Slashdot Mirror
Laser System to be Tested in Boulder, CO
luv_jeeps writes "Ball Aerospace is going to test fire a laser beam on Sunday night, as part of the CALIPSO project. If you live in the Colorado/Wyoming area, chances are good that you could see it. The article, a little light on details, says that the beam could be as big around as a basketball hoop."
The article says it's "about 40,000 times more powerful than a laser pointer", and 40k*5mW=200 watts. Since the beam diameter is "the size of a basketball hoop", nothing would be bursting into flames, although serious eye damage - to birds or pilots - could result.
Although come to think of it, for a LIDAR application I guess the beam is probably pulsed, so the situation is a bit more complicated. At any rate there's a safety shutoff mechanism as someone else pointed out.
Actually (from the project info page):
Ball will provide an active sensor that probes the atmosphere with green and infrared laser light
They're using IR (almost certainly 1064 nm) and green (almost certainly 532 nm) beams.
Yes the Satellite may have Infared on it but it also has Lidar which is Laser Radar. My local university has a lidar setup (or the green beam as its called around here). See the Utah State University link below.
Its used for atmospheric observations.
Utah State University - This page seems to be down at the moment
University of Western Ontario - Here is another University with one
The "common laser pointer" they talk about is one milliwatt(mW). That means their laser is 40W, common in industrial laser applications.
A lightning bolt contains roughly enough power to light an entire city for a second or two; it's about a million volts, and about 10,000 amps on average. That's a -trillion- watts. We're talking a MINOR difference in scale here, my friend. A lightning bolt makes a noise because it turns the air around it into superhot plasma, along with any moisture(which expands thousands of times its original volume when vaporized).
If the satellite were to receive that much energy, it'd explode instantaneously, and no, you -wouldn't- hear it, it's in SPACE, there's no AIR, so there's no SOUND- just wanted to get that straightened out, since you seem to have slept through most of your high school and college science classes.
I cannot -believe- the parent got modded up...
Please help metamoderate.
"The laser system is equipped with radar that will shut down the system in the event that an object is about to enter the laser beam."
How does it work? Does it work? I don't know, but those are the precautions they say they've taken.
"How to Do Nothing," kids activities, back in print!
you're thinking of red lasers. Red light passes through air much better than the higher frequencies (blue, green, yellow, etc). A great example of this is the color of the sky. Light from the sun passing through the atmosphere has its blue components scattered much more readily than the lower freqency components, so you see the sky as being blue. When the sun is rising/setting you see the sky as red because red light isn't scattered well the red light that reaches your eyes is much more intense
so, why are these people using green light that they know will be scattered? Because that's exactly what tells us stuff about the atmosphere!how much was scattered at position x compared to position y? how much was scattered at time t1 as compared to time t2?
The pollution causes more light to be scattered, for sure, but that's not WHY you see the light. Rest easy :)
There's a PDF here that describes the prototype laser as delivering 110 mJ per pulse. At 20 pulses per second, that's about 2 watts average power--but of course the peak power in each (short) pulse will be much higher.
~Idarubicin