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Thread: RYGB or RYGCB projection software

  1. #1
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    Lightbulb RYGB or RYGCB projection software

    Are there any software packages that can intelligently handle more than just three (RGB) channels?

    I'd like of like to make a low power (well, hell, high power would be awesome but cost prohibitive) projector that includes more color channels... Kind of creating the ultimate color gamut.

    I mean, there is probably a diminishing return on investment, but wouldn't it be cool to have something like: 650, 638, 589, 532, 488, 450nm?

    I have seen a few commerical projectors adding a yellow channel but have no idea how they'd be controlled.

    Thoughts? Ideas? Dreams?

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    Violet is the only hue that is outside of rgb color space. It would be trivial to figure out how to isolate yellow (half way between red and green) and cyan (half way between green and blue). There is no way to make true violet in rgb color space. The best you can do is purple made by mixing half intensity red and blue. This is actually a dimmed magenta.
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  3. #3
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    For extended colorspace, the software would need to disable Red and green while outputting only yellow.

    Dynamics can do that. Pangolin does also support this.

    Dynamics calculates the output based on the output wavelength and input RGB color.
    Pangolin lets you select "key colors" where you can choose what pangolin should output. Other colors are than mixed/matched.


    I did build a projector with 660, 638, 532, 520, 465, 445.
    Mainly to get more power in a thin beam.
    If the software supports it and lets you control each color separately, The colorspace is awesome.
    Yellows are much less "white" by mixing 636+532 rather than the now common 520+638.
    Magenta does really punch with 660+445. But 465nm looks way more nice if a "just blue" is needed.

    I also experimented with a single mode projector with:
    660nm, 638nm, 571nm, 520nm, 488nm, 445nm

    That a very good mix. The yellow would be even better if the wavelength was a little higher (571->590nm).
    However cyan is just awesome. The color is way more saturated if 488nm is used.
    I was quite sad that most of the software can only do 6 colors. For best experience, I would use:
    660nm (or even higher, there are 675nm 1W diodes- extends the colorspace quite a bit)
    638nm (to have the option of better visibility- anything longer than 642 does take a hit at apparent brightness)
    589nm (expensive but nice to have for good yellow and more white power overall)
    532nm (to extend colorspace in the green-yellow direction)
    520nm (to extend the colorspace in the green-blue direction)
    505nm (would be nice to extend the colorspace, sadly, there are only low power diodes)
    488nm (a must have for nice cyans)
    465nm (also a must have for bright blues- mixing green 488 and 445 does not get you the "pure blue" in saturated)
    445nm (brighter than 405 for bridging the gap between 465 and 405)
    405nm (needed for good magenta but too dim to extend the 465 to a lower colorspace)

    That would make this:
    Click image for larger version. 

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    Quite a nice colorspace compared to AdobeRGB.
    White is also better because its not so "monochromatic".

    The effects of the bigger colorspace are also easy to see in a color chart.
    Pure wavelengths are located on the edges, giving you the most saturated color thats possible.
    A mixture of 3 colors can not touch the edges and is therefore biased to the mid point which is white.

  4. #4
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    Thumbs up Wow - What a Reply 😎

    What an amazing post in a thread. With laser focus 😉 you hit on exactly what I've been so facinatwd with.
    Wish I could see those projectors you made.

    A couple questions:

    1) when you say Pangolin supports this, I assune Beyond and not QuickShow. (Feel silly even asking!)

    2) any experience combining different diode colors (650 & 638) with a pbs to expand the color space? I assume this isn't difficult though it would be best to compenstate for the rise/ fall times using something like the boards Stanwax sells? (I'd need to buy two boards since the stanwax only support 3 color channels)

    Thanks for that extensive and thoughtful post.

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    QM2000 supports this, FB4 supports this, don't know about FB3 but I think it does. 6 Color control output lines are available. I'm not sure how Quickshow handles it, but Beyond certainly gives you full control without sacrificing other wavelengths.

    Pro tip: Add 5-6% green to your reds or darker red just by default. Usually done in analog with an op-amp, actually quite easy to build a summing amplifier to drive the green input line with a little bit of the red signal. With some older drivers you could just use summing resistors on the inputs. Effectively shifts a 647 or 650 nm red to a 640, or a 638 red to roughly 628 when mixed by the eye. Adds "punch" to your red. Its a trick invented by the laser video projection guys (Doug Dulmalge) when they did not have short wavelength reds.

    Dang it, now I'm going to have to modify my solid state projector with a "boost red" switch this weekend. Hadn't thought about that when I built it.
    I can do it in Beyond, but what fun is that.

    On an Ion Laser with a PCAOM for control, we had an amazing color gamut.

