Nick, I agree with you that l@ser pens are quite harmless even at quite close range, however the l@sers that are being used to target aircraft are the more powerful 'green l@sers', the ones used in astronomy to point out celestial bodies. I don't know if these are any more dangerous, perhaps some one could enlighten me. The other issue causing concern to the security forces (in my area, can't speak for others) is that l@sers can be used as rangefinders. In all probability it's kids being stupid but the possibility of terrorism cannot be discounted. Hope this makes sense, as am in a rush to get to work. Brom
well a quick look on ebay shows 50mW green l@zers available for around £20 and 2-300mW l@zers for around £100 - £150.
The latter are classed IIIB, and according to wikipedia "l@zers in this class may cause damage if the beam enters the eye directly... l@zers in this category can cause permanent eye damage with exposures of 1/100th of a second or less depending on the strength of the l@zer. A diffuse reflection is generally not hazardous but specular reflections can be just as dangerous as direct exposures. Protective eyewear is recommended when direct beam viewing of Class IIIb l@zer may occur. l@zers at the high power end of this class may also present a fire hazard and can lightly burn skin."
Now if some little s**t shines one of those in my eyes when I'm flying I'm not gonna be happy!
Brom, The Green l@sers are still <5MW, and are no higher in energy than the less visible red ones.
The panic that this thread embraces is simply awful.
"Loss of vision for 3 days" from a l@ser pointer hit in flight?? at what range - 200 meters, perhaps? Give me a break, ppng, I simply do not believe you, do you have something more than a war story to show it? Especially when the truly documented case, "Luttrulla & Hallisey (1999) describe a similar case, a 34 year old male who stared into the beam of a class IIIa red l@ser for 30 to 60 seconds, causing temporary central scotoma and visual field loss. His eyesight fully recovered within 2 days, at the time of his eye exam." ppng, tell the Doctor who certified your friend's event to write a paper on it and make a name for himself, since an airborne hit is worse than staring at a l@ser you hold in your hands!
I reiterate, the panic a pilot can feel if he believes that he has been permanently blinded, based on the myths this thread propagates might be worse than the actual flash of light, as bothersome and annoying as it is.
I edited this to add that if folks are using industrial l@sers at hundreds of mw strength, the effects are far more serious, and all bets are off, but I would also bet that pointers at <5mw are the culprit in these cases we are discussing. BTW, the Comanche design addresses these issues, and much was learned back than about protecting crews from truly dangerous l@ser light - the l@ser that can actually blind you at hundreds of meters is no hand held device, believe me!
Last edited by NickLappos; 30th Nov 2007 at 16:00.
I've heard a commercial airliner reporting to ATC that he was under attack from a powerful green l@ser and he was in the descent at around 7000ft at the time! Must have been a bloody big pen. I suppose the main gripe is that, when you are going about your lawful business trying to lock up baddies it is very distracting (with all of the inherent dangers that can bring) and definately annoying when some little oik starts playing laze the helicopter. I would imagine that a foot bobbie trying to carry out his duties would get a grip of, and have something to say to, anyone in his vicinity who was shining something as harmless as a torch in his mush as he went about his job!
This is a reply from the MOD experts after I was lased? about a month ago.
I have shown the clip to l@ser experts at DSTL and we feel that the device in question is a l@ser. The beam is very narrow and has no side lobes that would be expected if a powerful hand held lamp was used.
The pure green colour strongly suggests that it is doubled neodymium at a wavelength of around 530nm. Hand held l@sers of this frequency (colour) are readily available.
These hand held l@sers have a beam divergence of about 1mrad (milli-radian) and this is typical of l@sers readily available over the internet. At a distance of 1.4 miles (say 2.5kms) these produce a l@ser ‘splash’ of about 2.5m diameter, enough to fill the cockpit of a medium size helicopter.
The l@ser is certainly more than a typical presentation pointer. A CCD camera at a range of 2.5kms would be dazzled by a 50 to100mW l@ser at night. As the helicopter was operating in an urban environment the effect of the urban lighting would reduce the camera aperture which would indicate that the l@ser was probably nearer to the 100mW. Our assessment is that this likely to be a 100mwish l@ser operating at 532nm. Such a l@ser would have an NOHD (Nominal Ocular Hazard Distance – the distance at which you could view the beam without risk of eye damage. It would be very uncomfortable. Any closer to the l@ser increases the risk of eye damage) 70m and would definitely cause eye damage at about 25m. This is all based on experience and It would be very difficult to prove any of this from the video evidence alone. We would need to know more about the ambient illumination, particular content of the atmosphere and the camera being used.
