If the aircraft personnel can see the green light, how would they know if it's powerful enough to do them damage?

The FAA only investigates incidents with aircraft. Who has the time to investigate the idiots at the side of a busy freeway aiming at motorists? Pets? Your kids?

Sue

They don't know, which is why the press reports it. If they remembered their high-school geometry it might not be newsworthy.

Nearly all such incidents are with DPSS green lasers since they're cheap and easy to find, and the beam is easy to see. Due to the way they're made 400mW is about the maximum output power. That's at the exit: about 1 mm2. By the time the beam hits an aircraft in flight and the beam has diverged to several inches or more the power will be at least a couple of orders of magnitude below the damage threshold.

(a nut willing to power a bench laser from a car battery is another thing altogether - I'm talking about what guys use when they buy a common handheld laser with internal batteries)

Don't get me wrong: it's not a good trick. It can easily be to a pilot like someone climbed up to the window and flashed a bright flashlight, forcing a go-around to get night-vision back. A medical helicopter landing in a tricky environment could be in serious trouble.

Fortunately goggles than block 532nm are cheap and don't otherwise hinder vision: if it really becomes a problem for pilots there's a quick & cheap solution available.


The Sheriff, who already investigates attacks on freeways. Nothing new here.

I look at it as I look at the problem of kids dropping bowling balls off of overpasses into freeway traffic. Dangerous, etc, but banning bowling balls isn't the first thing that comes to mind.

The funky military canopy is for dealing with attacks by other than DPSS lasers. That, and any Chinese efforts at developing laser "dazzlers" is likely a deadend as the era of human eyeball involvement in air combat operations is already coming to an end.

Getting back to the topic at hand: no one else has addressed this point. I'm not an expert in the rescue aspect but I would say that the Answer is NO, the DealExtreme is not substitute for a Greatlands laser and is not useful as a rescue laser.

I do not think any laser whose beam is a spot can be used because there is no hope of hitting the aircraft looking for you. Unless the aircraft actually intersects the laser beam a few inches or feet in diameter they won't see a thing.

The Atlas Nova laser I linked to earlier has several different nose pieces to get different beam shapes, most of which would be useful. I think Nova Lasers sells optics that can do this too. I think they might work, but might not be a better buy.

No flashlight will come close to a laser. There are two problems:

1. At 532nm green DPSS lasers are essentially at the frequency to which the human eye is most is most sensitive, and all of the output power is (hopefully!) at that best-case frequency to be seen by a rescuer. A flash light spreads its power over a wide range frequencies with not much at any particular frequency and wastes much power on frequencies the human eye isn't very sensitive to.

2. The beam of a laser is usually very tightly focused and diverges slowly with distance. Even a mile away the beam is tight enough that the power illuminates a small area. By contrast a flashlight beam expands rapidly, even with a "tight focus" reflector: the beam is much larger at 50 feet than at 10 feet.

The total output power of a flashlight might be an impressively large number but that power is spread over a very large area after a short distance, and the total energy is spread out over many colors so that no one frequency (color) is bright. A 35w handheld HID might be a match for a 1mW greenie at some ranges but I'd except lasers to win in almost every other case.

But the beam on the Rescue Laser Flare IS spread out into a line. I'm sure it is bright, but so are the newer white LEDs. Both have to be aimed at the target to some extent.

The bright LEDs such *do* put out a lot more power than the Laser Flare, perhaps 250 mW of optical power vs. no more than 5 mW for the laser.

The problem is that an LED spreads that power out over all the colors instead of just the one (green) the eye sees best, and the power is spread out over a much large beam, that gets larger much faster than a laser beam.

(a Fenix and such has a beam that starts out perhaps 100x larger than a laser and it goes downhill from there - even at the start with a 50x power advantage the LED is weaker per unit area. A handheld HID might emit several watts of optical power, perhaps 1000x a laser's power, but again the beam would start out 5000x or more larger)

The Flare's beam is a very thin line that gets thicker and longer very slowly with distance. If you shine a flashlight at a wall 10' away the beam is already significantly larger than it was at the exit of the flashlight. When you project the flashlight's spot size out to a distance of several miles it's trying to fill an area vastly large than the laser's area, which won't have grown nearly as much.

I don't think it's possible to aim a laser by hand at a target over a mile away. The laser spot is so small that no hand is steady enough, not to mention that you can't see where the beam is going when trying to hit an airplane (there's nothing to reflect a miss back at you). At best I suspect you try to sweep the Flare's line back and forth over the aircraft, knowing you'll hit it at some point.

Maybe.
Would it be my preferred device?
No.
Would it be better than nothing?
Yes.

A few comments. Using a 30mW green laser in the US may get you rescued, but it will also get you arrested, The 5mW green laser flare from Greatlands, is amply powerful enough to safely signal someone over 30 miles away.

In tests we conducted, I could see the green laserflare reflecting off the water surface using NVG's when we were at 3000 ft altitude and about 37 miles away. That was with the laser not aimed at our aircraft. You could see the lines radiating out from the boat, pointing directly to it.

Regarding LED lights, the Surefire G2 LED was easily visible over 20 miles away as its reflector made an easily seen luminous dot.

Regards,

Tom A.

Yeah ... I went back to Doug's review article:

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

2 AA Mini-Mag: 6 miles
1 AAA Pelican MityLite: 9 miles
2 AAA Pelican MityLite: 12 miles
2 AA Pelican MityLite (21 lumens): 15 miles
Surefire 6P (80 lumens): 25 miles
Red Rescue Laser: 22 miles; 28 miles w/ Night Vision Goggles (NVG)
Green Rescue Laser: 30 miles; NVG not tested

The small 1xCR123 Fenix PD20 is listed at 9/47/94/180 lumens for 35/6.5/2.6/1 hours.

The Red Rescue Laser runs for 40 hours.

That would suggest to me that the Fenix PD20 on medium (47 lumens) has about the same visibility and total battery life as the Red Rescue Laser.

The 30mW Laser from dealextreme has a Kaleidoscopic feature which splits the single beam into many hundreds of beams in a Kaleidoscopic fashion (about 500 beams @ 30mW/500 or about 60 microwatts per individual beam). The multiple laser beams are divergent over an area of the sky, greatly increasing the hit probability over a single much more powerful beam (especially if the Kaleidoscopic function is used) The Greatland laser beam is also divergent in one plane and the technique to increase the chances of being seen by SAR is to move the continous divergent beam back and forth across an area of the sky, where the SAR helicopter/aircraft is located.



I'm pretty sure the Greatlands divergent laser flare works just fine once the proper technique is employed to get the laser onto the SAR helicopter/aircraft. I suspect that the Dealextreme 30mW Laser will work as well but i'm just unsure as to the effective range and probability of getting the Laser noticed. The Kaleidoscopic Laser can also be used as a single conventional single high powered beam. Any thoughts? I guess what is pretty crucial is the angular width of the Kaleidoscopic Laser pattern. At just $27 it is considerably cheaper than the Greatland Laser flare.

I suppose the only way to know is to take one out and try it with a friend. See how far away you van see it at night.

If it is visible at a decent range then the only remaining questions are about durability