Posted on 09/28/2004 8:12:49 PM PDT by ableChair
Greta Van Susteren reported that a Delta pilot enroute to Salt Lake City was lazed in the cockpit this last Wednesday. Only country I know that has that hardware (for lazing bomber pilots) was the Soviet Union. Pilot reportedly required medical treatment and this was not a minor injury (weak laser) wound. More will come out to tomorrow as this story hits the print press.
Irrelevant and off-topic. You're talking about information transfer, not large energy transfers. Big difference.
I recall this story, as well as one wherein a private pilot was blinded by a laser in California. To be fair to the other poster(s), a high-altitude strike would require a powerful laser (and still, a direct line of sight impact on the retina). Beam dispersion at 30,000 feet would be substantial. In this regard, perhaps I owe FReeper Kirkwood an apology. I suppose I would have to run the math, for example on a 20 KW, 3-5 cm AR beam with 2% dispersion at 30,000 feet to be sure. No time for that now. :O)
I think the military developed some goggles that supposedly protect from this but still allow you to see. So, I think it can be readily defeated. Not sure, but I think that's right.
Until the air ionizes it doesn't make any practical difference.
To ionize the air with laser light it take very large energy densities.
A space heater is not radiating directed energy.
An inexpensive diode LASER rated at one (1) Watt of output (optical) power can pop balloons from across the room, and potentially start fires. An eyeball doesn't stand much of a chance against such a device, even at greater distances.
A much higher powered flash pumped LASER can be fabricated for several hundred dollars. A 30 Watt beam is capable of welding, and punching holes in razor blades/hardened steel. If you know what you are doing, you should be able to rig a 30 Watt gas or ruby (yag) LASER in your garage, on a shoestring budget. Such a homemade LASER could indeed be extremely dangerous.
Atmospheric conditions can play a significant role in diffraction but, by its very nature, a LASER beam is capable of maintaining coherency across vast distances. Even if a 10 Watt beam were 90% diffracted by the time it reached its target, you should still have plenty of coherent photons to damage an eyeball.
It would be a bit tricky, but not beyond the ability of a competant grad. student.
Even if you got lucky, the exposure would only be tens of microseconds and would be harmless.
You're thinking CW, a Q-switched laser would do the job in nanoseconds.
The bottom line is... This article is a bunch of horse puckey.
Perhaps, but if it did happen. I suspect it was a government or research system such as a GuideStar.
Your post is off-point. Read my other posts. I wasn't comparing a space heater to a laser in the way you assumed.
Nuke driven x-ray laser interception systems (maybe in the year 3000)
Not to worry, the modern Chemical Oxygen Iodine laser systems are the real deal. (hard problem as opposed to friggin buck rogers impossible)
Nice !
Thanks for the info, hope you are right.
No. That was a Canadian military helicopter. A US naval officer who was riding along suffered irreparable retinal damage due to the lazing. He's still seeking some sort of compensation.
Or some idiot thinking he could see a spot on the moon and hit a plane just right instead.
It isn't off topic.
The energy levels it takes to damage the eye are relatively low.
Path loss does not go up with an increase in power level until the air ionizes. That level of energy is huge. You'd vaporize the pilot at those power levels...
You are mixing the term "power" with the term "energy". They are not the same thing. If a laser has a very short pulses, it could have very high peak power, and yet not all that much energy or average power transmitted. OTOH, if it's a continuos laser, then the average power is the same as the peak power. Power is in watts, energy in joules (watt seconds) Thus the 50 watt laser, if continuous, delivers 50 joules every second. But if the laser has a microsecond pulse at the rate of one pulse per second, then it would take a 50 Megawatt peak power to deliver the same average power, or energy per second.
(2) When the retina is exposed to pulsed laser energy, the heat cannot be carried away quickly enough by thermal conduction. The tissue is superheated and undergoes an explosive change of state, creating shock waves which mechanically disrupt tissue and spread the area of damage. If more energy is introduced, the injured area will become larger. The mechanical force produced can blow a hole through the retina and choroid, resulting in hemorrhage and may lead to severe visual loss. The blood can collect beneath the photoreceptor cell layer of the retina, disturbing its contact with the retinal pigment epitheliums resulting in retinal detachment (Figure 4). This subretinal hemorrhage can result in the death of the photoreceptor cells and a scotoma that is much larger than the thermal burn or mechanical disruption. The blood may also move into the vitreous through the disrupted retina, where it may obstruct the passage of light through the eye (Figure 5). Extensive or centrally located hemorrhage can produce a significant loss of vision. Blood in the vitreous is absorbed very slowly, but in most cases it is absorbed. The visual impairment remains as long as the blood persists; vision may improve to normal with resorption of the blood. Persistent vitreal hemorrhage may be removed by a complicated
from : http://www.globalsecurity.org/military/library/policy/army/fm/8-50/INTRO.htm
No problem - there is a lot of hoopla out there - let me address (if I may) a couple of points that came up in the last 30 posts or so -
1) You CAN build these in your garage, as posters have mentioned, but there's no need to - you can buy them legally for less money (unless your time is totally worthless) than you can build them. They usually come with a warranty, though not a guarantee of suitability for this particular purpose!
2) Tough to defeat, if you want the pilots to be able to see through the windows - the military goggles that protect our soldiers are designed to protect against specific wavelengths - ultimately, if you want to see out the window, visible-band lasers can get IN the window. That makes this a tough problem, at least as long as the pilots are looking through the window. One solution (used for eye safety in my own lab) is to use light barriers (i.e., "walls") and then view the objects of interest with cameras. Even when a laser "paints" the camera, no one gets blinded, and the worst that happens is that a CCD array bites the dust. This kind of solution could potentially provide a countermeasure, albeit with serious consequences to things like depth perception, etc.
To ionize the air with laser light it take very large energy densities.
Yes, but I would think that the 1016W lasers people were talking about might ionize air, which would cause pretty severe attenuation. Smaller lasers aren't going to ionize air, and thus will be attenuated much less.
Laser injures Delta pilot's eye
By Bill Gertz
THE WASHINGTON TIMES
http://washingtontimes.com/national/20040928-111356-3924r.htm
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