# Would this laser rifle really work? **URL:** \ **Category:** Factual Questions\ **Created:** [April 2, 2003, 7:11pm UTC](https://boards.straightdope.com/t/would-this-laser-rifle-really-work/166025 "2003-04-02T19:11:59Z")\ **Posts on this page:** 20\ **Page:** 1
**Author:** ![Second](https://avatars.discourse-cdn.com/v4/letter/s/9e8a1a/32.png) [@Second](https://boards.straightdope.com/u/Second)\ **Post date:** [April 2, 2003, 7:11pm UTC](https://boards.straightdope.com/t/would-this-laser-rifle-really-work/166025/1 "2003-04-02T19:11:59Z")
I tried a search and I did not find any relevant results. But a [story](http://slashdot.org/articles/03/04/02/1311219.shtml?tid=159&tid=103) on slashdot mentions a [laser rifle](http://www.defensereview.com/352003/TIS1.pdf) being developed by a company named Stavatti. I though laser’s needed huge power supplies, is what’s laid out in the spec sheet workable? ---
**Author:** ![3.885AM](https://avatars.discourse-cdn.com/v4/letter/3/58956e/32.png) [@3.885AM](https://boards.straightdope.com/u/3.885AM)\ **Post date:** [April 2, 2003, 7:28pm UTC](https://boards.straightdope.com/t/would-this-laser-rifle-really-work/166025/2 "2003-04-02T19:28:12Z")
Po-210 power source? “Tactically superior to all future weapon systems potential US/NATO adversaries will ever consider developing”? Trips my bullshit detector! ---
**Author:** ![CalMeacham](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/calmeacham/32/35_2.png) [@CalMeacham](https://boards.straightdope.com/u/CalMeacham)\ **Post date:** [April 2, 2003, 7:56pm UTC](https://boards.straightdope.com/t/would-this-laser-rifle-really-work/166025/3 "2003-04-02T19:56:54Z")
It’s supposed to be a gas dynamic CO2 laser. That implies that you’ve got a lot of gas flowing. This looks like a rifle-sized contraption. Where’s all the flowing gas? I’ve worked with gas dynamic CO2 lasers – you usually pump them with the instantaneous discharge of a rather large capacitor, which itself needs to be charged by a power supply. I don’t see it here, and I can’t believe you’ve got the space for it. CO2 lasers are tyopically a few percent efficient, which means you’ve got to input 20-100 times the output power in the form of your electrical discharge. As mentioned above, you need pretty good cooling for your laser (to remove the 95% + energy that goes into heat). Where is it? That tiny liquid cooling system? Somewhere or other you’ve got to vent that heat to atmosphere, if you’re not dragging around a circulating water supply. Naah, I don’t buy it. Have a look at Jeff Hecht’s book **Laser Weapons**. It’s old, but the basic principles haven’t changed. ---
**Author:** ![Happy\_Fun\_Ball](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/happy_fun_ball/32/17664_2.png) [@Happy\_Fun\_Ball](https://boards.straightdope.com/u/Happy_Fun_Ball)\ **Post date:** [April 2, 2003, 8:18pm UTC](https://boards.straightdope.com/t/would-this-laser-rifle-really-work/166025/4 "2003-04-02T20:18:44Z")
Whatever! This seems to me to be crap. Unfortunately I don’t know enough about thermo and fluid dynamics to refute there “hypersonic” gas expansion scheme. Even if it is valid, I do not understand how this would create a population inversion of a vibrational energy state. If this actually does create the necessary population inversion, the 10.6 micron wavelength (near infra-red) seems to be (at least to me) too energetic to be associated with a vibrational mode of any of these molecules (CO2, N2). Another thing that strikes me is they state: > [@](#): > > \with a net energy output to target of approximately 1.9 kW. Any real designer would not confuse energy with power. If the 0.35 second pulse has a average power of 1.9 kW, then the energy in the pulse is 665 J, which is respectable, but still… Enough about that, one thing that I can do is a back of the envelope calculation regarding the effective weapon range. A laser produces a gaussian beam, which they say has a (waist) diameter of 1.3 mm. They claim the weapon would be effective to 1500 meters. After a quick calculation the diameter of the beam at this point is (approximately) 2 w(z) = 2 w[sub]o[/sub] z/z[sub]o[/sub] =7.79 meters. This gives a beam area of roughly 760 m[sup]2[/sup]. Assumming the average power is 1.9 kW, the power per unit area of the beam is only 0.25 mW/cm[sup]2[/sup], which is hardly lethal. Sounds like a laser pointer to me. ---
