Holography without Lasers: Hand-drawn Holograms (1999)

A kid on Youtube invented the rotating version (scratching complete circles, then turning the plate.) Then an MIT student worked out a way to eliminate the second unwanted image; the pseudoscopic inside-out one. He gave talks on the techniques, find on youtube. Eventually he had an gallery show of his black, rotating scratch-holograms, and a few years later, was hired by various rock bands (and also Disney) to provide rotating scratch-holograms for vinyl re-issues of music. (But no need to remove the second image! That way you get one image down inside the black surface, a second one flying in the air above! Very spiffy and impressive.)

See Youtube playlist of scratch holograms.

https://www.youtube.com/playlist?list=PL60100E8F3572CEB1

Been a fan since I was literally 10 years old. I loved the writeups on Tesla coils. There's also a section on the Bajak Flux Capacitor including a schematic, which I tried to build in the hopes that I could mess with time control.

There was also a heartfelt plea to geeks to not shoot up their school, written in the wake of the Columbine massacre. I really felt that one.

From a quick search:

https://www.instructables.com/The-Scribe-bot-a-Machine-to-Cr...

There’s a commenter on that Instructable who has some examples on his YouTube channel that he made from code he wrote to generate toolpaths (Holocraft): https://youtube.com/@CharlesVanNoland/videos

His blog is here: http://deftware.blogspot.com

The software: https://deftware.myshopify.com/products/holocraft

Guy at MIT made huge numbers of them, using a robot-arm and sharp tool. He worked out an algorithm to interleave the short scratch-segments, so dense intersecting scratches don't ruin the image. His art is now in a mathematics museum. Also, apparently he attempted to change the name of the holograms, pushing the term "Specular Holography" everywhere he could. Deeply silly, since they're not "specular," any more than is any other hologram. They possess a transmission mode and a reflection mode. If you scribe them in clear plastic, then you can either back-paint it black, and illuminate it from the viewers' side, or you can put a light source behind it, and see the same 3D image. The invention isn't inherently "specular."

So, wtf?

Heh, but also, knowing about the history of invention-theft and fights to name new phenomena, I'd earlier listed all the possible names I could imagine. Abrasion holograms, giant-fringe holograms, single-fringe holograms. Paleo holography, caveman holography, prehistoric holograhy, car-hood holograms, Geometrical holograms (geometrical, as opposed to Physical Optics.) Brushed-metal holograms. Chatoyant holograms (same optics as cats-eye gemstones, deep highlights in polished wood and human hair.) So, if you want to take the discovery as your own, you can't use any of my names!

yeah, it's the glint following those curves that form the image (in contrast with the dark areas.) the curve controls how the glint moves wrt your pov.

The light coming out of the scratch-hologram must be coherent. That means, the scratches must be mirrors (like smooth grooves, or bent silver wires, shiny curved spiderwebs.) Normal raster-displays emit incoherent light, and their images are entirely located on the display surface. But make your display out of billions of tiny mirrors, then you can create images which float deep inside the surface. (Or hang in the air, outside the surface.)

IIRC, no, because the edge that makes isn't sharp enough.

it may if you focus it properly. Acrylic melts really well with IR lasers this may be easier they are cheap.

It needs to make a polished groove or smooth surface-divot. Definitely use colored or black plastic, to promote surface-absorption. The real key is to eliminate jaggies. Either your steppers need micron resolution or better, or the laser-sweeping needs adjustable radius (smooth curves, but stepped depth.)

I tell people, if you could play the hologram on a record turntable, the scratches must be silent. No micro-wiggles. The must behave as long, curved mirrors.

Also, back in 1838, Charles Wheatstone reveales the secret of scratch-holograms, but he never followed up on it.

http://amasci.com/amateur/holowhtstn.txt

He did say that the 3D light-effect seen in lathe-turned metal plates led him to discover human stereopsis, to draw stereo pairs, ending up as the stereo camera and stereopticon.

So, that Stereopticon-path of research, it attracted Wheatstone away, and changed the history which mighta-been. We ALMOST had Victorian steampunk holography, a century before lasers existed.

Ever heard of the Rose-engine lathe?

Ever heard of a "ruling engine?" That's how diffraction gratings were made, back in the day. A similar sort of precision machine, equipped with some Jaquard-loom punchcards, could have been turning out giant scratch-hologram masters. (Then stamp out copies, just like vinyl or lac or wax records!)

Someone discovered it all, back in 1979. Built a joystick-controlled motorized scriber-machine. Produced some 3D artwork. Then died without releasing the secret.

1979? 1838? the big question is, did The Masons know about scratch holograms? Encoding secret messages in polished metal surfaces?

Gaze into the works of centuries-old silversmiths, held out under sunlight, see if some little "sandpaper marks" produce tiny words or pictures, floating down inside the metal ...unsuspected by all non-initiates!

Here’s an argument for why these are holograms:

http://amasci.com/amateur/holo3.html

If there's a post about holograms, at least one reply is required to say it's not a true hologram.