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just brew it!
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Your very own light saber?

Thu Dec 09, 2004 4:36 pm

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Hawkwing74
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Thu Dec 09, 2004 5:00 pm

Is that real? Action Jim, please comment.
 
AMM
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Thu Dec 09, 2004 5:04 pm

It is entirely possible. Though lasers are not visible unless there is some kind of dust suspended in the atmosphere.

I would have thought it would be highly illegal to sell lasers like this to the general public though?
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JavaDog
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Thu Dec 09, 2004 5:05 pm

Can I mount that on my Dashboard?
 
JavaDog
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Thu Dec 09, 2004 5:06 pm

AMM wrote:
Though lasers are not visible unless there is some kind of dust suspended in the atmosphere.


Not quite true.
 
AMM
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Thu Dec 09, 2004 5:07 pm

Ah found this on the website.

This laser is not legal to use in public, and while we are not asking for any proof that the buyer is qualified to own this device, we trust that it will be used in a responsible fashion.
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Arkwald
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Thu Dec 09, 2004 5:08 pm

If this was real why is it they said:

This is a legitimate high-power laser instrument. It will cast a dot on the clouds and burn a hole through a plastic cup from across the room. It is guaranteed to be above 50mW in output power, but that is a very conservative power rating. In actuality, these lasers usually have an output between 100mW and 150mW, or even more.


Kind of a large range of output for a standardized mass produced product. Don't you think? Something is fishy about this... and I don't mean the poor flounder they just fried:)
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AMM
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Thu Dec 09, 2004 5:11 pm

JavaDog wrote:
AMM wrote:
Though lasers are not visible unless there is some kind of dust suspended in the atmosphere.


Not quite true.


Well okay, air molecules can scatter some photons... I was thinking of a laser in a vacuum.
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Thu Dec 09, 2004 5:15 pm

Air has some loss to it, therefore it will reflect back a minute amount of light. I have seen pictures of CO2 lasers that could ionize a path of air through which they passed. Very lossy, but it takes many watts of power concentrated in a very narrow beam to do it. Some guys are then using this ionized channel to dump huge amounts of high voltage high current down the path to destory objects remotly.

If you took out the crystal that converts the IR to green, this probably has a 1/2 watt laser diode behind it. The conversion to green from IR isn't very efficient. The problem is that IR lasers are very dangerous to play with without eye protection. You can't tell you are getting blind spots until you have them, and it is too late then.

If I only had $1000 dollars to dump on this. Nifty. However I could make a ruby/yag laser for much less cost, and much higher peak power (kW or more!)

-LS
 
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Thu Dec 09, 2004 5:17 pm

a mere kW? How do you get a MW laser?:)
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Thu Dec 09, 2004 5:24 pm

Yeah, you know that a laser with the power of a few watts can reach the moon, right? Aside from the gov't ban on shining lasers into the air...
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Thu Dec 09, 2004 5:49 pm

LS- You're hired.

I can tatoo my name into peoples heads from a few hundred feet away right?

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Thu Dec 09, 2004 5:56 pm

this is similar to an episode of the tick.
have you seen it
 
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Thu Dec 09, 2004 7:19 pm

Tick removal is only one of many uses of this fine product.
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Skyline57GTR
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Thu Dec 09, 2004 7:25 pm

yes, it is real. But that's not enough thick the laser light, I mean its very thin laser light. :-?
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Thu Dec 09, 2004 7:30 pm

Skyline57GTR wrote:
yes, it is real. But that's not enough thick the laser light, I mean its very thin laser light. :-?


Pardon?
 
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Thu Dec 09, 2004 7:33 pm

Skyline57GTR wrote:
yes, it is real. But that's not enough thick the laser light, I mean its very thin laser light. :-?


Well, you could use a beam spreader to achieve the perceived width of a light sabre, but only at the cost of reducing peak brilliance. The flux concentrated in that pinhole beam, once spread over a vastly greater area, will be nothing more than a big green flashlight.

Assume the hole in the cup is 1mm. Assume that a light sabre blade is 50mm (2 inches +/-) in diameter. Applying basic math tells me that the light sabre's flux per square millimeter is 1/2500 of the original laser. Yawn.
Last edited by Captain Ned on Fri Dec 10, 2004 7:15 am, edited 2 times in total.
And then of course I've got this terrible pain in all the diodes down my left hand side.
 
