Could this be a much cheaper alternative to the Greatland LASER flare for emergency signalling?

http://www.dealextreme.com/details.dx/sku.12337

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

I would never trust anything from GearExtreme with my life. I've seen several things they've sold, and lets just say they were underwhelming.

Not for USAmericans

Its hard to compare lasers without specs,
but a few in the same price range as greenland,
the range of 30mW green lasers is 10 miles,
50mW 25 miles, 80mW is 35 miles.
The greenland Green Rescue Laser Flare is 30miles.
Lasers in the price range of the one you linked to say the range "in excess of 6000 feet." which means 6001feet
So besides being apparently illegal for USAmericans to buy, they don't sound that great, but might be better than an actual flare

DealExtreme is a Chinese retailer of Chinese-made cheap gadgets. While I personally believe DX tries to operate on the same level as Western retailers when they can - in terms of truth-in-advertising etc - their Chinese suppliers are *not* particuarly honest or safety conscious.

You need to understand that the specs on DX's web pages are manufacturer claims. There's no telling how much 532nm green that "30mW" laser produces, and much more important, there's no telling how much 1064nm infrared it emits, and it's the 1064nm that's dangerous. A badly made 30mW greenie can easily put out enough 1064nm to blind you and since you can't see it you won't know until afterwards.

A red laser won't put out any infrared. Blue will. Ultraviolet lasers (parts salvaged from consumer BluRay players) won't but they have their own hazards.

Bottom line: for red it's not dangerous to give DX a try, but for green stick to someone reputable like
Atlas Nova . That link goes to a model with several beam patterns other than a point, also important for a rescue laser, and it won't leave your rescuer blind (SAR people appreciate that).

For anyone who doesn't know why the U.S. is a bit down on these green lasers, here is why http://www.photonics.com/Content/ReadArticle.aspx?ArticleID=30198

"Pilots have reported more than 900 laser incidents nationally since the Federal Aviation Administration began recording them in late 2004." (And that was dated 7-2007.)

A local schmuck kept his green laser fixed on a police helicopter so long that they were able to alert a ground patrol, who arrested the idiot.

Sue

Plan B: Take it as a given that some SOB is going to fire a beam riding missile at you and stick a H.A.R.M with a frag warhead down his or her throat.

That should discourage such behaviour quite nicely.

I'd love to know the difference in distance visibility between a upper-end LED light (like a Fenix or Surefire single CR123 version) in flashing mode and a Greatland Rescue Laser Flare.

I have both and would like to test it, but unfortunately I don't live near mountains nor do I own a helicopter (darn!). The single CR123 LED lights are VERY bright and much smaller & lighter ... and of course more multi-purpose.

Don't be so quick to judge; half of my Recyko stock is from Deal Extreme.

To some degree these are exaggerated concerns: battery-power hand-held greenies simply can't put enough energy into a cockpit to damage the eyes except at takeoff or landing & if you get lucky. The beam dispersion is too great. Loss of night vision is the only potential issue.

(my lasers have all come with beam quality measurements and it's straightforward to calculate the diameter of the laser spot at a distance and the power loss)

(not to mention the sheer difficulty of hitting a target with a narrow invisible beam - I assume a rescue laser is useless unless it has an output pattern other than a point since you can't hit a rescuer in the sky with a narrow beam)

The real risk is medical helicopters as they need to get close enough to the ground to be at risk. Other aircraft shouldn't be in that position (due to hazards to everyone on the ground when they crash into a power line etc).

Goggles that block 532nm green work very well and are inexpensive. I believe the Air Force has incorporated 532nm blocking for a while.

Infrared lasers are another story. They are extremely dangerous because the beam cannot be seen and does not trigger the blink reflex. Every DPSS laser (green, blue, yellow) has an infrared laser to power it and if it's made poorly can easily blind people. This is the reason for the FDA regs cited on the Deal Extreme site, not aircraft.

The electronics I've seen from them are all on sketchy side of bad, particularly in terms of "does it look like it will keep the water out". The few stitched items all had horrible stitching. And for the tiny number of tritium capsules that made it to the states (not their fault, in all honesty) were very dim, like they'd been sitting in a warehouse for a few half lives or there was very little tritium and a lot of something else (which I would call their fault). Those all point to a systemic QC issue, that's why I say I wouldn't trust them. If you've had better luck, all the more power to you.

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

? If a 30 mW laser adheres to all of the FDA regulations I don't see them complaining. In any case 50 mW is where things begin getting risky for someone a few feet away, never mind a distant aircraft. You'd need several hundred *watts* (at least) to blind someone 37 miles away.


How well do the NVG cope with a full moon reflecting off waves?

A 30mW doesn't adhere to FDA regs. That's why the ad says it can't be imported into the US. The LaserFlare is 5mW. Anything over that is illegal.

Important FDA Warning for all >5mW Lasers: FDA advices all customers that these lasers may be purchased only if you are NOT a citizen of the United States and you are NOT currently living in the United States.

The laser flare has the added advantage of being waterproof (claimed) to 80 feet.

I don't doubt that sooner or later, someone is going to sell a cheaper version of the green LaserFlare. I don't know how comprehensive their patent is, but I'm positive that it will be put to the test in the not too distant future and you'll see surprisingly similar/identical products being sold.

Cheers,

Tom

Well they would have to save me before they could haul my bones into court, and at that point I guess I could argue that it was done to save my life.
If it is a real survival situation them a lawsuit would be a welcome opportunity.

Not true at all! The rules require additional safety mechanisms (exit cover, lock, etc) above 5 mW but if present it's perfectly legal. I made my 175 mW "pointer" legal a while back for about $15 and a little extra length for the lock.

I don't think a single DX laser complies with the above-5mW rules, hence the warning. In the past many were found to not filter infrared at all(!) hence my warning they can be hazardous.

(the 175 mW greenie would be useless as a rescue laser as it's far too powerful)

A red Greatlands is a diode laser and inherently more rugged the the green laser, which is a DPSS and therefore more fragile. Both have a focusing optic and won't be quite as durable as an LED flashlight.

I could not find a reference at Greatlands web site as to whether the red Flare is a 650nm laser or 635nm laser. 650nm would be a lot cheaper; 635nm is 3x as visible to the human eye. NV goggles probably don't care.