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.

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45 Responses to Ask Foghorn: Why Red Dots and Red Lasers and Not Green?

  1. The current generation of green lasers are also more sensitive to extreme temperatures, making them less reliable under field and in maritime conditions.

  2. Quick note on the night vision thing:

    Night vision is artificially colored green because the human eye can distinguish between different shades of green better than other colors, not because it’s easier to detect. This is especially beneficial if you’re trying to navigate with just a greyscale picture in front of your eyes.

      • Colorblindness would be a disqualifying factor in joining the SEALS. I’m not sure, but I thought it disqualified military service, but I can’t remember if it was that or just certain jobs.

        I guess that explains why RF was not a SEAL. 🙂

        • I know someone who qualified as a jumpmaster back when they used to jump both doors of a C-130 by waiting for the guy on the other door to tell his stick to go.

      • Wikipedia suggests 7-10%, with citations to sources (which I clicked through to) which appear reasonably likely to be authoritative.

  3. Some would say that a well-equipped SOF person on a mission requiring a laser pointing sight would like a color that matched their red-dot or holographic sight, one which showed up similarly in their NV device. Others would say that actually high-quality high-power infrared lasers are the name of the game these days, since most targets will not be able to see them and they show well with good NV equipment. I don’t know of a better or more popular model than the Surefire L75. These IR lasers work both as sights and as marking devices, and have a range in good weather of 3-5 miles.

    • Yeah, infrared seems like it would be the way to go for stealth. Coupling visible light (red) lasers with NV equipment doesn’t make much sense to me. I’m pretty sure that the real “operators” don’t run around with their lasers turned on the entire mision either. I commented to my buddy after seeing the film that the red lasers were probably used for the viewers sake.

  4. As someone who works with LASERs a lot, it’s an issue of the diode. The stimulation of light that makes the LASER beam is a specific quality of the diode (the crystal that gives off the light). Red solid state diodes are common. Diodes that produce green are expensive, delicate, and use a lot more energy.

  5. As Big J says, red lasers have been (still are) cheaper to produce.
    Once green lasers become cost/quality competitive with red, they’ll be everywhere.

  6. Before I retired I was familiar with and used both the IZLID (visible with NVGs only) and the Green Beam Designator, aka the GBD-III (visible to the naked eye) from B.E. Meyers.

    Sorry – DoD buyers only.

  7. There are quite a few other problems with green and other high-frequency lasers. While easier to see than red lasers, green lasers often produce a visible beam due to elastic (aka Rayleigh) scattering of water and air molecules at these wavelengths. Remembering from high school physics, the higher the frequency (towards violet) the more energy a particular light wave has. Since the amount of scattering is proportional with energy, the effects are amplified the more you go towards violet light (and thus away from red).

    Most green lasers (and higher frequency lasers in general) are actually red lasers that have their energies and frequencies “double-pumped”. IIRC, higher-end red lasers (such as SureFire) also use the DPSS technology to give a better quality beam with less aberrations. This makes them expensive, but very “crisp”.

  8. It looks like the science has changed regarding red being best for dark adapted vision. Because the eye is less sensitive to red, red light must be significantly more intense than otherwise necessary. With red, either detail is not observable or dark adapted vision is actually being impaired by light that is so bright it is working against dark adaptation regardless of the color red.
    Because green or cyan light can be used at much lower intensity, dark adaptation is less impaired.
    Examples (cockpit and loading bay illumination w cyan):

    • Part of the reason red is used in the military is exactly that reason. You cannot see it at distance. Cyan is used for when you do want it seen at distance, like landing lights. The issue they talk about is people using a bright red light. That is why the military uses red lights that are so faint that your eyes must adjust to them. Anyone with a Cutterman’s pin can tell you that when you set Condition DZ (turn off all white lights, seal off all windows and turn on the red lights) it takes a couple minutes for your eyes to adjust. At first it seems completely dark, slowly your eyes adjust to the very faint red light and you can start to see. The ship however disapears into the darkness of the night since any red light escaping does not transfer long range.

