If you watch much science fiction, you know that in the future, there’re plenty of 3D holographic displays. From Princess Leah’s distress call to the Star Trek holodeck, there’s no shortage of computers that can make realistic images. It might not be up to holodeck standards, but [freedscript] created a 3D display for an Arduino using a chopstick, a motor, some paper, and a LASER. Of course, it isn’t actually a hologram, but neither is half the stuff you see on TV (Star Trek’s holographic characters were disturbingly solid for standing waves). The display is a type of volumetric display.
There’s a new display technique that’s making the blog rounds, and like anything that seems like its torn from [George Lucas]’ cutting room floor, it’s getting a lot of attention. It’s a device that can display voxels in midair, forming low-resolution three-dimensional patterns without any screen, any fog machine, or any reflective medium. It’s really the closest thing to the projectors in a holodeck we’ve seen yet, leading a few people to ask how it’s done.
This isn’t the first time we’ve seen something like this. A few years ago. a similar 3D display technology was demonstrated that used a green laser to display tens of thousands of voxels in a display medium. The same company used this technology to draw white voxels in air, without a smoke machine or anything else for the laser beam to reflect off of. We couldn’t grasp how this worked at the time, but with a little bit of research we can find the relevant documentation.
A system like this was first published in 2006, built upon earlier work that only displayed pixels on a 2D plane. The device worked by taking an infrared Nd:YAG laser, and focusing the beam to an extremely small point. At that point, the atmosphere heats up enough to turn into plasma and turns into a bright, if temporary, point of light. With the laser pulsing several hundred times a second, a picture can be built up with these small plasma bursts.
Moving a ball of plasma around in 2D space is rather easy; all you need are a few mirrors. To get a third dimension to projected 3D images, a lens mounted on a linear rail moves back and forth changing the focal length of the optics setup. It’s an extremely impressive optical setup, but simple enough to get the jist of.
Having a device that projects images with balls of plasma leads to another question: how safe is this thing? There’s no mention of how powerful the laser used in this device is, but in every picture of this projector, people are wearing goggles. In the videos – one is available below – there is something that is obviously missing once you notice it: sound. This projector is creating tiny balls of expanding air hundreds of times per second. We don’t know what it sounds like – or if you can hear it at all – but a constant buzz would limit its application as an advertising medium.
As with any state-of-the-art project where we kinda know how it works, there’s a good chance someone with experience in optics could put something like this together. A normal green laser pointer in a water medium would be much safer than an IR YAG laser, but other than that the door is wide open for a replication of this project.
Thanks [Sean] for sending this in.
[Bruce] has created a pretty cool bubble display that is capable of showing recognizable photographs of people. This entire art installation is no slouch at 3-stories tall! This one resides at the Ontario Science Centre in Toronto, Canada. If you are unfamiliar with bubble displays, they consist of several clear vertical tubes filled with a liquid. A pneumatic solenoid valve mounted at the bottom of each tube allows a controlled amount of air to enter the tube at a very specific time. Since the air weighs less than the liquid, the air bubble travels up the tube of liquid. Interesting patterns can be made if these bubbles are timed correctly. This setup uses a Linux-based computer with custom control software to manipulate the valves.
[Bruce] didn’t start off making super-complex bubble displays. This is actually his 3rd go-around and with 96 individual tubes and capable of displaying raster images, it is the most complicated so far. His first creation consisted of 16 tubes, each larger in diameter than the most recent creation. With the larger diameter and less number of tubes came less resolution and the ability to only display simple shapes. Version 2 had twice as many tubes, 32 this time. In addition to doubling the tube quantity [Bruce] also colored the fluid in the tubes, not all the same color but all the colors of the rainbow, from red to violet. Still, this version could not show raster images. It appears to us that the third time’s the charm! Video after the break….
[Alec] just sent us this great project he’s been working on. Converting an antique View-Master from the early 50’s into a modern 3D video player, capable of reading Mini-CDs.
Most View-Masters don’t have much space for tinkering, let alone adding a Raspberry Pi, two displays and a CD drive, so [Alec] really lucked out when he found this model — complete with light and D-cell battery pack. Tons of space! He originally looked into getting some cheap digital photo frame LCDs from China, but soon realized the effort involved with making those work just wouldn’t be worth it, so instead he picked up some 0.9″ OLED displays from Adafruit. He still forgot to check if they had drivers for the Raspberry Pi though, and ended up on another detour of modifying FBTFT drivers to make it all work.
After that headache he got to the fun part — cramming all the hardware inside. He picked up a cheap laptop CD drive off of eBay, and discovered that using the 80MM Mini-CD standard, the discs would just fit inside of the View-Master, sticking out just a little bit, kind of like the original photo wheels!
Quite a bit of fiddling later, he managed to assemble the entire thing in layers, without damaging the external shell of the View-Master. Since it is an antique, it was important for him that his hack be reversible — and for the most part, it is! Stick around after the break to see a short video explanation!
Over the last four years, [Will] and [Gav] have spent their time creating a huge, high-resolution 3D display. The’re just about done with their build, so they decided to offer it up to the Internet in the hopes of people creating new 3D content for their display. They call their project the HoloDome, and it’s the highest resolution volumetric display we’ve ever seen.
The HoloDome operates by spinning a translucent helix around its vertical axis at 20 rotations per second. A pico projector above the helix capable of projecting 1440 frames per second (an amazing device by itself) displays 72 ‘z-axis’ frames for each of the 60 ‘x and y frames’ per second. The result is a 3D display with a 480 * 320 * 72 voxel resolution capable of displaying 20 frames per second.
This isn’t the first time we’ve seen a swept helix used as a volumetric display, but it is by far the highest resolution display of its type in recent memory. [Gav] and [Will] have put their HoloDome up on the Australian crowd-funded site Pozible if you’d like to buy your own, but thankfully the guys have included enough detail on the main site to reconstruct this project.
Check out the video after the break to see the HoloDome in action.
[programing4fun] has been playing around with his Kinect-based 3D display and building a holographic WALL-E controllable with a Windows phone. It’s a ‘kid safe’ version of his Terminator personal assistant that has voice control and support for 3d anaglyph and shutter glasses.
When we saw [programming4fun]’s Kinect hologram setup last summer we were blown away. By tracking a user’s head with a Kinect, [programming] was able to display a 3D image using only a projector. This build was adapted into a 3D multitouch table and real life portals, so we’re glad to see [programming4fun] refining his code and coming up with some really neat builds.
In addition to robotic avatars catering to your every wish, [programming4fun] also put together a rudimentary helicopter flight simulator controlled by tilting cell phone. It’s the same DirectX 9 heli from [programming]’s original build. with the addition of Desert Strike-esque top-down graphics. This might be the future of gaming here, so we’ll keep our eyes out for similar head-tracking 3D builds.
As always, videos after the break.
3D display technology is fairly limited. Most 3D displays out there rely on either prisms refracting light from a normal flat-panel display, or shooting lasers into some sort of space-filling device. A few researchers in Japan went with a more unconventional method of making a 3D display that actually lives up to the promises of the displays seen in Star Wars.
From the coverage of this display we’ve found, the green laser demonstration is a scaled-down version that uses water as the display medium. There’s a short clip that shows a red, green, and blue laser projecting a few white voxels into mid-air. The video of both these demonstrations is a bit jumpy, but that’s probably because of the difference in frame rate between the display and camera.
We’re not really sure how the “plasma excitations of air molecules with focused beams” actually work, or even how to control 50,000 of these dots at 15 frames per second. If you’ve got any idea how to build one of these guys, leave a note in the comments.