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.)
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.
All in HTML 1.0 written by hand, from Unix shell C, using pico.
When I started, I was getting huge international traffic, from people seeing near-instant page-loading when using 2400 baud dialup. I think classrooms were using it for ESL teaching. Also, huge traffic from the deaf community (any images w/text paragraphs, and ease of speech screenreaders. Unexpectedly this put me way high on google, when it finally appeared years later.)
Oh, hello. On EE, I'm a CS guy, but I suck at hardware. Programming it's far easier, even ASM. I always wanted to understand the basics of electricity, but everything looks obscure, even with the Ohm's law. Your site helped me.
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
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!
This is cool. It seems like the code to encode the grooves over descending depths from, like, a depth map and an image file would be pretty trivial to write. Just pick random points in 2D representation of the model and vary the radius of the arc based on their depth from camera? I'm wondering... since I know very little about optics or holography... why does this not produce a holographic effect if you just draw those arcs white on black on a monitor? Is it that the light has to be coming from a separate source as a reflection or transparency?
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.)
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.
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.
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!
Credit-card security holograms ...not true holograms either. Right? They need no monochromatic illumination. And they don't employ any interference in order to produce their 3d images.
That's the whole trick, really. "Scratch holograms" employ exactly the same physics as Benton Rainbow holograms. Both store phase information, and both require coherent illumination, but neither one is based on diffraction (that's why they can still work, even with a white light source.) If you make a Benton white-light hologram, then instead make the "diffraction fringes" about 1mm apart, the hologram STILL WORKS. "Scratch holograms" are just Rainbow holograms where the fringe-spacing is enormous.
So, if credit-card Rainbow Holograms are real holograms, Benton white-light holograms are real holograms, then to be consistent, we're forced to admit that scratch-holograms are holograms. (Besides, they create unwanted pseudoscopic images, and required spatially-coherent illumination, same limits encountered with any true hologram.)
https://www.mentalfloss.com/article/92553/watch-vinyl-record...