[MR_T3D]

just hope some mainstream news organization doesn't get wind of this and run with it.

actually, this seems like a 0.9 version of a useable infantry laser weapon system, just make it a little more powerful and maybe look like a gun, as-is it looks like the force lance from andromada, minus extension mode and it shoots beam instead of bolt, but down the line.

though the bit where it sets you on fire might not be cool with Geneva convention.

[Scotty]

So, what, is it just functionally a cross between a laser pointer and a lighter?

[redsniper]

It's just a really powerful laser.

[chief1983]

Johnny 5 is one step closer to being alive

[watsisname]

New forms of Chinese torture are being invented as we speak!    But seriously... if you have one of these in the house and your kids' friends come over and think it would be fun to blind the cat...  Well... then again... it's not like pencil torches aren't readily available and they can do just as much damage.  And they only cost $10...

AFAIK, pen lasers don't really burn skin or set things on fire.

Actually, quite a few brands of intermediate (100-500mW) lasers come with keys and a safety switch so that random people can't pick them up and use them in the name of stupid.

Flipside:  Agree 100%.  I've heard about and seen people do really dumb*** stuff with high-power lasers.  Like point them at something slightly reflective and then wonder why their eyes hurt like all hell.

Example:  friend of mine, against my better advice, tried shining a 250mW green laser at a street sign ~50ft away once.  He spent the next few minutes sitting down on the ground with his hands over his face.   His eyes turned out fine though, as I expected.  Just flash-blinded him momentarily.  

Related lesson:  Never attempt find out if a 20+W infrared CO2 laser is functioning properly by putting your hand in front of the emitter.  (ouch)

[perihelion]

Related lesson:  Never attempt find out if a 20+W infrared CO2 laser is functioning properly by putting your hand in front of the emitter.  (ouch)

****ing hell, man!  Are you serious?

I used to work in a lab where I was using a frequency tunable dye laser for induced fluorescence spectroscopy.  We used a Nd:YAG laser as the pump to get the dye to lase.  I do not remember the wattage on that YAG laser, but I can tell you that we were using a Marx bank the size of an industrial strength microwave oven (think back to your days in the college mess hall) to power it.  We needed a beam in the UV range (355 nm) to pump the dye laser, but the primary beam from the Nd:YAG is at 1064 nm before we split part of it off for frequency doubling.  The UV laser beam I needed was bright as hell, but it was only a scant fraction of the power in the infrared beam.

Once, for kicks, I scooted the beam-dump back an inch and stuck a business card into the path of the infrared beam.  I thought it would set the business card on fire.  It didn't.  The damn thing exploded.  Completely tore a hole through it.  I eventually worked out that the water in the card fibers was heated and flashed to steam so fast that the expanding steam couldn't get out of the paper fibers fast enough.  So it exploded.

I stopped screwing with the laser after that.

[NGTM-1R]

Once, for kicks, I scooted the beam-dump back an inch and stuck a business card into the path of the infrared beam.  I thought it would set the business card on fire.  It didn't.  The damn thing exploded.  Completely tore a hole through it.  I eventually worked out that the water in the card fibers was heated and flashed to steam so fast that the expanding steam couldn't get out of the paper fibers fast enough.  So it exploded.

Congradulations, you know now exactly how a weapons-grade laser works: by causing a series of vapor explosions to put a hole in the target.

[watsisname]

Related lesson:  Never attempt find out if a 20+W infrared CO2 laser is functioning properly by putting your hand in front of the emitter.  (ouch)

****ing hell, man!  Are you serious?

I used to work in a lab where I was using a frequency tunable dye laser for induced fluorescence spectroscopy.  We used a Nd:YAG laser as the pump to get the dye to lase.  I do not remember the wattage on that YAG laser, but I can tell you that we were using a Marx bank the size of an industrial strength microwave oven (think back to your days in the college mess hall) to power it.  We needed a beam in the UV range (355 nm) to pump the dye laser, but the primary beam from the Nd:YAG is at 1064 nm before we split part of it off for frequency doubling.  The UV laser beam I needed was bright as hell, but it was only a scant fraction of the power in the infrared beam.

Once, for kicks, I scooted the beam-dump back an inch and stuck a business card into the path of the infrared beam.  I thought it would set the business card on fire.  It didn't.  The damn thing exploded.  Completely tore a hole through it.  I eventually worked out that the water in the card fibers was heated and flashed to steam so fast that the expanding steam couldn't get out of the paper fibers fast enough.  So it exploded.

I stopped screwing with the laser after that.