**Author:** ![Second](https://avatars.discourse-cdn.com/v4/letter/s/9e8a1a/32.png) [@Second](https://boards.straightdope.com/u/Second)\ **Post date:** [April 2, 2003, 8:21pm UTC](https://boards.straightdope.com/t/would-this-laser-rifle-really-work/166025/5 "2003-04-02T20:21:03Z")
I just remembered it is/was april fools day. Perhaps a joke? ---
**Author:** ![Happy\_Fun\_Ball](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/happy_fun_ball/32/17664_2.png) [@Happy\_Fun\_Ball](https://boards.straightdope.com/u/Happy_Fun_Ball)\ **Post date:** [April 2, 2003, 8:26pm UTC](https://boards.straightdope.com/t/would-this-laser-rifle-really-work/166025/6 "2003-04-02T20:26:20Z")
Oops, looking over what I typed I’m not sure where I got that diameter. The beam diameter should be 31.2m, the other numbers are correct. ---
**Author:** ![Nanoda](https://avatars.discourse-cdn.com/v4/letter/n/ce73a5/32.png) [@Nanoda](https://boards.straightdope.com/u/Nanoda)\ **Post date:** [April 2, 2003, 11:21pm UTC](https://boards.straightdope.com/t/would-this-laser-rifle-really-work/166025/7 "2003-04-02T23:21:29Z")
“it is estimated that the weapon will deliver a recoil force of approximately 90lbs in the forward direction upon discharge” Uh huh… right. Great laser you got there. BTW, there _is_ a [stavatti.com](http://www.stavatti.com/launch_vehicles.html). Their web design is crap, and (to me) screams “fake!”, but nobody would go to the trouble of faking _that many_ pdfs… plus all the places that link to it are genuine. If it actually _is_ real, they’ve apparently hired document writers who learned their art reading AD&D manuals. I’m surprised there isn’t an index for how many D6 MD, plus necessary skills to use. ---
**Author:** ![Bill\_H](https://avatars.discourse-cdn.com/v4/letter/b/a5b964/32.png) [@Bill\_H](https://boards.straightdope.com/u/Bill_H)\ **Post date:** [April 3, 2003, 12:01am UTC](https://boards.straightdope.com/t/would-this-laser-rifle-really-work/166025/8 "2003-04-03T00:01:30Z")
uh… This is just a proposal for a future weapon; not something that’s being built today, or even considered for building soon. From Defense Reviews own description (bolding my own): > [@](#): > > Stavatti Tactical Infantry System-1(TIS-1) Gasdynamic Laser Rifle “White Paper”. > DefRev has obtained the original “white paper” proposal that was submitted to the U.S. Army for the Stavatti TIS-1 (Tactical Infantry System-1) Gasdynamic Laser Weapon. The TIS-1 is a laser rifle that utilizes a hypersonic jet of gas to create photonic energy in the form a very powerful laser. Thus the term “gasdynamic”. The Stavatti TIS-1 was submitted as a possible technology for the U.S. Army’s LFLAN requirement. “LFLAN” stands for “Light Fighter Lethality After Next”. **LFLAN involves small arms technology proposals that would not be implemented until 15-25 years down the road.** In other words, truly futuristic technology. > > Before a weapon like the TIS-1 could be adopted, a number of technichal hurdles would have to be successfully negotiated, such as… ---
**Author:** ![Q.E.D](https://avatars.discourse-cdn.com/v4/letter/q/51bf81/32.png) [@Q.E.D](https://boards.straightdope.com/u/Q.E.D)\ **Post date:** [April 3, 2003, 12:31am UTC](https://boards.straightdope.com/t/would-this-laser-rifle-really-work/166025/9 "2003-04-03T00:31:38Z")
> [@](#): > > \*Originally posted by Eyer8 \* > \*\*Oops, looking over what I typed I’m not sure where I got that diameter. The beam diameter should be 31.2m, the other numbers are correct. \*\* Neglecting collimation optics, of course, which the link doesn’t discuss. ---
