Why Protesters In Cairo Use Laser Pointers 303
New submitter Ahmed Shaban writes "Why do protesters in Cairo use laser pointers? At the beginning, they were used to light up snipers on rooftops. Later, it just became fashionable to use them, and such things spread very fast among the youth of Cairo, who can find the high power laser pointers for sale on the sidewalks. The article contains amazing photos of a chopper lit up by green laser pointers."
Re:Whats the laser used in laser wars (Score:4, Informative)
Re:Whats the laser used in laser wars (Score:5, Informative)
Atmospheric effects like fog machines and hazers are why you can see them in Laser tag.
You can see the ones in the Egypt videos because they're just really powerful. Far more powerful that what is legally available in the USA without a variance.
Re:No reason to light up snipers these days... (Score:5, Informative)
Then, they (the military) appoint some other guy to be president.
That 'some other guy' was the head of the Egyptian Constitutional Court, and a deputy chief justice for over 2 decades, not some arbitrary pick.
Re:No reason to light up snipers these days... (Score:4, Informative)
Yeah, the US traditionally champions democracy with the caveat that the people elected had better be who the US wants to see in power, or your democratic process will be summarily and violently overthrown. Egypt is just one more chapter in this book of aggression.
Re:The real idiots... (Score:5, Informative)
Re:Whats the laser used in laser wars (Score:1, Informative)
Laser Tag does not use real lasers, it is just a focused bright LED.
Re:Whats the laser used in laser wars (Score:4, Informative)
Most laserpointers are 1mW or less, so they don't reflect enough particulates in the air unless it's foggy. The green ones in the video are usually at least 5mW, which is powerful enough to reflect off enough dust in the air to be visible under normal conditions.
It's one of the big errors that scifi movies have with lasers in space combat (the other error being that laser pulses move slow enough to be seen). even with insanely powerful lasers, they'd be practically invisible in space because there's nothing for them to reflect off. Unless, of course, you want to pretend that all laser space battles take place in dust or gas clouds...
Re:uh uz they're idiots (Score:5, Informative)
If lasers are being sold for cheap on the street, odds are good that they're producing a wide range of wavelengths. The cheaper the laser, wider the range of wavelengths it emits. It's one of the reasons better lasers come with an IR filter to help reduce accidental blinding of observers.
Um, no. Not enough to say so, at least.
What makes a laser a laser is that it is a single wavelength. The light amplification process itself only works on a specific wavelength, and weeds out other light. You have to put extra circuitry into a laser to get it to produce a wider range.
Re:It's horrible they caused that helicopter to cr (Score:5, Informative)
If an aircraft is on auto-pilot, there's negligible risk.
If an aircraft is currently under human control while cruising, there's a slight risk.
If an aircraft is under human control while taking off, landing or performing any sort of maneuver, there's a reasonably significant risk.
Have you ever had someone shine a bright flashlight in your face? It's a lot like that. It causes you to jerk away, confuses you, and partially blinds you for anywhere from a few seconds to several minutes. Any of those can be deadly given that the person with the laser probably doesn't know if the aircraft is on autopilot or is preparing to land.
It's one of those laws where, sure, 98% of the time nothing bad will happen if you do it. But that last little bit of a time, something *really* bad could happen. So it's a felony.
Re:Whats the laser used in laser wars (Score:5, Informative)
Nope, just mail order that mofo. These guys sell 1W+ blue lasers:
Wicked Lasers -- any colour, any power, get em before they're gone. [wickedlasers.com]
Re:uh uz they're idiots (Score:5, Informative)
Some laser pointers do put out IR wavelengths as a byproduct of the way they're built. Low-power laser pointers aren't a problem, the IR simply isn't powerful enough to do anything. But with 100mW+ laser being sold to ordinary people, there is a very real IR hazard from cheaply-made badly-filtered (or not filtered at all) laser pointers, especially green laser pointers.
The reason it's so dangerous is that unless you have special dual-wavelength safety glasses, they'll only filter out the visible light, leaving the IR output to wreck havok on your eyes.
http://en.wikipedia.org/wiki/Laser_pointer#Infrared_hazards_of_DPSS_laser_pointers [wikipedia.org]
Re:Whats the laser used in laser wars (Score:4, Informative)
Re:Whats the laser used in laser wars (Score:4, Informative)
Oh, please.... (Score:2, Informative)
People bring up the Lincoln thing all the time (usually it's some bitter old southern racist who still hates Republicans for their "war of aggression" against his slave-owning grandpappy and who is angry the rest of the Democrats have moved-on...) but Lincoln was in an utterly unique situation (for the U.S.) which was that half the country, including parts of the military, had broken-off to form their own country over their demand that they had the right to own, and treat like cattle, another chunk of the population. At that moment in time, with even many families split by the war and brothers fighting against brothers, Lincoln was in a place never contemplated by the Constitution. if Half of America was currently Muslim-Brotherhood-aligned, blowing-up buildings and bridges, openly fighting the US military in cities around the country with hundreds of thousands of dead people and the US Military actually losing some of the battles, not many sane people would criticize a President for taking Lincoln-style actions. The criticisms of Bush43 and Obama is that they have undertaken many actions more severe than Lincoln did but without facing a threat anywhere near what Lincoln faced.
Lincoln was a good man, and his cause was entirely just. The founders of the nation tolerated slavery in the south as part of forming the union to fight for independence from King George... but they wrote at the time that they expected slavery to come to a natural end on its own. By 1860, however, it was quite clear that the Democrats were never going to give-up on owning black people and indeed they were demanding that new states added to the union be slave states. When Lincoln was elected, running as an opponent to slavery, the Democrats went crazy and split the nation over the fear he would free their slaves. They were dirtbags who deserved to lose the war. I hate sugar-coating. I'm sure some Democrat, unable to handle the truth, will flag this as a troll post... but it is a provable, well-documented FACT that no Republican ever owned a slave and nearly every slave owner was a Democrat. Indeed, after the war, it was Democrats who formed the KKK and one of the groups the KKK targeted for violence was Republicans (these too are documented FACTS.... as is this: Many Democrats currently sitting in the US Senate have knowingly cast at least one vote to have as their party Senate leader an actual Klan member (the Late Dem. Sen. Robert Byrd)).
Re:Whats the laser used in laser wars (Score:4, Informative)
Interestingly enough, the crowd on Tahrir square was actually cheering the military on. Every time the helicopters showed up it was cause for celebration. The crowd likely had no idea that they were annoying the pilots.