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.




23 thoughts on “Full Color Laser TV

  1. I love the ingenuity of hackers, however that kind of build is far beyond anything I could do, which is why I’ve got my eye on a Microvision SHOWWX – a pocket projector which uses an RGB laser setup.

  2. If it doesn’t use a microcontroller, I guess it must be working at full PAL/NTSC resolution. I can certainly see how thats possible – I mean the spinning of the mirror needs to be aligned with the sync pulses, probably by a simple pll and feedback loop, and all is good.

    What I can’t see is how the horizontal scan mirror can spin anywhere near fast enough… Presuming 525 scan lines, 25fps, thats 13,125 Scans per second. Assuming a 12 faceted mirror, thats still a mirror turning at 1000 Hz, or 60,000 rpm – thats in the region of motors used for uranium enrichment, so you can’t easily buy equipment that can do that, and pretty much all consumer bearings will fail well before those speeds…

    So my question is – what mirror setup is used for the horizontal scanning?

    1. According to the details of the youtube video “The laser diode is directly modulated with video signal bandwidth.” so you are right on your first assumption. However, the spinning mirror has more like 60 facets if you watch closely in the video they show the large spinning mirror broken up into segments. I counted 15 on approximately 1/4 of the circumference and that’s how I arrived at the 60 count, but seeing as how PAL uses 25fps, that number is probably doubled to 50 for an interlaced picture.

    2. translated from strahlablenkung link:

      The projector used in the 36-facet polygon mirror, however, comes from another system. – If you believe the stories, it comes from one of the first commercial laser printer from the 80s. More accurate but I can not find out because I got the parts (and the accompanying stories) at the time of various computer-scrap recyclers.

      1. Funny since I was wondering why people didn’t use the assembly from laserprinters more often, even new ones are not that expensive and they have a fast and precisely rotation mirror assembly and a powerful laser in them.
        The lenses are designed for a line though obviously and I’m not sure how fast the whole thing rotates, but seeing the resolution of laserprinters and the speed at which a whole page is done I assume it’s rotating pretty fast.
        Perhaps you could house the whole assembly in a motor controlled platform that scans up and down even?

        Videolink to a laserunit of one: http://www.youtube.com/watch?v=lc9SH_7rEXM

    3. 60,000 rpm is nothing for a small bearing. All sorts of thing have bearings that will handle that like higher end hand held engraving tools, turbo pumps, centrifuges, small turbine engines, and other things.

    4. It would probably complicate things, but you could probably get by with a couple of mirrors. One reflecting into the other, so no mirror has to rotate so fast.
      Not saying it’s done like that, but it’s possible.

  3. With out the DVD player as a source and a fpga instead of most of the control electronics this could be even smaller; but all in all for the parts acquired i think this is a pretty sharp build. Keep it up!

  4. Holy smokes, I love stuff like this.

    Unfortunately the only thing going through my mind right now is….

    What would it take to get component video in? and…

    Let’s see an arcade board hooked up. :)

    I dunno, I got videogames on the brain I guess.

  5. I am close to call it fake, he provides very little details regarding laser modulation, and DPSS lasers are almost impossible to modulate fast enough thanks to optical properties of Nd:YAG lasing medium.

    If he used opto-mechanical modulation, then it might have been freaking expensive, with system cost way higher than boring fullHD projector )

  6. I’ guessing you’d a mighty power laser to get any any useful intensity. a few mW of light spread over a square meter of surface is not much

    ramp up the laser power and if the motor fails you burn a hole in the wall

  7. More lasers, please!

    I’ve been wanting to do this hack for years and have a LaserJet 4mp to do it with but lately got a Toshiba 52 inch DLP TV and found it has a six-sector RGBRGB color wheel so I am putting in a six-sector RGBYCV wheel to expand the gamut to around 140% of NTSC or 95% of theoretical perceivable colors. Software will frame switch standard RGB frames with YCV frames the way you’d switch left and right eyes in stereo with specs. Since the DLP is capable of such high binary frame rates, with some loss of color resolution I might be able to demo a stereo TV with 95% of perceivable gamut using specs, but a little graininess in the colors. I don’t know DLP yet. I got the TV *out of the trash*!


    Doug Goncz

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