**Author:** ![CalMeacham](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/calmeacham/32/35_2.png) [@CalMeacham](https://boards.straightdope.com/u/CalMeacham)\ **Post date:** [April 3, 2003, 12:07pm UTC](https://boards.straightdope.com/t/would-this-laser-rifle-really-work/166025/10 "2003-04-03T12:07:50Z")
Been thinkin’ about this on my drive in. I’ll have to look over the PDF file again, but there’s no way this can be a _gas dynamic_ laser. I used to work at the company where the Gas Dynamic laser was invented. The whole point of a GDL is to clear out the exhausted lasing material rapidly and replace it with fresh laser material. I’ve built GDLs with laser resonators about the size of a rifle – the sucker’s are BIG. Too big to carry. Here’s why =-- you typically have to have three different systems aligned along three mutually perpendicular axes. You’ve got the laser axis, of course. Then you’ve got the flow axis perpendicular to that, along which your gas flows. You need fans to drive the gas and a reservoir for the fresh gas. I don’t see any of that on the rifle. Finally, you need an excitation axis along the third direction that provides the electrical input to excite your gas to higher electronic states. I don’t see that, either. Again, as I noted above, you need a rapid discharge for your short burst. No battery is going to do that, not even a “polonium” battery. You need a capacitor, and a pretty big one, at that. I don’t see that on the rifle, either. (And it will take some time to charge that capacitor, too. This wouldn’t be a rapid-fire device). Our device ended being the size of a kitchen garbage can. You could carry it, I guess, but it’s not a weapon you’d want to use, or march with, or charge with (imagine charging with a garbage can half full of water). I’ll take a club instead any day. ---
**Author:** ![El\_Marko](https://avatars.discourse-cdn.com/v4/letter/e/58956e/32.png) [@El\_Marko](https://boards.straightdope.com/u/El_Marko)\ **Post date:** [April 3, 2003, 2:55pm UTC](https://boards.straightdope.com/t/would-this-laser-rifle-really-work/166025/11 "2003-04-03T14:55:25Z")
Okay, I haven’t read the whole thing yet (I have trouble wading through even 5 measly pages of crap in one sitting) but here are a few initial thoughts: 1: The claim is made that the “laser beam” (think Dr. Evil here) is monochromatic - I think that’s the right word - or single wavelength, yet it is produced by lasing a mixture of three different gases. This is impossible and anyone with a decent understanding of basic light physics should know it. See [this link](http://www.llnl.gov/nif/library/aboutlasers/how.html) for the explanation if you want it. 2: They claim that the energy used to produce the laser will be in the form of heat. This is also a crock. The word laser stands for **Light Amplification** by Stimulated Emission of Radiation. Note the word amplification i.e. boosting, not generation. Basic laser operation requires that you put light (not heat) in in order to get light (a lot more light) out. 3: Lethal laser output similar, perhaps, to the kinds of industrial lasers used to cut metal, comes in the form of a “pulse” or “micro-pulse” laser. This means that the energy of the laser is delivered in an extremely short (read femptosecond) timeframe. A burst lasting 0.35 seconds as detailed in the paper would have the effect of warming your skin at best. Conclusion: If this thing worked, which it won’t, the best you could do is get it in the other guys eyes and damage his retinas. This isn’t a “Star Wars” stormtrooper rifle. At best it’s a really big laser pointer… that doesn’t work! 😃 ---
