Laser pointers and aircraft

[merphie]

I just saw news story on how they are now threatening people who point their laser pointers at air craft with the unpatriot act.

I have some questions maybe someone can answer. What would be the chance of someone pointing a laser pointer at an airplane and hitting the cockpit windows? Furthermore would the pilot notice?

We assume the plane is not landing, a perfectly clear day, moving very fast, and would be very high off the ground.

Since the windows are on the top of the plane it would have to be a considerable distance from the person on the ground doing the "pointing".

Wouldn't the laser from a low power source diffuse in such a distance and therefore not even noticed?

[LostAngeles]

The lasers that they're looking at are used for pointing at far away things, such as an astronomy proffessor using one to point out the Orion Nebula in the sky to his class.

I have four scenarios on this.

1) Because of the reports, people are actually going out and pointing the lasers for some unknown reason, but likely without malice. I'm thinking something close to, but not quite, like how the London police recieved a number of letter from "Jack the Ripper."

2) Summer of the Shark II: Winter of the Terrorist Lasers.

3) Since the reports, people are just noticing lasers in the sky more than they would have.

4) Terrorists are trying to use lasers to bring planes down.

Scenarios not in any order of liklihood.

[merphie]

Originally posted by LostAngeles
The lasers that they're looking at are used for pointing at far away things, such as an astronomy proffessor using one to point out the Orion Nebula in the sky to his class.

I have four scenarios on this.

1) Because of the reports, people are actually going out and pointing the lasers for some unknown reason, but likely without malice. I'm thinking something close to, but not quite, like how the London police recieved a number of letter from "Jack the Ripper."

2) Summer of the Shark II: Winter of the Terrorist Lasers.

3) Since the reports, people are just noticing lasers in the sky more than they would have.

4) Terrorists are trying to use lasers to bring planes down.

Scenarios not in any order of liklihood.

So we would be looking for a cargo van or 18 wheeler?

[webfusion]

The lasers that will reach that far into the sky need to have a pretty powerful energy source --- those dinky keychain gizmos ain't gonna do it.

http://ltpwww.gsfc.nasa.gov/education/gifs/degnan3.jpg
http://ltpwww.gsfc.nasa.gov/education/degnan1.html
Current projects by John Degnan include a fully automated and eyesafe Satellite Laser Ranging station called SLR2000, a Multikilohertz Microlaser Altimeter for remote 3D imaging of terrain from an aircraft, and a lab demonstration of an Interplanetary Laser Transponder for precise ranging and time transfer between the planets.

[TragicMonkey]

Originally posted by webfusion
http://ltpwww.gsfc.nasa.gov/education/gifs/degnan3.jpg

Is it just me, or does this look really cool?

It would be a great way for astronomers to get funding--they put up impressive lasers, and threaten to blast cities into nothingness if they don't pony up. "We have lasers!" is an effective argument.

Certainly I'd have been politer to my astronomy professor if I had seen him shooting beams of green light out of an observatory.

[HarryKeogh]

Originally posted by webfusion
http://ltpwww.gsfc.nasa.gov/education/gifs/degnan3.jpg


and thus, Alderan was destroyed.

[MRC_Hans]

ON keychain lasers (being fascinated with lasers since long ago, I own quite a few) ... (BTW, we can include gunsight lasers as well): These are relatively low-powered LED devices, with outputs around 5mW for gunsights, and <2mW for pointer devices. However, their coherence length and collimation is generally excellent, so on a clear night, they will be visible for miles, provided they are directed straight at you. They will look like a bright red flashlight. If you have one, try to find a really far off mirror, and shine the laser at yourself, and you'll get an idea.

However, hitting a 900kph plane several miles off (let alone the cockpit windows) with a small hand-held device is virtually impossible. Even if you had visual feed-back (but you won't be able to see the spot), it would be be extremely difficult. Of course, you might wave the beam around in the direction of the plane, and the pilot, if he happened to look in your direction, might notice a small red blink.

Show lasers, used for disco shows etc. is another matter. These devices are mains powered gas lasers and powerful enough to form a visible line of backscatter, so theoretically, you might momentarily catch a plane with it. They are bulkier that the led devices, but still hand-held class.

So in conclusion: If there are reliable, repeated reports of aircrew finding lasers directed at them, it cannot just be pranksters; it must be people with access to not only lasers in the disco show class and up, but also to some aiming devices, probably automatic or semi-automatic. Of course, I presume some deranged electronic engineer might actually build such a thing just for kicks. It is certainly posible and affordable for a private person. In fact, I have a few ideas.....

Hans

[Psi Baba]

Originally posted by TragicMonkey
Is it just me, or does this look really cool?

It would be a great way for astronomers to get funding--they put up impressive lasers, and threaten to blast cities into nothingness if they don't pony up. "We have lasers!" is an effective argument.

LOL! And I suppose they would demand "A million dollars" of funding!

Is this happening while the planes are in the air or on the ground? If it's while they are on the ground, I would say maybe presenters in airport hotel conference rooms are waving their laser pointers around, sometimes pointing them out the windows. Dumb theory, but it's mine and I'm sticking with it!

[merphie]

Originally posted by webfusion
The lasers that will reach that far into the sky need to have a pretty powerful energy source --- those dinky keychain gizmos ain't gonna do it.

http://ltpwww.gsfc.nasa.gov/education/degnan1.html
Current projects by John Degnan include a fully automated and eyesafe Satellite Laser Ranging station called SLR2000, a Multikilohertz Microlaser Altimeter for remote 3D imaging of terrain from an aircraft, and a lab demonstration of an Interplanetary Laser Transponder for precise ranging and time transfer between the planets.

That is exactly my point. I think something like that would stand out? I don't see any guessing as to where that beam came from.

[Regnad Kcin]

Originally posted by TragicMonkey
Is it just me, or does this look really cool?Hee-hee... my thought exactly, and before I read your post.

Very War of the Worlds.