How does laser color mixing work?

Hey there! I'm a video game developer and currently learning about lasers so I can replicate their behaviour in my game in the most realistic way with still maintaining fun in the gameplay.

Currently I'm researching the color mixing of lasers. I've read a bit on this forum about how it works - and I was intrigued. I've understood that mixing laser colors to form a odd-colored beam is only possible if the two "source beams" are completely overlapping each other (hence the usage of such X-cube).

In this example, a yellow beam is formed out of a green and a red beam:

(Taken from this forum, can't insert a link)

Is it true then that lasers behave completely the same way as digital / light color mixing works (additive color mixing)? So, a red, a green and a blue laser beam would result in a white laser beam? Or are there some special tricks with lasers?

Thanks!

mandelbrot said:

Hey there! I'm a video game developer and currently learning about lasers so I can replicate their behaviour in my game in the most realistic way with still maintaining fun in the gameplay.

Currently I'm researching the color mixing of lasers. I've read a bit on this forum about how it works - and I was intrigued. I've understood that mixing laser colors to form a odd-colored beam is only possible if the two "source beams" are completely overlapping each other (hence the usage of such X-cube).

In this example, a yellow beam is formed out of a green and a red beam:

(Taken from this forum, can't insert a link)

Is it true then that lasers behave completely the same way as digital / light color mixing works (additive color mixing)? So, a red, a green and a blue laser beam would result in a white laser beam? Or are there some special tricks with lasers?

Thanks!

Click to expand...

That's correct. Lasers, or any light sources or that matter, mix by addition. Typically, to make a white laser beam, a red beam (650 nm, typically), a green beam (usually 532 nm, sometimes 520 nm), and a blue beam (typically 450 nm) are combined with a dichroic cube into a white beam. Since the human eye is far less sensitive to red light than to blue, and less sensitive still to blue than to green, the power of each laser must be balanced for that in order to keep the combined beam from appearing blue-green.

Yup, they would behave similarly to pixels in the additive sense. Mixing is best if they overlap, be it by polarization or by allowing one range of wavelengths to pass and another to reflect. Not sure what your R&D budget is, but there are kits and guides for making your own RGB lasers, as well as pre-aligned modules. One of the better ones is here:

How realistic are you going? If you want to simulate apparent brightness as bostjan hinted at, you may want to look into CIE tables. Several tools have been made in the past to compare relative brightness, such as this one

Looking at color gamut charts, it's probably safest to give your starting wavelengths full saturation in a HSL scale.

If you aren't trying to get a lot of output power, these three color lasers can be had quite cheaply on eBay. Mine cost me ~$40.

bostjan said:

That's correct. Lasers, or any light sources or that matter, mix by addition. Typically, to make a white laser beam, a red beam (650 nm, typically), a green beam (usually 532 nm, sometimes 520 nm), and a blue beam (typically 450 nm) are combined with a dichroic cube into a white beam. Since the human eye is far less sensitive to red light than to blue, and less sensitive still to blue than to green, the power of each laser must be balanced for that in order to keep the combined beam from appearing blue-green.

Click to expand...

Thanks - interesting insights on the power of each beam to keep the balance. Not sure if I'm going to do it that realistically in the game - but good to keep in mind!

ZRaffleticket said:

Not sure what your R&D budget is, but there are kits and guides for making your own RGB lasers, as well as pre-aligned modules. One of the better ones is here:

Click to expand...

Cool - thanks! Not quite in my budget right now, but I'll see if I can find a cheaper kit somewhere to get me started!

ZRaffleticket said:

How realistic are you going?

Click to expand...

Probably not as realistic as matching the power output of each color, but the color mixing should be accurate.

Based on this input, I'm assuming that I could probably just use any linear additive color mixing algorithm available to mix the colors of my laser beams together.