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Thread: In the MIX

  1. #1
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    Default In the MIX

    Hi all. I would like to get a blue which will go well with my red and green, but being a noob, I dont really understand the wavlengths. My reds are maxzy's and my green is CNI.

    So the current specs are :
    100 MW 532 Green
    440 MW 660 Red
    ??? MW ??? Blue

    ...fill in the blanks

    EDIT:: Have the option of upping the Green to more power but would prefere not too

    Graham

  2. #2
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    180 to 200mw of 473nm should do the trick. I am expecting a couple of these in this week. I will post pix.
    You are the only one that can make your dreams come true....and the only one that can stop them...A.M. Dietrich

  3. #3
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    MechEng3, to sell or for your own lasers?
    Graham

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    Default

    Quote Originally Posted by laserLips View Post
    Hi all. I would like to get a blue which will go well with my red and green, but being a noob, I dont really understand the wavlengths. My reds are maxzy's and my green is CNI.

    So the current specs are :
    100 MW 532 Green
    440 MW 660 Red
    ??? MW ??? Blue

    ...fill in the blanks

    EDIT:: Have the option of upping the Green to more power but would prefere not too

    Graham
    440@660 = ~130@635
    so
    440mw Red@660
    100mw Green
    and
    80mw blue!@473

    I would worry more about red being too weak then everything else.
    I hired an Italian guy to do my wires. Now they look like spaghetti!

  5. #5
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    And theres me thinking Ive got loads of red.

  6. #6
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    Heres a good balance that works on my small projector .....


    400mw of 660nm
    200mw of 473nm
    100mw of 532nm

    Basic rule of thumb...6 red 2 blue 1 green

    This will vary in using different wavelentghs. Do a search here...there was a lot of discussion of this some time ago.
    You are the only one that can make your dreams come true....and the only one that can stop them...A.M. Dietrich

  7. #7
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    Dr laser, could you explain how 440@660 = ~130@635 please. It's a really disaaponting value not that I think I finally understand what these numbers mean....

    This is my definition, tell me if it's right...

    Basically green 532 is the most visible lasing colour to the eye. The more you move above and below this number, the less visible the laser light will be.

    So a red which is closer to 532 is brighter than a red further from 532? Same for blue. Basic but is this true?

    Graham

  8. #8
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    Talking

    635nm will usually appear upwards of 5 times brighter than 660nm. But that comes at a cost of the beam not being as tight as the 660nm diodes...to a point. So a 100mw 635nm laser will look as bright as a 1/2 watt of 660nm in most cases. This can be a good thing.....if you can accept a little divergence that is larger than the 660nm . I understand it is a physics issue with the diode's emitters and collimation.
    You are the only one that can make your dreams come true....and the only one that can stop them...A.M. Dietrich

  9. #9
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    Cool Color balance revisited...

    Quote Originally Posted by laserLips View Post
    This is my definition, tell me if it's right...
    Basically green 532 is the most visible lasing colour to the eye. The more you move above and below this number, the less visible the laser light will be.
    So a red which is closer to 532 is brighter than a red further from 532? Same for blue. Basic but is this true?
    You are correct. The human eye does not respond linearly to different wavelengths. The peak for color sensitivity is between 550 and 555 nm, which is a green to yellow-green color. As you move away from green in either direction the eye's sensitivity falls off. However, it falls off faster towards the red end than it does for the blue end, which is why you need a lot more red than blue.

    But you still need more blue than green to achieve proper color balance. I don't know where Dr Laser is quoting his numbers from, but he's posted several times in the last couple weeks suggesting that you need more green than blue. That is BACKWARDS. The human eye is most sensitive to green, less sensitive to blue, and not very sensitive at all to red.

    Now, it is true that in complete darkness the eye's sensitivity peak shifts towards the blue end of the spectrum, and this may be where he's getting his numbers from. However, the sensitivity shift is is only applicable for a truly "dark-adapted" viewer. (This means you've been in near total darkness for many minutes; hardly the environment you'll find in a nightclub with other lighting effects, video screens, strobes, and the ambient house lighting.) So when figuring color balance for your projector, you can't use the dark-adapted sensitivity chart. If you do, you'll end up with way too much green and not enough blue.

    Here's an excellent article from the LaserFX.com site that explains color balance in great detail. Pay particular attention to this graph and the following paragraph:
    The photopically balanced "ideal" RGB power distribution resulting from this calculation reveals a surprising result: To look equally bright to the human eye, the red output must approach 60% of the total RGB power.
    To take full advantage of the laser's brightness and colour capability, a ratio of R=4.6 : G=1 : B=2.6 is required for the mixed gas power distribution. A laser with this ratio could be regarded as a photopically (visually) colour balanced white light laser. The laserist would then have the full power of the laser available to create bright, colour saturated images of any colour.

    So it's clear that you're going to need at least twice as much blue as green, and nearly 5 times as much red as green. Also, remember that the above numbers are based on a Kr/Ar laser, so the red is 647 nm and the blue is a mix of 488 nm and 456 nm. The numbers for a solid state projector are going to be slightly different, but so long as you are in the ball park you'll be fine.

    Here's another chart showing the peak in color vision. And here is a table from Sam's Laser Faq that lists the relative brightness for just about all the visible laser wavelengths you're likely to encounter. The table in the laser FAQ is particularly useful because it allows you to accurately calculate the color ratio no matter which wavelengths you are using.

    There's no need to be 100% accurate, since losses through your dichros will also change the balance slightly. Just be sure you're close and you'll be fine. Assuming you have analog modulation, you can tweak the balance after you get it all assembled.

    Finally, it's worth noting that some people design a projector with perfect color balance, and then increase the power of the green laser by several hundred mw when they actually purchase it. The reason is that they want the extra optical power for bright beamshows. When they want perfect color balance, they use the analog modulation ability to dial back the power on the green laser. But when they are looking for a big visual punch, it's nice to have a couple hundred extra mw of green. (Remembering that the eye is most sensitive to green, so a couple hundred mw makes a big difference.)

    Adam

  10. #10
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    Default

    I see, thanks for that excellent explanation.
    I've almost got the perfect ballance already with te red and green give or take a mw.

    The blue is gonna cost be a bomb though way more than I originally intended How the crap will I get a 250mw blue, I'd have to rob a bank

    Hmmm

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