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How to get perfect white?

borgqueenx

borgqueenx

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is this guide correct?
Lasers and Blanking

anything to add?

Im thinking of 300mw of green, 900mw of red(or should i search for 950 or 1000mw)
and then 600-700mw of blue?

Thanks :)
 





It depends on the red and it depends on the blue. If you have analog modules (and you should, anyway) then you can fine-tune the color with software.
 
It depends on the ambient light as well, white is a pretty relative thing.

If you are projecting the dark and the only real lightsource is the projection itself, getting the color balance off doesn't matter much as the viewers eyes will compensate for it... similar to watching tv with the color balance set wrong in a dark room.
 
The comparative beam wide/shape of the different lasers will also affect the "look" of the beam/spot. For example. usually the red beam is fatter than the green beam. This means that there will be some red light "outside" of the the green light

Remember, you are NOT actually making white light. You are shining three colors close enough together to "trick" the eye into seeing white light

Peace,
dave
 
daguin said:
The comparative beam wide/shape of the different lasers will also affect the "look" of the beam/spot. For example. usually the red beam is fatter than the green beam. This means that there will be some red light "outside" of the the green light

Remember, you are NOT actually making white light. You are shining three colors close enough together to "trick" the eye into seeing white light

Peace,
dave
Click to expand...

But that trickery to the eye wont help if it has 100mw of all rgb laser colors for example.
 
borgqueenx said:
But that trickery to the eye wont help if it has 100mw of all rgb laser colors for example.
Click to expand...


The point is that there is no such thing in projectors as a "perfect" white. The programs can give you the approximation for a balance of the colors. However, there are many other factors (including on-site variables, divergence, distance from projector, and simple alignment issues) that require adjustment.

Peace,
dave
 
but my estimations of power are good for basic projecting without being outside, in sun, clouds, rain, fog, whatever?
 
And it also depends what modules you choose for blue and red.

An example of this is;

500mw of 640nm red will appear about as bright as 800-1000mw of 655nm red. Similarly, a 445nm blue at 400mw would be less bright than a 100mw 488 argon.

Now obviously you dont want to go putting an argon in your projector for blue, thanks to the video projector diodes we can get plenty of blue, red is now the weak link. This is why 600mw of red 640nm with a nice beam profile sets you back $1500. Conversly 1.3 watts of 660nm red costs 1/3 this amount, but has a horribly big beam, and is much less visible.

I was told that 1:1:1 of 532nm green, 640nm red and 473nm blue is a good starting point. If your going with 660nm for red, and 445 for blue, the ratio is more like 1:2:4 So you would need 1.2 watts of 660, to match up with your 300mw green and roughly 500mw of 445nm.

(others please correct me if I am wrong!)

so for my setup I need 500mw green, 600mw 640, and around a watt of 445. I have to choose 600mw of 640 as thats the power level the laser comes in; next one below that is not strong enough. But I can dial back the red in software.

To start with for your setup though, go for 300 mw green, 600 mw of 445 and 1.2 watts of 660. (I'm assuming your using 660 as your red laser, and 445 as your blue). The red can always be dialed back if its too prominant, and the blue can always be dialed up if its too weak (assuming your using the video projector diodes we all love)

Remeber too that you are now getting into class IV power levels, so be very careful and wear your goggles when you start setting the system up.
 
Last edited:
daguin said:
The point is that there is no such thing in projectors as a "perfect" white. The programs can give you the approximation for a balance of the colors. However, there are many other factors (including on-site variables, divergence, distance from projector, and simple alignment issues) that require adjustment.

Peace,
dave
Click to expand...


This is the program Dave is talking about....It works well, Just not 100%.
Chroma - a laser color blender
 
vk2fro said:
And it also depends what modules you choose for blue and red.

An example of this is;

500mw of 640nm red will appear about as bright as 800-1000mw of 655nm red. Similarly, a 445nm blue at 400mw would be less bright than a 100mw 488 argon.

Now obviously you dont want to go putting an argon in your projector for blue, thanks to the video projector diodes we can get plenty of blue, red is now the weak link. This is why 600mw of red 640nm with a nice beam profile sets you back $1500. Conversly 1.3 watts of 660nm red costs 1/3 this amount, but has a horribly big beam, and is much less visible.

I was told that 1:1:1 of 532nm green, 640nm red and 473nm blue is a good starting point. If your going with 660nm for red, and 445 for blue, the ratio is more like 1:2:4 So you would need 1.2 watts of 660, to match up with your 300mw green and roughly 500mw of 445nm.

(others please correct me if I am wrong!)

so for my setup I need 500mw green, 600mw 640, and around a watt of 445. I have to choose 600mw of 640 as thats the power level the laser comes in; next one below that is not strong enough. But I can dial back the red in software.

To start with for your setup though, go for 300 mw green, 600 mw of 445 and 1.2 watts of 660. (I'm assuming your using 660 as your red laser, and 445 as your blue). The red can always be dialed back if its too prominant, and the blue can always be dialed up if its too weak (assuming your using the video projector diodes we all love)

Remeber too that you are now getting into class IV power levels, so be very careful and wear your goggles when you start setting the system up.
Click to expand...

Actually with 445nm blue you need LESS than green to get a good white balance. 500mW 655nm, 180mW 532nm and 160mW 445nm gives me a pretty awesome white. This is because even though 473 is more visible, 445nm stimulates the blue photoreceptor in our eye more, so you need less of it. This is also why 405nm is so effective at colour blending even though by itself it's almost invisible.
 
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Grix said:
Actually with 445nm blue you need LESS than green to get a good white balance. 500mW 655nm, 180mW 532nm and 160mW 445nm gives me a pretty awesome white. This is because even though 473 is more visible, 445nm stimulates the blue photoreceptor in our eye more, so you need less of it. This is also why 405nm is so effective at colour blending even though by itself it's almost invisible.
Click to expand...

This is why less 473nm would be needed to match an equivalent amount of 532nm, but why 473-only color blends came out looking like absolute crap.

445nm is not as bright, but is a 'bluer' blue than 473nm, by far. From what I've seen and heard, 445 to 532nm is in the ratio of 1:1. Although the equivalent brightness will be much lower, they will blend to form a nice cyan.

If you blend a visually equivalent amount of 445nm and 532nm, the 532nm will disappear completely. I've got pictures illustrating this in the Arctic review thread; check the effect out for yourself in person if you don't believe it. I was certainly surprised.

As a result, 445nm is often used in 1 to 1:1 ratios with 532nm (sometimes more, to compensate for blue lost off galvo mirrors).
 
Prototype pointed me towards Chroma in another thread (Thx mate) and I have had alot of fun playing with it. I was amazed at how a change in wavelength (405 vs 445 or 635 vs 658) can make such a huge change in visibility. I've never done any testing with Chroma results but I think it's output would get a person started in the right place. Deguin makes a great point about real world variables which software doesn't account for. Another one of those variables to consider is the efficiency of your optics.
 
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