Full color laser TV

Back in 2001, [Helmar] made an awesome monochrome video display out of a red laser pointer and a spinning 18-sided mirror. Blue and green lasers are much less expensive than they were a decade ago, so [Helmar] decided to go full color with his laser projector. (In German, so fire up Chrome or get the Google translation)

The ancient website for [Helmar]‘s green-only projector goes over the principles of operation. A single laser shines onto a multi-faceted polygonal mirror. This is reflected onto another mirror that provides the reflection for each line in a frame of video. Earlier this year, [Helmar] hacked up a red and blue laser to complement the preexisting green laser. The end result is an RGB projector powered by friggin’ lasers.

As far as we can tell, the projector only has composite input; the attached DVD player provides all the signaling for that. Amazingly, [Helmar] didn’t use a microcontroller for the circuitry. All the electronics are simple logic gates. Really amazing if you ask us.

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Ghostly images appear thanks to projections on fog

This wire-frame cube appears to be floating in mid-air because it actually is. This is a project which [Tom] calls a Laminar Flow Fog Screen. He built a device that puts out a faint amount of fog, which the intense light from a projector is able to illuminate. The real trick here is to get a uniformed fog wall, which is where the laminar part comes in. Laminar Flow is a phenomenon where fluids flow in a perfectly parallel stream, not allowing errant portions to introduce turbulence. This is a favorite trick with water.

[Tom's] fog screen starts off with a PC fan to move the air. This airflow is smoothed and guided by a combination of a sponge, and multiple drinking straws. This apparatus is responsible for establishing the laminar flow, as the air picks up fog from an ultrasonic fogger along the way.

The only real problem here is that you want the projector shooting off into infinity. Otherwise, the projection goes right through the fog and displays on the wall, ruining the effect. Outdoor applications are great for this, as long as there’s no air movement to mess with your carefully established fog screen.

You can find a short test clip embedded after the break but there are other videos at the link above.

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RGB laser projector is a jaw-dropping build

We can think of no better way to describe this laser projector project than Epic. [C4r0] is a student at Gdansk University of Technology and he’s been working on this projector for at least a couple of years. It uses several different laser diodes pulled out of DVD burners, Blu-Ray drives, and entertainment equipment (the green diode is from a disco laser).

In order to direct the beams he built a series of brackets that hold dichroic filters which reflect some wavelengths of light while allowing others to pass straight through. Each diode also needs a driver, most of which he built from scratch. And once the hardware has been designed and tested, what does one do with it? If you’re [C4r0] you build it into a money case with professional-looking results.

Don’t miss the video demo after the break. And make sure you have a rag ready to wipe up the drool before you look at his forum post linked above.

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Old-school projector turned digital

Who hasn’t thought about turning a 1950s slide projector into a digital projector? [Matt] did, but unlike most of us, he actually did it.

[Matt]‘s friend [Angus] found an old, single-slide, sans-carousel slide projector in the trash. It’s a wonderful piece of ancient technology with a fabric insulated power cord and bakelite lamp socket. This projector was upcycled to the 21st century by adding a 10 Watt LED and a Nokia 1200 LCD.

For the electronics, [Matt] used an ATmega88 microcontroller. There’s an infrared receiver so the remote from an in-car CD player can be used to advance the slides and turn the projector on and off. The LCD is controlled by a bit of bit-banging from the Mega88, using hard-coded images of Che Guevara, Hendrix, Space Invaders and some old-school Macintosh/Lisa icons. Unlike the screen printed t-shirts at American Apparel, Che is the only authentic image in this project; this projector might have been made after Guevara came to prominence.

With a 10 Watt LED, it’s not the brightest projector on the planet and the picture is a little washed out in a bright room. With dim lighting, it’s a very good project even if the images are static.

Cookie projector uses that dusty film camera of yours

This hack is not for photographers with weak hearts. We’re going to be talking about destroying the body of a Single-Lens Reflex camera. But out of destruction comes something new. A broken camera paired with a flash and functional optics can be used to project light patterns for picture backgrounds.

The hardware is often referred to as a cookie projector, and a commercial unit can cost several hundred dollars. But if you or someone you know has a non-functional film SLR you’re already half way to making your own. Just snap off the back cover, yank out the mirror and shutter, and the bloody part is over. Slap on a lens with a large aperture, create your own slide with the pattern you’d like to see in your images, and affix a flash to the gaping hole on the back of the camera body. The video after the break shows the diy cookie projector hanging out on the flash stand, synchronized with your DSLR flash to add some pizzazz to the photo shoot.

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Lego Technic Super 8 movie projector

lego_super_8

It always blows our mind to see the things that people dream up when playing with Lego. Given enough time, you could likely replicate almost any mechanical device with the right amount and type of blocks.

[Friedemann Wachsmuth] recently wrapped up construction on a very impressive Super-8 movie projector with the help of his friend [Kalle]. The projector is fully functional, and is made completely from Lego aside from the reel spindles, the lens, and the lamp. As you can see in the video below the projector plays the film quite well, and even though it is only lit using an LED flashlight, it’s more than bright enough to get the job done.

The projector boasts automatic film feeding, a 24 fps framerate, as well as fast rewind capabilities – all provided by just two small Lego Technic motors.

You really need to watch the video to appreciate how much work went into this projector – it’s amazing.

[via RetroThing]

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Interactive sun exhibit uses 3D projection screen and Kinect

A few common components come together to make this interactive museum exhibit that teaches about the sun (translated). It uses three main physical components to pull this off. The first is a custom projection surface. It’s a hemisphere of the sun with a slice cut out of it. This is presumably coated with the paint you’d use to turn a wall into a projection surface. Software translates a projected image to map correctly on the topographic surface, resulting in what you see above, with a Kinect for user input.

Take a look at the video embedded after the break to see how the exhibit works. It instructs patrons to stand on a pair of footprint markers on the floor. This positions them at the proper range from a Kinect depth camera, which translates their outline into cursor commands. By moving a hand around they can explore the different parts of the sun.

We’re in love with how easy this type of interaction is becoming. Granted, there’s a fair amount of work that goes into to the coding for the project, but the physical build is quick and relatively inexpensive.

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