Feasibility of Destructive High-Wattage Laser Arrays

Probably the most helpful comment so far. Definitely going to have to look into diffraction gratings more deeply, but I don't like the sound of that word "diffraction".

(Most of you will probably discover that I'm currently a total novice in this field. If it seems like if I've only spent 3 days thinking up this idea and researching lasers in general, that's because such an evaluation would be totally accurate. Sorry!)

So, are these folks talking about combining different laser beams perfectly? Like absolutely perfectly? Like "reading a disc/interplanetary communication" perfectly? Do we need that kind of accuracy for an idea like this? Won't the beams still transfer their net total of energy if we get them to the holy grail of "close enough"? I totally understand that "close enough at three feet" and "close enough at 25-150 yards" are totally different things and that one will be much more difficult than the other...

...I'm now thinking about using a some kind of range-finder (yay, more lasers)--like those used to auto-focus digital cameras--to automatically position that second lens such that the beams converge (close enough) on the target without needing to be perfectly straightened when they exit the second lenses. That makes it a more complicated device than I had hoped, but a potentially easier to build and use device nonetheless.

There are 3 and only 3 ways to combine beams: knife edging, PBS cube, Dichro. Knife edging doesn't combine the beams, it just gives you a larger beam the size of all of them combined, with the Dichro you combine 2 beams of different colors, it passes one color and reflects the other, the PBS cube combines 2 and only 2 beams and what comes out can't be combined with anything else. Light can only be polarized 2 ways and the 2 beams combined have to be polarized differently, when it then exits the cube the beam is already polarized both ways so it can't be combined again with another beam. You can however knife edge 2 groups of beams and then combine the 2 beams, this will still give you a large beam.

This subject has come up here many times before and people never believe it, they always think with the right optics you can combine any number of beams but it isn't so.

You also want to keep the optics to a minimum, each additional optic: half wave plate, PBS, Dichro, FS mirrors, lenses, every single one will cause a power loss.

Alan

Forgetting for amoment the legal issues of whether such a device could ever be used at any time, even by military during a war, given that blinding laser weapons have been added to the list of weapons that are prohibited weapons under international humanitarian law.
Undoubtedly, a device using several diodes can be created relatively easily, given the will, time, and money to do it, that results in a powerful handheld beam as ricktrent4 has done. It would mostly just be an illegal to use hazard to people's eyes/menace to eyesight--a powerful blinding device--yes sure, but why?

Whether you can create a "weapon" with more "destructive" potential or power than a box of kitchen matches --- that is another story--not so easy.

Pi R Squared said:

This subject has come up here many times before and people never believe it, they always think with the right optics you can combine any number of beams but it isn't so.

Click to expand...

Encap said:

Undoubtedly, a device using several diodes can be created relatively easily given the will, time, and money to do it, that results in a powerful handheld beam as ricktrent4 has done.

Click to expand...

Right. I think what the guys at Lockheed and MIT are trying to do is fundamentally different from what is necessary for this project to function at an effective 100w with a nice energy density. That being said, what ricktrent4 did was some knife edging, basically following this diagram exactly:




If it's difficult to get multiple diodes to collimate and form a single beam "in flight", why don't we forget about what the lasers do in flight and instead think about getting them to focus on a target at range? With a laser range finder, we could get very accurate distance readings out to 100m on even relatively non reflective targets (16 times per second). These range finders will output the distance measurement to whatever you want, so with an Arduino board, a little lens math, and a servo, we could recreate something similar to the autofocus function of digital cameras: moving the second lens to bring the 20 beams to bear on a single target no matter what (reasonable) range it's at.

Sigurthr said:

When it comes to diode lasers it is best to assume 20% efficiency when designing heatsinking for continuous use, i.e. if you want 200W out you need to remove 800W of heat. This alone makes the design you proposed unrealistic.

Click to expand...

I agree that a CO2 laser or something actually made for cutting/burning would be a better choice, but cooling one of those diode arrays isn't that unrealistic. Those laser projectors are already cooling off their high-powered arrays with just fans and heatsinks. Tripling that up would be about the same, and with peltiers and a bit of active cooling it should work out. It's certainly not going to light though.

You must spread some Reputation around before giving it to Encap again.

playludesc
Don't be surprised to see black vans zooming around your house soon :gun: Reminds me of a "Safety Not Guaranteed" movie. BTW, iirc the guy stole a laser from the lab :san:

As for the project, yes, it is possible. Though you must have a lot of free time and a lot of monies. You've seen similar stuff on the TV, aka youtube. Buy a farm field for your tests, otherwise be ready to deal with annoying people and police. Even better apply for the job in companies what already produce those lasers.

It's not a toy, be careful.

:lasergun:

Black vans? Usually black SUVs, guys wearing suits and dark glasses and always have something in their ear (Bluetooth?) they carry guns and have no sense of humor. One important warning: once you agree to talk to them, make no mistakes, everything you say must be true and don't leave out any material information or you are bantha fodder.

Alan

Pi R Squared said:

Black vans? Usually black SUVs

Click to expand...

yeah, right. White vans, black SUVs :wave:

If I were planning to pick up a guy suspected of possessing a high-powered laser, I would probably choose a vehicle painted in a color more reflective than black. Just saying...

Poodoo. Uhmm this conversation is making me uncomfortable. ....

Pi R Squared said:

This subject has come up here many times before and people never believe it, they always think with the right optics you can combine any number of beams but it isn't so.
Alan

Click to expand...

So true, they don't believe it.

As I mentioned earlier--everything is possible in imagination---not so in the real world.

I have been reading this thread, trying to think of a way to combine laser beams from diodes. Would using a fiber optic cable from each diode to channel the light from each diode to a lens shared by all fiber optic cables work? The three ways of combining lasers
( knife edge, PBS, dichro) seam to focus on combing the beams. My idea with the fiber optics is to combine the light, then make a beam out of it. Is this a reasonable idea?