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Thread: doing raster laser graphics

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    Default doing raster laser graphics

    You make it seem so complicated you discourage me from trying. if that was the point, it worked
    Last edited by ghosttrain; 04-24-2016 at 03:57.

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    I guess it uses MEMS scanners with AOM blanking per laser module explaining the steep price... I'm not sure though!

    Stacking is possible but most software only supports 1 realtime raster scan at a time... It is possible with beyond *or could be* using many "also to zones and then splitting it up".
    But very costly using galvos on top of the need to match all the beam specs of each projector and it would also be setup hell.

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    Those who are ignorant of laser video history seem doomed to repeat it.
    ~
    Having seen the Russian system in person, in its early stages before it was color, you need to know two things. It is not MEMS scanning, that cannot handle the power levels involved. It is acousto-optic scanning. Second it has a color gamut and potential peak brightness far beyond anything else out there, limited pretty much only by the source laser power, and 50 grand for it is about right.. In person, its amazing.
    ~

    If you want to try, start with a 7.85 KHz CRS resonant scanner from Cambridge... The trick is syncing the video card in the PC with a 15 KHz sine wave from the scanner, and then outputting the video when it is effectively speeding up and slowing down at Horizontal Scan Speed divided by Two. This is called linearization, and its not easy..

    Steve
    Last edited by mixedgas; 03-28-2016 at 08:13.
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    Quote Originally Posted by mixedgas View Post
    ~
    Having seen the Russian system in person, in its early stages before it was color,
    Err.... what was it before it was "color"?
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    • Quote Originally Posted by Bradfo69 View Post
      Err.... what was it before it was "color"?


    Monochrome, 532 Green, and it did 640x480 full rate video back in the 90s. Saw it in Canada on the side of a hotel at a laser conference. Beautiful machine, everyone wanted to buy the US rights to the technology... One of my friends almost did.

    I've seen the insides of the older one. Simple, Beautiful, AO scanning. There is just something about video with a touch of laser speckle...

    Steve
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    @mixedgas, why not simply use polygonal mirrors attached to two servo motors? That seems like an easier way to make it.
    I've seen a similar design in a swept volume volumetric display patent but I can't find it now.[/QUOTE]
    ~
    Air bearing polygon for one axis, galvo for the vertical. Simply because syncing two large rotating masses to within a fractional degree of phase, with such high inertia is borderline impossible without pixel crawl. Again, you buffer the video and sync it to the spinning mass. Said polygons are not cheap.. Its not the immense required speed, its the tiny wobble and you may need faucet following or error correcting lenses. There is a whole book on the subject, and its an interesting read.
    ~
    Next week I'll toss you a few links via PM, all the old work was done with Ion and Dpss lasers, without "brush" scanning of multiple diode beams. Bidirectional scanning was used, however, so was interlace. The other issue is diode divergence, think OPSL..
    ~
    Scientific microscope users now use complex lissajous patterns for the XY scan, its more efficient for them to scan the light that way, without waiting for retraces. I've been in a lab that does that with a femtosecond laser for monitoring interactions in biological tissue. It is really cool to watch one fast resonant scanner with a conventional galvo trace out the patterns.
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    Teaser: http://www.prysm.com/laser-phosphor-display/
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    I have a sample of a safe chemical that changes reflectance when hit by the right pair of cheap lasers, with the right persistence.... I'm NOT talking, but someday... Daylight Laser Graphics... Already tried it one day. Daylight beam shows are not impossible, but that will take a while longer for me to perfect the beam stops.. Besides, they look like classical daytime fireworks, interesting for about all of one minute... Just kidding..
    ~
    Search Doug Dumage Laser Video in Wayback machine, you might be in for a treat if the page is there.
    ~
    There is the famous other "Doug" trick, blend in some small percentage deep green to boost the 647 red into a correct orange for video. Its not true RGB, to play a DVD you have to match the P22 Phosphors used in video for it to look good. A carryover from NTSC/PAL, is the old video color gamut. Doug also used the 482 blue line as mentioned.
    ~
    ~
    Steve
    ~
    ~
    PS, Daytime fireworks, the version without flags on parachutes... https://www.youtube.com/watch?v=F1rtLynfLxw
    Last edited by mixedgas; 03-31-2016 at 06:37.
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