I would pick red. Green is a bit easier for your eyes to see, but red is way, way easier for night vision systems to see.

Plus, as others have mentioned, red is more of an alert/danger color than green. People associate green with go, good, etc., and red with warning/danger.

A red laser is going to be tougher and harder to break than a green laser.

All consumer green lasers today are "DPSS" types, meaning they contain magical and delicate frequency-doubling optical crystals (blue does too, and yellow lasers even moreso). There's also an IR filter that is absolutely necessary for safety.

Red and violet consumer lasers are diodes, like LED flashlights, and more rugged. There are collimation optics to break, but no frequency-double crystal or an IR filter to knock loose.

Another minor issue is that there is more than one "red" laser. 658nm is the one manufacturers like to use because it's cheaper, but there is also a 635nm diode laser that is a slightly lighter red. The important point is that the human eye is 3x as sensitive to 635nm as 658nm: a 635nm red is easier to see: not as easy as green, but a lot cheaper and more rugged.

Any SAR is going to instantly recognize that a laser beam is not a flashlight, whether it hits them directly or they see the beam sweep across terrain. I doubt the color matters to SAR as long as it can be seen.

Doug has a write-up somewhere on actual experiments on using these to attract searchers. As I recall it takes a little effort to use it right: anyone buying a rescue laser needs to read that article.

You might want to read Doug's hands-on test of the Greatland Rescue Lasers:

http://www.equipped.org/rescuelaser.htm

The red laser was visible by the naked eye to 20 miles and with night vision goggles to 28 miles.

The green laser was visible by the naked eye well beyond 30 miles, and it was visible with night vision goggles.

OK folks, lets all just take a step back and look at the facts.

First: You don't have to worry about the fragility of a Green Laser Flare. It is standard issue for U.S. military, especially with various SF contingents in the sandbox. This is not your typical laser pointer

Second: The green is MUCH more noticeable than red. No pilot, or anyone else for that matter, is going to ignore a green laser being flashed at them.

Third: Red is NOT a universal distress signal color. Most strobes, including those USCG approved, are white, for example. The key is something abnormal that stands out from the surroundings.

Fourth: The Green is much easier to aim.

Fifth: I carry a Green Laser Flare for personal use.

For more info read: http://www.equipped.org/rescuelaser.htm

Regarding using the Green Laser on water. In our tests (USN), flying at 3000 ft, we could see the reflection of the green laser off the water surface at 34 miles distance using night vison goggles.

Even though the personnel on the boat didn't actually manage to hit our plane until we were 15 miles away, we could see the streaks of light emanating from the boat every time the beam intersected the water surface. Once we learned to look for that, it was very distinct even when the laser never actually hit us.

The biggest problem we encounted was aiming the laser. Some sort of sight would help. The two finger method isn't that great to aim it. Our plan is to couple it with a sight and luminous dial compass to help keep track of what part of the sky has been scanned.

Regards,

Tom A.

Tom,
Did the red laser have the same reflection off the water?

I believe I have posted this before-

I have tested my personal Greatland Rescue (red) Laser with the Maryland State Police Helicopter and it worked well. Having played with the green version at a NASAR convention, it is clearly superior to the red version. I just need to save up for a while.

Pete

I have both a red and green laser flare. The ONLY benefit the red one has over the green is it's size (slightly smaller).

Others have made the case that the green is a more effective signaling device, but it is almost impossible to explain how much better the green laser is until you use it!

As for durability, I have had one that has ridden in either my wildland fire kit or SAR radio harness every shift for the past three years (plus deployments, SAR events and training) and it is still going strong. I would put it in par with Surefire for quality and durability.

OH and on a side note, the green laser flare is visible through night vision even with the blue/green filters some aviation units use. These blue/green filters will block out (or make next to impossible to notice) some green led lights, which is why some SAR groups/agencies recommend red led lights vs green. When we tested the laser flare in green with NVG setup with the filter it was just as noticeable with the filter as without.

We didn't try the red laser. The green laser had such better performance from others testing it, we didn't really waste time with the red one.

JFCOM testing showed the green laser to be visible during daytime (except high noon) out to 5 miles. The red laser is largely ineffective during the day. That was another reason not to look closer to the red laser.

Tom A.

What do folks think of using a signal laser in urban settings, such as to potentially signal firefighters from your room during a hotel fire?