What is the correct fomula for ~ "Red to Green to Blue" ratio

[Weiland]

THe formula is arround 1-1-4 (G-B-R) for 655nm red, and 1-1-2 for 640nm red.

Some say 1-2-4, but then I find the beam too blue, but it all depends on your optics.

You hit it on the NAIL , That's the figure i was looking for.

Thanks again for the help guys.

Weiland

[gottaluvlasers]

"theoretical" White balance:

635= 42.4%
532= 25.1%
473= 32.4%

Example- 1W RGB=

635= 424mW
532= 251mW
473= 324mW
-------------------------------------

650= 70.3%
532= 13.1%
473= 16.4%

Example- 1W RGB=

650= 703mW
532= 131mW
473= 164mW

But as i will always say," white balance" is a highly overrated and highly argued topic. What you see as White, i may see as reddish. What you see as greenish, i may see as White.

build as much power into your system as possible. No client, no customer, no audience member will ever see a laser show and say, "Hmmm....that kinda sucked. The lasers white seemed a little too Green to me!" LOL. But i GUARANTEE you, an audience member, or a client will tear you a new a**hole if you do a show and your laser isnt visible enough!!

Some of the best lookiong "white balances" i have ever seen were on "off the charts" beyond comprehension laser power mixtures.

What looks good on paper and in neat little computer programs, holds little to no value in the "real world." (Waiting for the flames now!!! )

RELAX everyone!!! its just an opinion!!! its not a comandment!! in my 5 years of laser shows, i have never once had a customer, clinet or audience member complain or "bad mouth" a single show of mine because of mismatched colors!

And i have mixed some WEIRD ASS lasers!!! LOL...3.5W/532 with 500mW 635. BEAUTIFUL!!!!
4W/532 with 200mW 473....AWESOME! 1W/532, 500mW/635 200mW/473. of course, dont be silly, the green overpowers, but the blue is still there and its still visible. clients love it. customers love it. audience loves it.

Who else are we doing shows for?? Show up at an ILDA awards show or a PL SELEM meet...yeah, there youll have some problems. HOWEVER.......those shows don''t pay the bills!!

*my* opionon-

get as much power as you can for your budget!

-Marc

[ElektroFreak]

^Absolutely true.

[buffo]

First off I would like to say Hello to everyone here

Hello Weiland - Welcome to PhotonLexicon.

I think we may have spoken on the phone before, around August or so last summer... Were you the one who contacted Patrick Murphy (ILDA president), and he gave you my number? I'm Adam Burns, and I'm in Charleston, SC. If you're the guy I'm thinking of, we talked about SELEM, but since it was only a week away at the time, you were unsure if you'd be able to make it.

Regardless, you've come to the right place to feed your laser addiction. As for the color balance issue, there are a number of variables that you need to consider. Chief among them is the wavelength of red that you use. The shorter wavelength red you use, the less red you need to make white. This is because the human eye isn't very sensitive to deep (long wavelength) reds.

As an example, my projector puts out 375 mw of red (at 660 nm - a deep red) when it's making a perfectly-balanced white. But that is mixed with ~95 mw of blue (at 473 nm) and just 60 mw of green (at 532 nm). (These are output powers measured at the aperture, after losses from the internal optics.)

If I were to use 635 nm red in my projector (while keeping the green and blue the same), I would only need between 75 mw and 100 mw of red to achive the same white! So the wavelength you choose makes a big difference on the color balance ratio.

Note that some red wavelengths have better beam characteristics than others, so that may also influence your decision. And we haven't even talked about changing the blue wavelength yet. (Yeah, that changes the numbers too!)

As a *general* rule, you can assume that 1X green to 1.5X blue to 3X red will get you in the ballpark. But the best course of action is to use Tocket's excellent "Chroma" software to run the numbers yourself. That way you can input the exact wavelengths and power levels you'll be using and see where your color balance ends up.

And, of course, as long as your lasers and controller all support analog modulation, you can adjust your color balance after everything is assembled to get it perfect.

At this point I have to stop and acknowledge Gottaluvlasers' post above: We all tend to obsess over the "perfect" white, but this is *not* necessary. You can have a beautiful show even if your color balance is completely out to lunch. There are a lot of mixtures that look good, even if they don't add up to a perfect white. So don't lose too much sleep over it. Get close when you purchase your lasers, and if you don't like the resulting white, just tweak your color balance in software a bit.

This is also the reason why a lot of people put a larger green laser in their projector than would otherwise be necessary. Having that extra power to make your beams brighter really helps, and being slightly green-heavy really doesn't look that bad. (In the interest of full disclosure, I should point out that although my projector only needs about 60 mw of green to get a perfect white, I have a 150 mw green laser installed!) Since green is (relatively) cheap, it makes sense to add a little extra.

I hope to meet some of you in the future at the next "SELEM" event.

Unfortunately, SELEM is an annual event only, which means you'll need to wait until August for the next one. But we do hold smaller events from time to time. We're thinking about holding one in Florida (FLEM) around the end of February. We normally hold the Florida meets in Tavares, which is about an hour north and a bit west of Orlando. (Figure a 6 to 7 hour drive one way for you, depending on how fast you drive.) Keep a watch in the meet and greet sub-forum for details on that meet.

