something about this.
      Could I Have your email?

    1. I wonder if there is any equivalent metamaterial effect for taste? I’m assuming it doesn’t affect anything since no chemical has been added, but it would be cool if there was some pattern on the scale of taste buds that created some kind of illusion.

  2. I wonder if the crystal form of the cocoa butter makes a significant difference in its ability to conform to a diffraction grating pattern. Chocolate makers go to great lengths to ensure that it only crystallizes in form V.

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