This is "old Internet" style fun territory (along the same lines as the Tom7 fun, if not quite as deep). I felt that the olive oil + fingerprint + phone screen was a really nice way to illustrate the core concept. Especially clever because it used something common and annoying to help describe how the plotter does its thing.

Before getting further into the article I thought maybe he was going to show how to use the plotter to control the oil smearing technique, which honestly would have been kind of cool.

There are very few TFAs I upvotes before opening TFA. But with such a title, this is one of them...

Holography is such a beautiful and fascinating gateway to physics, and it’s so rare to see true demonstrations of it. Sadly, most people have no idea what it is because of how carelessly the term is thrown around, just like in this article. At least the author admits it and provides some kind of excuse, even if it’s at the end.

Related, "abrasion holography", with great good success for being hand drawn: http://amasci.com/amateur/holo1.html (1995)

Maybe could swap out the pen for a needle?

Something tells me you didn't open the posted link.

I guess I don't know how sharp a pick with an orange handle is from harbor freight, compared to a needle.

In fact, I believe that the article is describing a reinvention of this technique! Just with a plotter on oil rather than a compass on plastic.

He did it on plastic CD cases, not oil. The oil in the beginning of the article was just for explaining the refraction that happens with the ridges in the structure.

Ah, whoops, thanks!

Related: ”Self Reflected” by neuroscientist and artist Gregg Dunn, https://www.sothebys.com/en/articles/self-reflected-a-giant-...

He uses the third dimension to encode time, so that you get an image of the brain that illustrates how signals propagate dynamically between brain regions.

I have a version of this on my wall and its mesmerizing to look at with the right lighting conditions

Beautiful. This needs to be an HN post on its own. Please post. I will upvote.

Steve Mould has a great video on youtube explaining how they work https://www.youtube.com/watch?v=sv-38lwV6vc

It would be interesting to augment the plotter with a Unimorph piezoelectric disk scanner [1], to enable finer movement so lines can be drawn closer together.

[1] https://john-alexander42.github.io/simple-stm-web-page/Disk_...

Chocolate is a good medium for holograms :)

William Beaty had a video of the hands on the car hood. They showed up very detailed some 20 cm under the hood as if people captured inside. Quite the find.

I've made these scratch holograms before with a compass. They're pretty fun, but very far from "real" holograms.