Also, there are several PL members in North Carolina, and we've often talked about holding a LEM in either North or South Carolina... If we can get some enthusiasm built up, I have a few ideas for venue's that might work. We'll see I guess.

Adam

[ElektroFreak]

^An excellent answer.

To the OP: You'll find that color balance is very important if you're trying to match two or more projectors to be used together on one stage. It's all too easy for projectors to be of the same design, but have slightly different color balances. Adjusting to to match makes the whole show better. If the difference is big enough from one projector to the next it can be extremely noticeable and annoying if you're a laserist.

[mccarrot]

As a *general* rule, you can assume that 1X green to 1.5X blue to 3X red will get you in the ballpark.

Uhm, I think you will have a little bit too less red.

Let take your own projector putting out 60mW of red, according to above quote you need to balance this with 180mW red. this is way too little red.

I would more say 1:1:4 or even 1:1:5 to balance.

Why not 1,5x blue, just becouse blue is damn expensive and it better for you funds to have more green than blue.

[buffo]

Uhm, I think you will have a little bit too less red.

I said as a general rule. The 3X red assumes he's going to use 650 nm or 642 nm red. You are correct that if he selects 660 nm red he will need much more. Also, if he decides to use 635 nm red, he'll only need between 1.5 and 2X red. As I said in my post, there are lots of variables, which is why it's best to use the Chroma software.

As for the red selection - these days it makes more sense to use 642nm (if you can afford it) or at least 650 nm, but back when I put my projector together the only real choices were 635 nm (fat, ugly beam, but bright) or 660 nm (beautiful, tight beam, but hard to see). Most people building a projector today would consider 660 nm red to be close to a last resort, right before 635 nm red.

But 650 nm red offers a beam that is almost as good as 660 nm red, while 642 nm red offers equal (or better) beam quality *and* greater perceived brightness. (But at $100 per diode, they're more expensive.) And since both 650 nm red and 642 nm red are much more visible to the human eye, the 3X rule is close enough to get you in the ballpark. If you want to be 100% accurate, again - fire up Chroma.

Why not 1,5x blue, just becouse blue is damn expensive and it better for you funds to have more green than blue.

The 1.5X blue will get you closer to an ideal color balance. It may be cheaper to have more green than blue, but it's not better for the color balance or your modulation response. Still, most people (including me) throw that number out the window anyway. I posted it as a guideline, remember.

For example, my RGB projector initially had a 70 mw green, a 100 mw blue (473) and a 425 mw red (660). After optical losses, for a balanced white output I had 55 mw of green at the aperture, 95 mw of blue at the aperture, and 350 mw of red at the aperture. This made a very nice white, and the output numbers were close to 1X green to 1.5X blue. (But over 6X for red, because of the long wavelength red diodes I used.) All the lasers were operating very close to their full power settings. (The red and green were adjusted down ever so slightly.)

Then I replaced the green laser, because it had modulation instability problems. When I was shopping for the new one, I decided to purchase a 150 mw green, even though I knew I didn't need the extra power. So now everything else in my projector is still the same, except that I have more green. And you know what? I almost never use that extra power, because I'm always running my projector using the "color blanced" palette.

Sure, I could switch to the "high power" palette and get a little more punch, but I prefer the look of a balanced palette. So I basically wasted that extra money on the 150 mw green, right? But was that such a bad decision? Not really - because the difference in price was just $50!

Bottom line: you base your laser purchases on how much blue you can afford, because the blue laser is going to cost you more than the red and green combined. Then you buy enough red to color balance the blue. And finally, you buy your green laser. You really don't need much green, but green is so cheap (compared to red or blue at least) that most people get a little extra just to have some surplus power. So what if the laser spends most of it's life running at a reduced power setting?

One final concern: Don't go overboard if you decide to buy extra green power. I once installed a 275 mw green in my projector as a temporary fix. This SUCKED. The green was running so low that the modulation response suffered. It would come on too bright and then dim back down to the proper level. It totally screwed up my colors, and I was not happy at all. So if you do add extra green, don't exceed the power of your blue laser by more than 50% or so. If you do, you may suffer the same problems I did.

Adam

[mccarrot]

One final concern: Don't go overboard if you decide to buy extra green power. I once installed a 275 mw green in my projector as a temporary fix. This SUCKED. The green was running so low that the modulation response suffered. It would come on too bright and then dim back down to the proper level. It totally screwed up my colors, and I was not happy at all. So if you do add extra green, don't exceed the power of your blue laser by more than 50% or so. If you do, you may suffer the same problems I did.

Adam

Correct!, in one of my RGB's I have 250mW green 100mW blue and 400mW red (660nm).

I have to dail down the green to 55% to get it nice balanced, but at half power jellybeaning/grinding is way more visible than at full power.

ps. I have too little red in my setup, so I'm pllanning on building a 600/800mw 660nm quad setup.

[buffo]

I'm planning on building a 600/800mw 660nm quad setup.

Sounds cool! Be sure to take lots of pictures!

Adam