Posted on 01/02/2005 7:16:29 PM PST by Blood of Tyrants
Just reported: An airline on approach to the Nashville airport has had it's cockpit targeted by a green laser. The plane was about 6 miles out and at 3000 feet when the incident occurred. The plane landed safely and no one was injured.
This makes SEVERAL reports of green lasers being targeted at commercial airlines in the past several days. Something really weird is going on and it is a concerted effort by several individual groups acting in concert or one very mobile unit.
http://the.honoluluadvertiser.com/article/2004/Dec/30/br/br05p.html
Bright light near airport bothers pilot
By Mike Gordon
Advertiser Staff Writer
Somewhere on O'ahu today, a homeowner is rethinking the number of outdoor lights he turns on at night after the Federal Aviation Administration and Honolulu police told him they bothered a commercial airliner pilot making his approach to Honolulu International Airport. (snip)
Right you are...the green lasers are the military variety. There have been approx. 52 incidents of this nature over the past 2 years. Additionally, the planes that have been targeted had been flying at an altitude of greater than 3000 feet. Lessens the chance of these incidents being harmless pranks or stupidity. Add to that scenario the fact that the laser directly hits the cockpit at the higher altitude, would insinuate that the tracker has some degree of sophistication...
It's hard to be effective at stopping terrorists. It's too easy to cry wolf when nothing is really happening. I think that the cops in Jersey just should have told this guy he was an idiot and let it go. Sometimes a little intelligent policing goes a long way in preventing our authorities from looking overzealous and kind of dumb.
http://orsa.blogspot.com/2005/01/beavis-and-butthead-play-laser-tag.html
Amature astronomers love the green lasers, since the beam is highly visible. Often, in an effort to show someone where to look in the sky, simply pointing your finger does not work because of paralax. By using a green laser, they can easily follow the the green beam of light and locate the star or planet that you were trying to point at.
If the pilots doing 600mph at 3000 feet he might get arrested also(max. 250kt(288mph) below 10000)
OK, 600 mph, give or take several hundred mph ;-)
Cool! Thanks! Now to get the info to Homeland Security or something...
I was thinking about picking-up one of the cheapies just to use in meetings at work (nobody else HAS a green one yet, so it would be cool!) but dare not now 'cause it'll probably put me on some homeland security "mailing list"...
Yep, I got green laser pointers for my son and grandson this Christmas. They love 'em... hope they don't get busted.
I bought a 17mW green laser at an amateur astronomy show in NY last spring. You can buy them up to 30 mW - maybe even higher. Comes in very handy when I show my son and other kids planets, constellations, nebulae, etc. Though I'm a bit paranoid to be using it right now!
I put the wrong link in that post. Here's the correct link to the Edmund Optics retro reflector page:
http://www.edmundoptics.com/onlinecatalog/Browse.cfm?categoryid=72
Warn them about pointing them at aircraft. Some children (and adults) aren't aware that it could cause a problem.
I don' think any pilots have been blinded (no retinal burning)- they are reporting seeing a bright green light, causing afterimages and temporary night vision problems (bad enough when trying to fly). You are correct, the power density over the area of the pupil is low for a 100mw laser. A 10W laser gets close to dangerous at that distance.
One safety factor with a visible laser is how much energy can you get into an eye before the eye reflexively blinks. A near-infrared laser, say 850 nm, is more dangerous than a red (633) or green (532) because you won't blink until lots of power gets in.
Even if the visible beam is spread out, it will look like a very bright light if you look into the beam. But, the spread out beam is easier to aim.
Beam divergence: There are two mechanisms that spread a beam. Up close, the beam spreads based on the optics used in the laser. In this distance, meters to hundreds of meters, the beam spreads at perhaps a milliradian or so, a very tight beam that makes lasers so useful.
There is a range at which the wave properties of light itself causes the beam to diverge, the wave wants to become spherical and the wave properties push the photons to the side. After this distance the beam spreads rapidly. This depends on the wavelength of the light and the beam diameter.
If you want to propagate a beam over a considerable distance, you first expand the beam then collimate it. A 1mm beam spreads much more than a 1cm beam does.
Thank you, I did not know that.
Or "Alan Parsons"...
Thank you. The little knowledge I had of lasers was the coffee table science book variety. This site is so cool that we can educate as well as entertain.
I was called all sorts of names for suggesting this the other day.
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