  9. As a guy who works with Night Vision Goggles and laser aiming devices for a living, I will weigh in.

    Red lasers are cheap inexpensive; green lasers are more costly and have much longer range with the unaided eye. Green lasers are, for the most part, invisible to NVGs while red lasers even though they have a short range reflect off of the dust and moisture in the air enough that while using NVGs the operator can see the entire beam, not just the spot it is focused upon.

    Red filtered flashlights and environment lighting WERE the color of choice for military ops before the advent of NVG technology. Red light is the light that our eyes are least sensitive to and the least prevalent light at night so night vision is mostly retained after being exposed to red light. A fairly bright flashlight with a red filter APPEARS less bright than the same flashlight with a blue/green filter even when they actually put out the same amount of lumens (measure of luminance).

    Blue/green lighting is now the norm for cockpit lighting for armored vehicles and aircraft where NVGs are used. Since our eyes see blue/green very well, we can drop the voltage to the light to 1/4 the voltage of a red light and still be able to read well. The NVGs don’t care about the actual color so the 1/4 lumens has a much less interfering effect even before the next concept is applied. NVGs used in air and ground vehicles have a filter built in which eliminates the interference of blue/green lighting of less then 525 nanometer wavelength. NVGs used by soldiers (and Seals) who don’t spend a great deal of time in vehicles have the filtering removed.

    NVGs are also capable of viewing infrared light. So, most military laser aiming devices are also, with the flip of a switch, IR capable and thus only visible through the NVGs. So NVGs see IR, R, O, Y, G (Start to filter here). B, I, V and UV are invisible.

  10. Red lighting has another problem. Red light being very short wavelength acerbates near vision because it naturally tends to fall short of the retina wall.

  11. One of the drawbacks of green lasers is that it is easy to see the beam at night. It’s one of the main reasons that we use them as astronomy pointers and that the Air Force uses them in survival kits for marking downed airmen positions. As a result, one should remember the old dictum about tracers; “Tracers work BOTH ways.” If you don’t want them to know where YOU are, mite not want to use a green laser…..

      • We put cheap red lasers in Army aviation survival vests for the just he opposite reason. The green is visible to almost anyone. The red laser is visible only to people very close OR to people wearing NVGs. An IR laser would have been preferable but I could put 200 red lasers in all of my crewmember’s vests for the price of a single IR laser. And the cheap red laser of choice was a very small key chain type.

  12. Im pretty sure the laser usage in that movie was for Hollywood effect. Just like the silenced M-14 being airgun quiet. Still, the movie was excellent.

    Green lasers are typically more fragile then solid state red lasers. The DPSS setup is at risk for being knocked out of alignment.

  13. Lots of cool and interesting stuff I’m learning here. Who’d of thunk I could gets me an edumacation on the intrewebs?

  14. Subjectively, in daylight I can see the dot of green laser much better than the red. The red gets washed out, while the green is still fairly vivid. I don’t know if that’s just me or if there’s some science behind it.

    • My next self leveling builders laser will be green. Assuming I don’t go completely blind before the economy turns around…

  15. Green lasers in common use are very high powered IR lasers that are run through some optical tricks to produce green. They are power sucking and don’t work when it is cold. I think the new Surefire green lasers are actually green lasers, without the IR to optical conversion.

  16. Hahaha, how idiotic.

    Meanwhile, Crimson Trace and Surefire rush towards the green light and LEOs would rather have the green lights.

  17. The SEALS probabally have AN/PEQ 16s mounted on their rifles. Or maybe AN/PEQ 15s, as they seem to be well liked.

    They mount a visable red laser, an IR laser, and in the case of the AN/PEQ 16, they also mount a visable white and a IR light.

    No one uses visable lasers in military settings. Because, really, they dont offer very much of anything over a good high quality red dot or reflex sight…Especially considering that firefights take place at much longer ranges than civilian defensive engagements. IR lasers are very commonly used, though. You can see them for a very, very long way at night, and for some one wearing NVGs, its very difficult to get a sight picture through most optics. So they’ll run IR lasers at night.

