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Thread: Another color balance question...

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    Default Another color balance question...

    Yet another "what-if" color balance question comes to mind, now that some custom dischros are getting ready to make the scene -

    When combining red (660nm & 635 nm) through the dichro, what becomes the new target percentages you want to use for each RGB wavelength to appproximate a good color balance?

    If I don't quit thinking about "upgrades", I'll never get this thing built...
    RR

    Metrologic HeNe 3.3mw Modulated laser, 2 Radio Shack motors, and a broken mirror.
    1979.
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    Quote Originally Posted by Stuka View Post
    Yet another "what-if" color balance question comes to mind, now that some custom dischros are getting ready to make the scene -

    When combining red (660nm & 635 nm) through the dichro, what becomes the new target percentages you want to use for each RGB wavelength to appproximate a good color balance?

    If I don't quit thinking about "upgrades", I'll never get this thing built...
    A lot of math, actually. You pick a starting value of one wavelength and work from there, and it becomes algebra after that. There is no defined RATIO, this starts approaching art.
    You'd go over to the CIE chart, define a triangle of colors that you want to have in your palette and work from there. Ie things are defined in terms of color temperature, or illuminants. So you want a 4500 Kelvin orange white? a 5500 Kelvin tungsten lamp White or a 6200 Kelvin blue white? Do you want to have a Illuminant C spectrum, or the spectrum designed for NTSC or ATSC television?

    ie what final product do you want? And how much power do you have in one source at what wavelenght? what do you have in the second source? And are you using 440 or 473 or 488 for blue?

    In the olden days we designed for excess red or excess green gas lasers, and lived with what we got, so there is little published about how to do this for laser display.

    So tell me what you want in terms of color temerature or standard illuminants and what you got laser wise. Then we will work out somemath here in the forums over the next few days, and DR Lava can check my math ! There is NO fixed, defined ratio. And you are bound within the triangle, ie mixing 633 with 650 doesnt get you 620. We may need to know the area of the image you want scanned too.

    So what do you got and what do you want?
    Steve Roberts
    Last edited by mixedgas; 09-22-2008 at 06:50.

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    Quote Originally Posted by Stuka View Post
    Yet another "what-if" color balance question comes to mind, now that some custom dischros are getting ready to make the scene -

    When combining red (660nm & 635 nm) through the dichro, what becomes the new target percentages you want to use for each RGB wavelength to appproximate a good color balance?

    If I don't quit thinking about "upgrades", I'll never get this thing built...
    A lot of math, actually. You pick a starting value of one wavelength and work from there, and it becomes algebra after that. There is no defined RATIO, this starts approaching art.
    You'd go over to the CIE chart, define a triangle of colors that you want to have in your palette and work from there. Ie things are defined in terms of color temperature, or illuminants. So you want a 4500 Kelvin orange white? a 5500 Kelvin tungsten lamp White or a 6200 Kelvin blue white? Do you to have a Illuminant C spectrum, or the spectrum designed for NTSC or ATSC television,

    ie what final product do you want? And how much power do you have in one source at what wavelenght? what do you have in the second source? And are you using 440 or 473 or 488 for blue?

    In the olden days we designed for excess red or excess green gas lasers, and lived with what we got, so there is little published about how to do this for laser display.

    So tell me what you want and what you got! There is NO fixed, defined ratio.

    Steve Roberts

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    In may particular case, I have approx 400 mw of 532nm, 400 mw of 660nm, and around 120 mw of 473 nm. I know I currently don't have near enough blue without coming way down in the green power as it is, so I'm really wondering about 2 potential additions:

    * How much 635nm could be dichro-mixed with the 660nm for a good RG mix with the 532nm.

    * How much additional 473nm would be needed to white balance both my current setup, and with the additional 635nm red.

    It probably goes without saying, the ultimate goal would be to use all the lasers cranked as high as possible - love those bright overhead multicolor beam shots!!

    Thanks!

    Randy
    RR

    Metrologic HeNe 3.3mw Modulated laser, 2 Radio Shack motors, and a broken mirror.
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    for a cheap approximation, you could use a factor of 3 difference between the reds
    Using Carol Seidel's (a skilled optics engineer, worked for lexel) ratios, you'd
    use 4.6 -1-2.6 for RGB based on ion red and green

    you've got 400 mW of green , 440 of red, so you'd want the equavalent of 1,800 mW of KR red. KR red is 65% 647, the balence 676 in radiometric power. So I'd imagine

    lets guess that the combined diode red is gonna be 4X brighter then the 676/647 combo

    1800 = 4X+ 440
    1800-440 = 1360
    1360/4=340 mW

    So I'd say adding 2 combined 150 mW 633s and you really rock for rRgb with 400 mW of green. In reality its gonna take me a another whole day to do the real math. we'll see how wrong my guess is. Its probably low. Hang in there.