**Author:** ![CalMeacham](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/calmeacham/32/35_2.png) [@CalMeacham](https://boards.straightdope.com/u/CalMeacham)\ **Post date:** [April 3, 2003, 4:29pm UTC](https://boards.straightdope.com/t/would-this-laser-rifle-really-work/166025/12 "2003-04-03T16:29:00Z")
Just a quick note here: > [@](#): > > 1: The claim is made that the “laser beam” (think Dr. Evil here) is monochromatic - I think that’s the right word - or single wavelength, yet it is produced by lasing a mixture of three different gases. This is impossible and anyone with a decent understanding of basic light physics should know it. See this link for the explanation if you want it. I’m afraid I have to disagree with you here. An awful lot of gas lasers use gas mixtures. There are a lot of reasons for this – sometimes one gas gets excited by the electric discharge, thenm transfers the energy to the other. Sometimes you add some gas to depopulate the lower level to keep up the population inversion. Heck, the Helium-Neon (HeNe) laser, which used to be the most common laser (red line) uses two gases. The gas mixture given on the page is a not atypical one for a CO2 laser. We used to make up three component mixes for our CO2 lasers all the time. ---
**Author:** ![El\_Marko](https://avatars.discourse-cdn.com/v4/letter/e/58956e/32.png) [@El\_Marko](https://boards.straightdope.com/u/El_Marko)\ **Post date:** [April 3, 2003, 4:34pm UTC](https://boards.straightdope.com/t/would-this-laser-rifle-really-work/166025/13 "2003-04-03T16:34:21Z")
I stand corrected. My Bad. :smack: I still stand by my other two points though. ---
**Author:** ![Bill\_H](https://avatars.discourse-cdn.com/v4/letter/b/a5b964/32.png) [@Bill\_H](https://boards.straightdope.com/u/Bill_H)\ **Post date:** [April 3, 2003, 9:58pm UTC](https://boards.straightdope.com/t/would-this-laser-rifle-really-work/166025/14 "2003-04-03T21:58:35Z")
uh… Did anybody read my post? This isn’t a real weapon, or even a plan for a real weapon. It’s a proposal for something that technology may enable in 20 years. It’s just a vision for a potential future put together by a respectale arms dealer (if there is such a thing) for military arms consumers to evaluate to see if they see value. If by chance the consumers do see value, they’ll start working on a real plan to get something along the lines of this proposal. Anybody who’s worked with things that are by design 20 years away knows that when 20 years comes and goes, a lot of technology will enable things that aren’t possible today, and a lot of your needs will change as well, so the reality when it comes together could be quite different from today’s proposal. This is just a potential goal. ---
**Author:** ![Bill\_H](https://avatars.discourse-cdn.com/v4/letter/b/a5b964/32.png) [@Bill\_H](https://boards.straightdope.com/u/Bill_H)\ **Post date:** [April 3, 2003, 10:26pm UTC](https://boards.straightdope.com/t/would-this-laser-rifle-really-work/166025/15 "2003-04-03T22:26:54Z")
Let me put that in the obvious way: Imagine this is 1983. The hot computer is the IBM PC/XT, which goes a blazing 4.77 MHz. Further imagine someone posts a message reading “Would this computer really work?”, with a description of a computer with a 2 GigaHz processor. Would that imaginary computer work? well, not today (1983), but it isn’t designed for today. It’s designed for 2003, when the twentieth century is a mere memory. ---
**Author:** ![jnglmassiv](https://avatars.discourse-cdn.com/v4/letter/j/f07891/32.png) [@jnglmassiv](https://boards.straightdope.com/u/jnglmassiv)\ **Post date:** [April 4, 2003, 10:43pm UTC](https://boards.straightdope.com/t/would-this-laser-rifle-really-work/166025/16 "2003-04-04T22:43:36Z")
When I first read the OP, I thought of chemical lasers. My understanding of this type of laser system is that they do not fundamentally require the electrical supplies. They instead mix certain exotic chemicals that react with each other and release, at times, huge amounts of energy. Using this type of laser might get around the large battery or capacitor stumbling block. Perhaps the proposed rifle contains little reservoirs of very efficient chemicals. That said, I don’t think any current chem lasers are anything approaching handheld. And I have also heard that the chemicals often used in DoD lasers, for example, are extremely dangerous and would be needed in larger quantities than a rifle might house. Either way, a laser rifle is a long way off. ---
