Lasers Obey the Laws of Physics

Isn’t it comforting to know that things work exactly how they should?

It’s awfully convenient that lasers come in red, green, and blue. This lets us make a bunch of other colors.
According to the laws of eyeballs, combining red and green light makes the light appear yellow. And that’s exactly what happens.

Yellow laser

I can’t believe it’s not butter!


It’s worth noting that just because the light looks yellow doesn’t mean it is yellow. The light is still composed entirely of red and green wavelengths, but due to how our eyes perceive light, it appears yellow. Cameras work the same way.

Here are some more predictably pigmented colors:

Aquamarine laserPurple laser

Combination of lasers

And when you combine all three colors, you get white.


Although it is strange that my 300mW red laser looks equally bright as my 5mW green one. Maybe physics is broken after all.