Well, let's look at the math. 100mw over a circle 2.5m in diameter gives a power of 2 microwatts per square mm. The iris of the eye can open to 7mm at night, which is 38 square mm. The total power to the eye is then 77 microwatts, or 0.077 mw. Not enough to cause permanant damage, I think.
(Don't do math before lunch. Previous version of this post was in error)
Last edited by MarcK; 30th Nov 2007 at 19:41.
Reason: Math Error
Industrial welding CO2 and YAG l@zers (definately not hand held) would quite happily cut a car or helicopter in half if beam focused accurately enough for long enough. However the beam operates well into the infra-red, and you actually can't see it directly! You would likely never know what caused the damage.
I did not think there would be so much interest. Only posted due to personal lamping, not l@ser & it was nice to hear some get caught. Nice to know that the smaller units will not blind us just degrade our night vision for a while, great if you are flying in urban environment, with other traffic around you (news ships & police) leaves me with a real relaxed feeling, Nick I am interested to read your links, but if night vision can be degraded by l@sers of 5Mw a 2\300Mw is going to have a significantly greater effect. www.saao.ac.za/~wpk/laser/index.html and another 2\300Mw and pulsed www.wickedlasers.com/lasers/Spyder_II_GX-26-0.html This is without spending time at it I think Nick is saying that as with all beams distance \ air quality will reduce their effective power. At a distance determined by the l@ser power the effect will vary, it is at low level and high work load + darkness that the effect will be worst, the jobs that spring to mind are Police,low over built up arias SAR again low with high work load and any helios\aircraft landing
We know l@sers can be harmful to the eye and one problem is some if not many of the handheld l@sers coming out of ... well, one big country often do not comply with standards. They present stronger beams than what they are certified for and some easily exceed the limits of Class 1. Red l@sers are the considered the least harmful but then you get into the green l@sers. More powerful.. use more power and can cause more damage. Before you just write off a l@ser as some kid with a handheld and not worth your worry, visit this website. http://www.laserinstitute.org/public...r_safety_info/ A second site http://www.microscopyu.com/articles/...sersafety.html
My son just came home from a week with his mother in Thailand. In his luggage is a green l@ser, purchased in Pataya (or whatever the place is called) labelled "30mW, 532nm". It is powered by two AAA size batteries, and let me tell you, the thing shines!
We pointed it at our church across the bay, a distance of slightly less than a kilometer, and see a spot no more than an inch or two in diameter! How's that for collimation and coherence? I have never seen a LED-based l@ser with such properties.
So, rest assured. You can get these thingies with really high power really cheap - he paid £22 for it!
Needless to say, he has been given a lecture about where to point it and where to not point it...
A Bakersfield couple faces up to 20 years in federal prison for shining a l@ser light into the eyes of a sheriff's helicopter pilot.
Twenty-five year old Jared James Dooley and his girlfriend 25-year-old Christine Snow, both of Bakersfield, are charged with interfering with the safe operation of a sheriff's department helicopter. According to a federal complaint, it happened on a Thursday night in November. The l@ser allegedly disoriented the pilot causing pain and discomfort for a couple of hours.
Dooley and Snow also face a $250,000 fine. Both appeared in Federal court Monday.
http://sacramento.fbi.gov/dojpressre...7/sc121707.pdf According to the federal criminal complaint filed on December 13, on November 8, 2007, at about 10:55 p.m., a green l@ser beam illuminated the cockpit of a Kern County Sheriff’s Department helicopter, which was flying at 500 feet above ground level during routine patrol in Bakersfield, California. When the light hit the cockpit, it disoriented the Kern County Sheriff’s pilot, causing pain and discomfort in his eyes for a couple of hours. l@sers, an acronym for Light Amplification by Stimulated Emission of Radiation, pose a safety hazard to flight operations. The focused beams of a l@ser light remain powerful at extended viewing distances and can expose pilots to radiation levels above those considered to be flight safe. Brief exposure to even a relatively low-powered l@ser beam can cause discomfort and temporary visual impairments, such as glare, flash blind, and afterimages. The pilot and a tactical observer were able to pinpoint the origin of the l@ser beam at DOOLEY’s Bakersfield residence, where SNOW occasionally stayed. On November 27, task force members executed a federal search warrant, locating a hand-held green l@ser device in DOOLEY’s pickup truck and a red l@ser device in his home. Both DOOLEY and SNOW later admitted they had used the green l@ser device on the night of the incident. SNOW told investigating agents that she and DOOLEY were standing in the driveway on November 8 and “taking turns shining the l@ser around watching the tracers in the sky.”
PS But nice to see that the reporting is as accurate as ever... "Snaresbrook Crown Court was told that the helicopter was about to land on top ofthe Vanguard building in October 2006. The helipad often accommodates City figures who want quick access to Canary Wharf."