**Author:** ![Tuckerfan](https://avatars.discourse-cdn.com/v4/letter/t/eada6e/32.png) [@Tuckerfan](https://boards.straightdope.com/u/Tuckerfan)\ **Post date:** [April 5, 2003, 12:00am UTC](https://boards.straightdope.com/t/would-this-laser-rifle-really-work/166025/17 "2003-04-05T00:00:31Z")
> [@](#): > > \*Originally posted by CalMeacham \* > \*\*Our device ended being the size of a kitchen garbage can. You could carry it, I guess, but it’s not a weapon you’d want to use, or march with, or charge with (imagine charging with a garbage can half full of water). I’ll take a club instead any day. \*\* “There goes the supertechnological soldier, staggering cumberously forward to wreak destruction on anyone he can entice within range. . . Meanwhile, the despicable enemy has opened fire with an old-fashioned but extremely cheap and efficient sub-machine gun.”–David Langford, _War in 2080_. ---
**Author:** ![CalMeacham](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/calmeacham/32/35_2.png) [@CalMeacham](https://boards.straightdope.com/u/CalMeacham)\ **Post date:** [April 5, 2003, 3:31am UTC](https://boards.straightdope.com/t/would-this-laser-rifle-really-work/166025/18 "2003-04-05T03:31:11Z")
> [@](#): > > When I first read the OP, I thought of chemical lasers. I did, too, but then I reread it – “gas dynamic laser” isn’t a chemical laser – it’s a system in which the lasing gas is circulated rapidly so that the inversion-killing “garbage” is whisked quickly away. So it’s a system like the one I describe above. Not that a chemical laser rifle would be any better. They require big gas reservoirs, because once you ue up a charge, that’s it – you flush out the old gas and use a new fill for the next shot. A portable chemical laser could maybe get off one shot. Maybe. ---
**Author:** ![Jumping\_Bean](https://avatars.discourse-cdn.com/v4/letter/j/dec6dc/32.png) [@Jumping\_Bean](https://boards.straightdope.com/u/Jumping_Bean)\ **Post date:** [April 5, 2003, 3:55am UTC](https://boards.straightdope.com/t/would-this-laser-rifle-really-work/166025/19 "2003-04-05T03:55:02Z")
Apart form the fact that they have a certain “gee-whiz” sci-fi mystique to them reinforced by countless films I’ve never understood what the appeal of a laser weapon would be. If you were able to pack that much energy into portable package couldn’t you find a more lethal way to deliver it than by punching small fully cauterized holes into people? Seems like even an immensely powerful laser weapon wouldn’t be able to inflict the kind of nasty sucking chest wounds that a present day machine-gun round could. I would be curious to hear if anyone thinks that, even leaving power consumption aside, one could make a laser weapon that could compete with good ole fashioned kinetic force. ---
**Author:** ![scr4](https://avatars.discourse-cdn.com/v4/letter/s/59ef9b/32.png) [@scr4](https://boards.straightdope.com/u/scr4)\ **Post date:** [April 5, 2003, 5:44am UTC](https://boards.straightdope.com/t/would-this-laser-rifle-really-work/166025/20 "2003-04-05T05:44:48Z")
> [@](#): > > \*Originally posted by Jumping Bean \* > **Apart form the fact that they have a certain “gee-whiz” sci-fi mystique to them reinforced by countless films I’ve never understood what the appeal of a laser weapon would be.** There are a few minor advantages. It’ll be easier to aim because a laser beam will not be affected by wind and gravity, and will have essentially infinite speed. So what you see on the scope is exactly what you’ll hit, and with some electronics you can hit fast-moving targets. There is negligible recoil, and with the right optics the range is only limited by line of sight. For those reasons, it makes sense for an airborne missile defence system (or so the Pentagon thinks, anyway). But energy density is a big problem, I think. It’s hard to beat the energy density and efficiency of gunpowder. And reflective armor can easily reflect 90% of the incident energy. (In theory you can get much higher, but it’ll be difficult and expensive to maintain.) [Next page](https://boards.straightdope.com/t/would-this-laser-rifle-really-work/166025.md?page=2)