  18. Intermittent, selective and judicious use is the key with all of them. Or you won’t need to worry about the colors anymore.

  19. I understand that red light does not affect your vision as much as green does, but is a green laser really going to have any kind of significant effect on night vision?

  20. There is also the electrical and mechanical properties of the lasers. Current green lasers operate in temperatures between -10 and +50 C. That seems like a pretty wide range but performance and battery life fall off pretty drastically as you vary from ~20-30 C. Battery life is short on the green lasers, they are power hogs.

    Red semi-conductor lasers are generally much cheaper, mechanically simpler, smaller, lighter and get much better battery life.

  21. I suspect that some left the infra off of Infrared here.

    The military, at least the Army part, makes extensive use of Infrared lasers. They can not be seen with the naked eye but can be seen with nigh vision equipment. If you put the cap on the end of your NVG you can even use the IR laser in daylight, provided your lens cap has that little hole in the center.

    The Army does use green lasers. As spot lights. Mostly as a way of getting the attention of civilians on the battle field. Thus if you are driving along in some third world country (or Detroit) and your windshield all of a suden glows green, stop your car as fast as you can. This will prevent the sudden loss of bodily fluids.

    Of course Power Point Rangers use the visible red lasers almost exclusively. They are less likely to have backscatter and impair the vision of your CG.

  22. I read somewhere that green lasers can have a visible “beam” in low light situations. Because of that they were popular for some people to use when instructing others on star gazing. In a combat situation, having a glowing line that points to you is not a good idea.

  23. Everyone is missing the point. Use the right tool for the job. Obv, the Seals have multiple weapons at their disposal. The normal folk do not have 6, M4’s all with different zero’d optics for the right mission. Plus the Seals are a team. For outdoor day, they could use green, night or indoor, Red or IR. No true hit would be used with a laser. It would be with a scope or optic. The prep and scenereos are endless I’m sure and always go through rigorous testing. Lasers are only for quick aquisition assault. If you have one weapon make sure you can see it and it works for you.
    When I went on an Air Assault mission, we pilots would sign out a M4 with iron sights b4 the mission. We never had an assigned weapon and it definitely wasn’t individually zero’d. We most definitely never had optics or lasers because we had to turn them back in. It is too rough in the Helicopter, there’s no mounting it in the ACFT, it Goes right on the floor.
    My dad is retired old school SF and I can’t convince him at all optics or lasers are better than iron sights. Too much room for error and weight he says. What happens if they break?
    Ok, old school and new school and the Call of duty junkies. IMO don’t even think about a laser or Optic until you are an expert with iron sights. Also, if your not going to get the best, your zero will not hold. Ie, your If your wife was held at gun point and you needed a laser head shot please think about if you bought it on Amazon.? Also, indoor, Green hurts my eyes bu,t outdoor you can shoot Long range.
    Get off your benches and tripods and exercise with your weapons. Practice holding it up so you don’t get muscle failure. This is what we did in Basic.

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  25. This may be a comment off the beaten path but here goes…. I’ve been searching for a scope (3-9 power) with an illuminated dot (red or green). Honestly the green simply looks cool. I do know however, that as a mariner (recreational), ships are all equipped with red lights in the cockpit for use at night as it is the light frequency that least affects night vision with the naked eye. So it seems to me that an outbound light flow for night use is probably best as red. I would be interested to hear opinions on the preferred reticle color for a scope for general purpose use (no night vision in use). Very layman’s curiosity, but I really enjoyed all the thought provoking comments!

  26. David….try the Leupold Firedot variable scopes with the red dot (30mm tube). They also offer a 1″ tube with a green dot. Myself, I found the green dot getting lost in green vegetation background. The red, not so.

  27. I am an Ex Green Beret. I have a Green and a Red Laser Device. I gave the Green to my son because I can’t see the Green as well as the Red in the Dark or Daytime. I would like to comment on the “Red/Green “Color blindness., which I Am .
    Being a Legally armed Citizen . Just find a place to test either or both and go Make an Informed  Decision. . Thanks for all the great info.             

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