Brett asks (after seeing Act of Valor):
OK, just came from the show. A question for Nick… Why dual-use of red lasers and EOTechs on M4s in a lot of situations…is that par for the course? And with all of the sophisticated armament they dragged out, the SEALS would not have green lasers? Inquiring non-SEALS would like to know…
PS- The guns are great. The acting, notsomuch. But who cares…
I don’t know if SEALs actually use red lasers, but there would be a damned good reason for it if they did. And it has to do with SCIENCE!
Let’s suppose you’re in a dark room, and you need to point at something on the opposite wall. You have two laser pointers in front of you, one red and one green, both of equal power output (say 5 mW). If you point them at the wall, you’ll quickly notice that the green laser is MUCH easier to see than the red laser. The same thing happens with traffic lights at night.
The reason is that our eyes are much better at picking up green light than red light, especially at night. There’s some science-y reason behind it, but suffice it to say we humans can pick up green much better than red at night. It has something to do with the rods in our eyes being much less sensitive to those wavelengths that make up red light. On the other hand, our eyes are pretty much tuned to pick up on green light and see that very well even in the dark. So, going back to our laser pointer example, even if the two lasers are of equal intensity one will appear brighter to our eyes; the green one.
With this in mind, you might think to yourself “Eureka! If I use a green laser or dot, I’ll be able to see it better!” And you will! That’s why night vision scopes are green — they’re easier to see in the dark that way. But everything else besides the screen or the dot will be much harder to see.
The reason for the dots being red and the lasers being red is twofold.
First, red light has a tendency to not impact your night vision as much as other colors (which is why the military uses red filters on their flashlights at night), preserving it to be able to detect threats.
Second, red lasers have the ability to not be as detectable as a gigantic green dot flying around the room, a feature which would be very beneficial to stealth (again, military red filters). And despite not impacting your night vision as badly and not being as detectable to enemies, the red laser and sight will still be perfectly useful to those who are looking for it. It’s like having your cake and eating it too.
So, in summary, while I don’t know exactly what the SEALs are using these days it would make sense that they use red lasers and sights instead of green. It provides significant benefits in terms of stealth and night vision.