Volumetric Display Looks Like A DaVinci Sketch

This volumetric display really shows a lot of potential. And it has just the right balance of simplicity and ingenuity. The rig is being developed by [Michel David] and involves a screen shaped like a helix, and a laser which shines through an optical filter disk.

The moving parts of the device are mounted on the same shaft, which is spun by a belt system connected to a Dremel tool. Since the screen and the information disc are mounted on the same shaft, one part of the synchronization process is already taken care of. You can see the separate stand for the projector, which is a laser in this case but is designed to work with other light sources as well. Since the projection surface is moving towards and away from the projector, a laser is preferrable because of focus issues. Unfortunately [Michel] has been having some issues with switching the diode at high enough frequencies. Still, we think the results in the clip after the break are marvelous.

As far as hardware is concerned, this is a lot simpler than trying to spin a large LED matrix.

24 thoughts on “Volumetric Display Looks Like A DaVinci Sketch

  1. His real problem is that he’s using a green laser. It is not possible to switch Nd based DPSS lasers very fast because of the long upper-state lifetime of Nd. If he switched to a blue or red direct-injection diode laser it would work much better, as they have a very short upper-state lifetime.

    1. Yes it is a line……

      But that is how great things come about…. bit by bit

      We didn’t all whinge and moan that TV didn’t have 1080p quality when it was first invented.

      A good simple attempt at getting a 3-dimensional floating display.

      1. When TV was invented, it actually did have 1080p quality, although in black and white, but that’s besides the point. The French made a 1042 line television, but initially chose a 819 line standard, and then adopted the 625 line standard with the rest of Europe.

        The reason why the lower standard was chosen was because of transmission problems. The better picture required more bandwidth, which was scarce because the radio amplifiers at that time couldn’t operate at very high frequencies.

  2. I recall seeing a similar helical display system once on one of those old Discovery Channel tech shows (Next Step? Beyond 2000?).

    That display was oriented vertically, and the application was as a radar display (IIRC) so you would see the relative altitude of objects like planes, in addition to their latitude and longitude.

    Still cool though.

    1. 3D volumetric displays have been around since the early-1960s. A lot of the tech was non-public, and since it didn’t really offer much over a 2D display with user control of viewpoint, was never properly commercialized. It’s just slightly improved scotland mechanical with one more dimension.

      When doing big volume spinning surfaces like this, the chamber needs to be partially-evacuated to get any serious resolution, as resolution depends on speed. There are two styles that I’ve seen: Vector and Raster.

      The vector systems are usually galvo powered; the Raster systems are… well, let me say that the word projection is particularly apt, in terms of math and technology. The tech is 300 years old at this point.

  3. I see lots of promise here, but I agree with previous posters, green laser is the wrong way to go..In combination with red and blue however, there could be some interesting results.

  4. The first recognizable image transmitted with all electronic television was a simple straight line drawn through a layer of soot on a piece of smoked glass.

    Philo Farnsworth had to illuminate it with an arc lamp because he hadn’t yet invented the photomultiplier to go with his image dissector.

    Everyone but Farnsworth and RCA was still mucking about with electromechanical systems. RCA was trying to steal Farnsworth’s inventions instead of paying him royalties.

    RCA’s last ditch attempt to avoid paying patent royalties for the first time in their history* resulted in a “clean room” invention that turned out to be virtually identical to Farnsworth’s invention.

    *Their M.O. was to first make the inventor an offer he couldn’t refuse, one up-front payment and no royalties. If that didn’t work they’d just copy the invention then pour money and lawyers out like water should the inventor try to sue them. Farnsworth just would not go away no matter how much money RCA was willing to spend to screw him out of his patents.

    1. RCA’s guy, Zworkin (I don’t remember the spelling, but he was a hack) had gotten a patent for scanning images with tubes, even though he’d never gotten it to work.

      Farnsworth had had the idea as a kid, while plowing fields in a pattern with a tractor. I’ll skip the long story, but basically Zworkin went to work for RCA and still couldn’t build a working prototype.

      He took a trip to California, and personally visited Farnsworth’s little lab under some pretext. While he was there, he very closely examined the prototypes (which let him see how it had been done) and looked at Farnsworth’s notes.

      Then RCA made it fly. Sort of like Steve Jobs and Xerox Parc, only in reverse. The guy who ran RCA was a serious shark, and he got big before Farnsworth did, even though Farnsworth’s technology was superior in every way.

      In general, money usually overcomes talent like age overcomes youth. If Bill Gate’s family hadn’t been upper crust and connected (Big Lawyer, Socialite Mother), Microsoft would have been just another footnote on the road to the future.

  5. What about using a mirror to reflect the laser? You can use pwm to change the angle of the mirror. All it will have to do is make sure the laser points in a particular direction to mimic the right frame rate. Then it directs the laser to a “blind spot” so it doesn’t shine on the display surface. You can probably achieve a really high frame rate without too much vibration to the unit.

  6. Years ago I read that the US airforce used a similar system to review air manoeuvrings of dogfight training, since you need a 3D representation for that.
    I’m not sure how widespread that was though.

  7. You could use a projector if you used 2 lenses. The first would convex magnify the image (sending out in a cone shape) which would hit another lense (concave) would then redirect the image into a parallel beam the same diamater as the helix. Of course your second lense would need to be at least the same diamater as the helix, which will probably be more expensive.

  8. What you really want for this sort of thing is to have a steady lasing source, and modulate it. That will (help) get rid of any contrast / brightness stability issues. It would also let you use a gas (read: HeNe) laser for much improved resolution.

    Doing that cost-effectively is another matter, as acousto/electro-optic modulator crystals/devices are very expensive.

    1. Fast rotating mirror that you then modulate to affect the laser’s visibility might work perhaps? You only need to deal with the speed of the eye and not the speed of light really when dealing with visual displays.

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