Comparing Green & Red Laser Technology

I noticed several weeks ago at the gun store were I work that the green laser was much brighter then the red. I brought this to the attention of the owner and we compared the two. Again the green much brighter.

Green layzer

Dr. William Thornton, of Westinghouse, found in the early 70’s that the human eye can best discern colors at 450, 540 and 610 nm (the primary colors). Of these, the dominant is green (540 nm). This is why the best output color for night-vision systems is green, usually 555 nm.

As a vision scientist, I can tell you that night vision (rod vision) has peak sensitivity at about 540 nm (green light). This means that under dark condition your eye will be most sensitive to this wavelength because in the dark your eye uses rod photoreceptors for all vision.

However, I will also tell you that exposing your dark adapted eye to light of this wavelength (green) will seriously reduce your night vision in those photoreceptors of the retina that are exposed (or see) this light. Sure, we are dealing with a dot, but I am not so sure I want to potentially handicapping my night vision by flashing an intense green light around.

A red laser 640 nm, on the other hand will never ever cause this effect. You will never lose any night vision capability with a red light because the rods photoreceptors do not detect this wavelength.

Yet, under really dark condition, shining this green laser in the eyes of an opponent would represent a tactical advantage for me because it would absolutely stun my opponent’s night vision for a short time. Unfortunately for me, as long as the green laser is on, he could easily see exactly where to aim to shoot me.

ls the green laser really better after all? Maybe for daylight only. I guess I had better buy both flavors and exchange them on my gun at sunset.