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Why Protesters In Cairo Use Laser Pointers
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."
With the Egyptian military completely on board with the protesters this time around, I guess the laser pointers dont have much actual purpose anymore.
Its actually quite remarkable what is happening there. More people were protesting than had voted for the president because the president decided that their constitution didnt apply to him, so the military takes down the president in response but remarkably doesnt assume power.
How many countries actually have a military that would do this sort of thing? I'm fairly certain that mine, with a military that runs an agency well known now for violating the constitution, would not.
"His name was James Damore."
Oh wait, it didn't crash! With hundreds of pointer directed at it, it didn't crash. I'm wondering, have there been any aircraft crashes attributed to pilot blindness caused by laser pointers reported anywhere in the world? It seems to me that the prohibition has more to do with law enforcement and the military not wanting people identifying where drones are flying overhead since the actual risk to pilots seems to be non-existent.
Agreed. We use 10mW and 20mW green lasers for star pointing in astronomy. They're clearly visible to nearby users but get more than about 10-20ft away and that's no longer the case. Judging by the pictures in TFA the ones the protestors were using were probably in the 150mW+ range.
Seems the same in US too..
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.
You didn't read the article at all did you?
As crowds packed Tahrir Square in the centre of Cairo to celebrate the overthrow of President Mohammed Morsi on Wednesday night, three things filled the air - noise, fireworks and, unusually, laser beams.
Fireworks make lots of smoke
Is that not the textbook definition of a coup d'etat?
Just because a government is democratically elected doesn't mean it's a democracy. History is full of democratically elected governments that then turn into totalitarian regimes.
If Obama woke up tomorrow and ordered that all Tea Party members be arrested, I would expect our military to essentially remove him from office - in the immediate case by ignoring him, and in the longer case by Congress impeaching him and removing him from office - which would still require the cooperation of the military (they'd have to decide to listen to Congress and not the President.)
In Egypt, there isn't really a constitutional mechanism to get rid of a leader who, while democratically elected, isn't fulfilling his responsibilities as a democratic leader, so the best thing they have is the Army takes care of it.
So while this may technically be a coup in that the elected leader is being removed from office through a non-elective means, it's not necessarily undemocratic, if you believe the elected leader is abusing the freedoms of the people and the coup is to create the opportunity for someone who does respect the rights of the people to be elected.
paintball
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...
Thus the use of sandcasters in the Traveller RPG. Basically dump bags of sand into space around your ship to absorb/reflect any laser weapons.
'The tyrant will always find pretext for his tyranny.' - Aesop's Fables
What makes it a laser is how the light is produced. In most cases the lasers available to consumers are just very bight lamps with narrow bandwidth, good collimation, and not monochromatic.
It takes extra care to build a laser that produces only one frequency and even more care for the output to be coherent for any distance which is why holography and interferometry have problems with solid state lasers and gas laser are still used.
Although atmosphere does reduce the power, it's columnated light and in a vacuum anyway it would not lose any of its power. Dust, fog, humidity in the air will lower the power, but also cause you to be able to see the beam in the air. If you can't see the beam of a laser, it's likely delivering very close to 100% of its output power on target.
Years ago, when laser pointers were expensive, I had a 5mw red laser that we tested at 1/4 mile. It lit up an entire dumpster very nicely. (lenses weren't that good back then, it wouldn't hold a point for more than 25 feet or so, and TONS of scatter)
But on the other issue of power, just because it's a laser doesn't make it any more destructive than something else of the same power. A 100w lightbulb puts out 100x the power of a 1w laser pointer. And you don't see lightbulbs catching helicopters on fire. (even if focused in a spotlight) The only reason 1w lasers catch paper on fire is they're concentrating 1w of power into a 2mm x 2mm area. That would probably feel like a match at 1/2", enough to light paper. That's not going to melt metal obviously, at any range. The laser just lets you project that "half inch from a match" out several hundred yards. It doesn't make it more (or less) intense.
Somewhat back on topic though... wow.... that flight had to SUCK for those helicopter pilots. Someone hits one 727 with a laser pointer and the whole city loses their mind and the swat team rolls. That heli looks like it had 3-4 dozen green and at least two blue pointed at it. They would have to be out of their minds to look down except through cameras, and imagine the refractions going on inside the cockpit, with greens and blues scattering off all the shiny things. I bet that is an incredibly effective deterrent for the pilots.
Ironic, they sent in the helicopters as a show of force, and got driven off by the demonstrators using cheap, commonly available tech. Sort of like making the water canon truck leave by throwing rocks at it. Embarrassing.
I work for the Department of Redundancy Department.