It wasn't me personally (admittedly I'm pretty dumb, but not THAT dumb)   I read it on some site talking about laser-related accidents -- Infrared lasers specifically, since they can be pretty damn powerful as you yourself discovered.  I'd have no way of knowing for sure, but yours was probably in the >100W range if it reacted explosively with paper fiber.    Speaking of which what on earth kind of protection did you use with that thing?

[perihelion]

@watsisname: I had several sets of goggles I used depending on the frequency range of the laser I was working with.  Usually, that meant goggles that were opaque in the 220 nm to 240 nm range.  If I was doing some work where I had to adjust alignment of the beams upstream of the dye laser resonator, I'd have to change to more aggressive goggles that were opaque at 1064 nm and all harmonics (532, 355, etc).  Those goggles turned everything yellowish-orange.

Normally, the beam from the Nd:YAG was completely covered so I didn't have to use those yellow goggles.  The beam was split multiple times, and each branch had to have its own beam dump.  Those had already been purchased before I signed up for the project, so I'm not positive how they work, but I'd imagine you pick something that has near-zero reflectivity at the frequency of the beam being absorbed, good heat transfer characteristics, and good resistance to thermal shock.

The UV beam coming out of the dye laser wasn't that powerful.  We didn't have to worry about it hurting anything much other than our eyes.  You could let it hit you on the arm and not even feel it.  We deliberately attenuated the beam, not so much for safety, but because we didn't want to saturate the population we were measuring; we wanted to stay in the range where intensity response was more or less linear.

We also had to keep our optics very clean.  I probably spent more time cleaning that room than actually running experiments.  A dirty lens or mirror absorbs too much heat from the beam and either warps, cracks, or both.

[el_magnifico]

Once, for kicks, I scooted the beam-dump back an inch and stuck a business card into the path of the infrared beam.  I thought it would set the business card on fire.  It didn't.  The damn thing exploded.  Completely tore a hole through it.  I eventually worked out that the water in the card fibers was heated and flashed to steam so fast that the expanding steam couldn't get out of the paper fibers fast enough.  So it exploded.

Congradulations, you know now exactly how a weapons-grade laser works: by causing a series of vapor explosions to put a hole in the target.

So what would a proper armor against such a weapon consist of? A material with low heat transfer? A reflective material?

I know nothing about physics. Hence the question.

[chief1983]

Reflecting light is always good, but you have to be able to reflect enough of it or else you will still overheat, and likely reduce your reflective ability, which will absorb heat even faster, and then either melt or explode.

Low heat transfer might prevent water from blowing up internally but then it still has to do something with the heat at the surface.  It would likely then also need a very high resistance to heat, or some means of dissipating it elsewhere.

[perihelion]

There are several strategies that you could employ:
1) Ablative armor.  Dissipates the incoming energy from the laser by the heated portions going through a phase change and leaving the rest of the armor behind.  In this case, yes, you want something with a low heat transfer coefficient.
2) Reflective armor.  This is an ideal that is very difficult to achieve in the real world.  As soon as the armor gets dirty, you are screwed.  It is also very difficult to have near-perfect reflectivity except for very narrow wavelength ranges.  If the enemy uses multiple laser types, you'd have serious difficulty reflecting them both.
3) My preferred approach would be highly conductive armor.  Take advantage of the fact that the actual amount of power being imparted by the laser to the armor isn't that much, it is just being focused on a very small area.  Something with a very high thermal conduction coefficient can spread the incoming energy fast enough that the temperature at the location being hit by the beam doesn't get that high.

Any of these approaches can be supplemented by surrounding yourself with gas or mist which causes the beam to scatter and attenuate.

NOT an exhaustive list.

[NGTM-1R]

So what would a proper armor against such a weapon consist of? A material with low heat transfer? A reflective material?

I know nothing about physics. Hence the question.

Something ablative that vaporizes into high-albedio vapor clouds to diffract the beam, most likely.

[el_magnifico]

Which of those solutions would be more easily combined with other kinds of armor in order to achieve a more comprehensive protection? (for example, an armor against lasers and ballistics weapons).

[Kosh]

Wake me when they invent phasors.

[General Battuta]

So what would a proper armor against such a weapon consist of? A material with low heat transfer? A reflective material?

I know nothing about physics. Hence the question.

Something ablative that vaporizes into high-albedio vapor clouds to diffract the beam, most likely.

Boron armor, or a good ablative, will trip the amount of energy required to kill a target by armor vaporization. There were some pretty extensive studies done during the Star Wars program.

Mirrors aren't very effective at all.

[Titan]

You guys are such geeks 

(no offense, just funny how you almost instantly went from oooh, ahhhh to discussing military grade lasers)

[watsisname]

We know this already

space stiffies

[jr2]

Exactly how geeky are you guys?