    Steve
    Last edited by mixedgas; 04-28-2022 at 07:25.
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  6. #6
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    Default Ions, Color Gamut, and PCAOM

    Quote Originally Posted by mixedgas View Post
    QM2000 supports this, FB4 supports this, don't know about FB3 but I think it does. 6 Color control output lines are available. I'm not sure how Quickshow handles it, but Beyond certainly gives you full control without sacrificing other wavelengths.

    Pro tip: Add 5-6% green to your reds or darker red just by default. Usually done in analog with an op-amp, actually quite easy to build a summing amplifier to drive the green input line with a little bit of the red signal. With some older drivers you could just use summing resistors on the inputs. Effectively shifts a 647 or 650 nm red to a 640, or a 638 red to roughly 628 when mixed by the eye. Adds "punch" to your red. Its a trick invented by the laser video projection guys (Doug Dulmalge) when they did not have short wavelength reds.

    Dang it, now I'm going to have to modify my solid state projector with a "boost red" switch this weekend. Hadn't thought about that when I built it.
    I can do it in Beyond, but what fun is that.

    On an Ion Laser with a PCAOM for control, we had an amazing color gamut.

    Steve

    If only three phase power were more accessible and portable... 😉

    Guess you could combine diodes and use a PCAOM to modulate them though...

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    Single phase can get you 2 watts of whitelight. However it an artform to achieve it.

    Steve
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    Quote Originally Posted by mixedgas View Post
    Single phase can get you 2 watts of whitelight. However it an artform to achieve it.

    Steve
    And save on your heating bill too! 🤪

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    Quote Originally Posted by mixedgas View Post
    Pro tip: Add 5-6% green to your reds or darker red just by default
    I dont like this idea. You get just around 5% of off your green power in added brightness but you loose quite a bit saturation and "deep red" look.
    It would not be much brighter as your eye just responds in the same way to the red component.
    Deep red triggers the red receptors less, therefore the overall excitement level of the receptors is just not as high as on real 638nm red.

    Quote Originally Posted by [COLOR=#3E3E3E
    MountainGoat[/COLOR]]
    1) I assune Beyond and not QuickShow..
    I think its just Beyond. I did not check in quick show.

    Quote Originally Posted by [COLOR=#3E3E3E
    MountainGoat[/COLOR]]
    2) .. combining different diode colors (650 & 638) with a pbs ..
    2.1) .. compenstate for the rise/ fall times
    For 2. I would use dichroic!
    PBS work grate as they dont care for wavelength. However they deny you the possibility to use 50:50 polarisation modules e.g. less power.
    With dichroics you can just PBS 2 diodes of the same color and than mix them together with the said dichroic.
    I used a PBS to mix my 575nm module into the RRGBB mix that was done by dichorics. I did that because i could not find a 575nm dichroic and i only used one diode of each color for my test.

    In my RRGGBB high power projector i use a mixture:
    A 660nm/638nm dichroic to mix a 16 diode 660nm PBS+knive edge array with my 6 diode PBS+knive edge 638nm array.
    That seems excessive but its actually a quit good match. Around 3,5W 660nm red to around 1W 638nm red.
    Green is done by combining a 1W cni dpss and one 520nm 1W cylindrical lens corrected diode together with a PBS.
    Blue uses one 465nm and a 445nm diode also with cylindrical lenses and a PBS. I could have used a 465/445nm dichroic but i didnt need the power.

    I purchased my modules from Live lasersystems, they also have the special dichroics.

    2.1) just use the same drivers on all your diodes. My goto is also from Live Lasersystems. They offer drivers that have adjustable threshold current and threshold voltage.
    I dont know about other drivers that offer this level of adjustability. The threshold voltage comes in handy to adjust every channel to start lasing at the same point.
    They are also quite fast, i think just above 1Mhz modulation frequency. So no need for any signal boards.

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    Regarding the need to synchronize the rise and fall times of different diodes, while it's true that using a high quality driver helps, if you want the timing to be absolutely perfect, you could always install a DZ color board. This board allows you to set a separate delay on the rising and falling edge of the modulation signal for each of the three primary colors (R, G, B). (If you are using a 6-color system, you just need a second board for the other 3 colors.)

    Granted, most direct-injection diodes have markedly-similar performance these days, so as long as you are using the same driver for each color you are probably fine. These boards were originally designed for projectors that were using DPSS lasers for both blue and green, with only the reds being direct-injection diodes. Despite the notoriously lousy modulation performance of your typical DPSS laser from 15 + years ago, installing one of these boards would give you amazingly accurate color modulation across all colors. I couldn't believe the difference it made on my first RGB projector (which had 660 nm red, 532 nm green, and 473 nm blue).

    But if you're noticing any slight differences in modulation response even with an all-direct-injection diode build today, a DZ color board will certainly fix this.

    (Note that DZ stopped selling these boards many years ago, but he passed the circuit design on to Stanwax, who still sells them on his site.)

    Adam

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