    The real problem is during a show, are you using photopic, mesoptic, or scotopic vision?
    The curves shift around depending on how dark adapated you are and the size of the image and if its beams or graphics. And I dont know.

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    Wink

    Nice of you to muddy the waters up there Randy... I say double your red with 635ish and add 3x you blue... F it, 6x your curent blue with a 445nm blue.
    Love, peace, and grease,

    allthat... aka: aaron@pangolin

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    Quote Originally Posted by allthatwhichis View Post
    Nice of you to muddy the waters up there Randy... I say double your red with 635ish and add 3x you blue... F it, 6x your curent blue with a 445nm blue.
    Yeah, leave it to me to complicate things!!

    OK, I'll admit it - figuring out a true mathematical color balance gives me a headache, and I'm not even the one that did the math!!

    Thanks for your input, Mixedgas!

    I was kind of leaning in the same ball park with the amount of 635 red I might try to add. The blue, however, is going to be another story, to be revisited when I claim my winning lottery ticket!
    RR

    Metrologic HeNe 3.3mw Modulated laser, 2 Radio Shack motors, and a broken mirror.
    1979.
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    Quote Originally Posted by Stuka View Post
    Yeah, leave it to me to complicate things!!

    OK, I'll admit it - figuring out a true mathematical color balance gives me a headache, and I'm not even the one that did the math!!

    Thanks for your input, Mixedgas!

    I was kind of leaning in the same ball park with the amount of 635 red I might try to add. The blue, however, is going to be another story, to be revisited when I claim my winning lottery ticket!
    Hey Randy

    I'm glad *you* asked the question as I didn't want to make myself look stupid

    As you know, i'm going down the same route of wanting to mix some 635/637 or 640 with my dual Maxyz using one of the custom dichro's, I also want to add some nice 445nm blue.

    So, thanks again for asking the question, although i have to confess to not really understanding Steve (Brain the size of a planet) Robert's answer

    Jem
    Quote: "There is a theory which states that if ever, for any reason, anyone discovers what exactly the Universe is for and why it is here it will instantly disappear and be replaced by something even more bizarre and inexplicable. There is another that states that this has already happened.... Douglas Adams 1952 - 2001

  9. #9
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    I was kind of leaning in the same ball park with the amount of 635 red I might try to add. The blue, however, is going to be another story, to be revisited when I claim my winning lottery ticket![/QUOTE]

    A little clarification on rRgb.

    the 1800 mW came from 4.2 times the green power he already has per Carol's numbers (may she be retired someplace nice!) But that numer is for a odd mix of 647 and 676 that ion reds emit, not the mix from 635 and 658 which will by both being shorter, be somewhat brighter brightness. The question is how much.
    We know he will be happy with 2.6 x 440 = 800 mW of blue, and actually with less then that, since Carol's numbers are for a nasty mix of 488 cyan and 477, not the true deep 472 blue.

    I'm not done thinking about it , its caused me a headache, and just asked two of my fellow serious professional optix eggheads for help. That was a educated guess. The real answer probably needs a spreadsheet to compute. Somebody send me a hospital grade pain reliver FEDEX. Thats a tough one. I'll probably be working on that in background processing for a week. Even then folks will argue over the assumptions used to make the answer.

    I say we find the real numbers and equations and pressure James Lehman into writing a standalone color calc. All in favor shout argh! ?

    Steve
    Last edited by mixedgas; 09-23-2008 at 08:37.

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    Quote Originally Posted by mixedgas View Post
    ...

    I say we find the real numbers and equations and pressure James Lehman into writing a standalone color calc. All in favor shout argh! ?

    Steve
    I knew you were trouble the day I met you...

    No more math headaches-
    if the resulting beams and graphics are enough to get a resounding "Dude !!" response or two from the audience, that's good enough for me!!
    RR

    Metrologic HeNe 3.3mw Modulated laser, 2 Radio Shack motors, and a broken mirror.
    1979.
    Sweet.....

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