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Thu Dec 09, 2004 7:41 pm

Hawkwing74 wrote:
Is that real? Action Jim, please comment.


Sure, it's real.

Arkwald wrote:
a mere kW? How do you get a MW laser


Pulse it. Remember, Power = Energy/time. To increase the power, you can either push up the energy or decrease the time of the laser pulse.

As an example:
http://optics.org/articles/news/10/11/8/1

In initial tests with the Teramobile firing 250 mJ pulses centered at 800 nm, the R-FIBS system successfully detected copper and steel samples located 90 m away. The laser's repetition rate was 10 Hz with a minimum pulse duration emitted of 80 femtoseconds. The researchers say a beam profile containing around 30 filaments was typically incident on the sample giving an intensity of around 10^13 W/cm2.
Good bye everyone.
 
just brew it!
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Thu Dec 09, 2004 7:43 pm

Captain Ned wrote:
Assume the hole in the cup is 1mm. Assume that a light sabre blade is 50mm (2 inches +/-) in diameter. Applying basic math tells me that the light sabre's flux per square millimeter is 1/62500 of the original laser. Yawn.

It's probably even worse than that. The original beam is probably smaller than the hole in the cup because A) the laser was hand-held, and so probably moved around a bit during the demonstration; and B) the plastic probably melted back a bit from where the laser actually hit it.
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Thu Dec 09, 2004 9:30 pm

I know I could come up with some very good uses of that.... not saying anything.
 
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Thu Dec 09, 2004 10:15 pm

just brew it! wrote:
It's probably even worse than that. The original beam is probably smaller than the hole in the cup because A) the laser was hand-held, and so probably moved around a bit during the demonstration; and B) the plastic probably melted back a bit from where the laser actually hit it.


Bloody pedants. :wink: :wink: :wink:
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Thu Dec 09, 2004 10:56 pm

Huh Huh I wanna fry some bugs with it huh huh

:lol:
 
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Thu Dec 09, 2004 11:20 pm

AMM wrote:
JavaDog wrote:
AMM wrote:
Though lasers are not visible unless there is some kind of dust suspended in the atmosphere.


Not quite true.


Well okay, air molecules can scatter some photons... I was thinking of a laser in a vacuum.


But does it scatter enough air molecules to the laser to be detected.
have you seen it
 
just brew it!
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Thu Dec 09, 2004 11:23 pm

Captain Ned wrote:
Bloody pedants. :wink: :wink: :wink:

Hey, be happy I didn't point out your "basic math" error. :wink:
The years just pass like trains. I wave, but they don't slow down.
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Thu Dec 09, 2004 11:37 pm

Could I use this on those guys who always talk during a movie. Maybe burn a hole in the back of their head?
 
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Fri Dec 10, 2004 12:54 am

If you want one, buy now, as these may not be on the market forever.

http://www.cnn.com/2004/US/12/09/terror ... index.html
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AMM
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Fri Dec 10, 2004 4:19 am

I get to play with lasers and make holograms at university next term. Far more interesting than blinding people.
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Fri Dec 10, 2004 4:50 am

AMM wrote:
I get to play with lasers and make holograms at university next term. Far more interesting than blinding people.


Debatable, who you are blinding is the key.
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Fri Dec 10, 2004 9:44 am

Interesting link pyrodeus. Crashing planes by shining bright lights at the cockpit to blind the pilots is used in the same Tom Clancy series in which a plane is crashed into the Capitol (all written before 9/11).

Of course, the pilots could always do what the Vulcan bomber pilots were meant to do and wear an eye patch. They idea there was that after being blinded by the flash of a nuke they just reached up and swapped the patch from one eye to the other. The co-pilot would have his windows blanked out during this so they actually had 4 flashes before flying blind!
 
just brew it!
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Fri Dec 10, 2004 9:48 am

The FDA is apparently none too pleased either:
http://www.fda.gov/foi/warning_letters/g4598d.htm

(According to Dan's Data, the device mentioned in the FDA warning letter is the same one being sold on the Lasershoppe site.)
The years just pass like trains. I wave, but they don't slow down.
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