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One issue with a laser sword (light saber) is stopping the light beam at a desired length, There have different designs to re-create a similar effect using lasers and plasma, usually with some sort of internal coil or a bar running the length of the sword.

The idea I have in mind will work best with lasers and to stop the laser will be a drone at the tip of the sword acting as the mirror to reflect the laser back and give it length. The drone can use the laser to lock onto its position and even use some of the energy to power itself. It would limit the strikes to only along the length of blade and not the tip.

Is this possible that a drone could be used as the reflector end of the light sword?

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    $\begingroup$ The modern interpretation of a lightsaber is actually a plasma sword bound within a magnetic field. And you're better just using it as a laser gun if you can project a laser beam. $\endgroup$ – Halfthawed Jun 16 '20 at 14:48
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    $\begingroup$ This is a clever idea, but the drone becomes the weakest part of the sword. Destroy the drone - destroy the sword. Any manufacturing that makes the drone impervious begs the question "why not make the whole sword out of that stuff?" Could a drone reflector work? Sure. Does it make logical sense? Sure. Is it practical? Maybe not. $\endgroup$ – JBH Jun 16 '20 at 15:23
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    $\begingroup$ Why bother reflecting the energy, instead of just absorbing it? It's unclear why you'd want to reflect the beam back to the hilt, when you could just have an opaque object at the desired length to stop the beam. As it is now, the hilt must be designed to both emit and absorb the energy beam, but you could easily separate those two and never have to point a potentially dangerous beam at yourself.. $\endgroup$ – Nuclear Hoagie Jun 16 '20 at 15:54
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    $\begingroup$ Why sword? your laser is going through everything including another "laser sword" but nice thinking! ;D $\endgroup$ – user6760 Jun 16 '20 at 16:00
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    $\begingroup$ Now that I think about it, using this idea for a set of Nunchaku might be cool beyond belief - especially if you could keksi a way to add some elasticity to the light so the other end of the Nunchaku would swing out and around the neck of your foe. Hah! Then you could look philosophical about it, like Bruce Lee, and your opponent would have died with honor. $\endgroup$ – JBH Jun 16 '20 at 17:47
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Frame challenge: instead of reflecting the beam back to the hilt with a technologically complex drone, just use an opaque beam absorber that's affixed to the hilt.

As other answers have pointed out, reflecting the beam back toward the user adds unneeded risk - if the reflector gets misaligned even a little, the user could accidentally chop their own hand off. Additionally, the beam emitter now has to perform double duty as a beam absorber, adding complexity to the apparatus. If all you need to do is halt the beam, you just need an beam absorber instead of a beam reflector.

A drone is also a rather complex and fragile way to keep the reflector/absorber in the correct position. It would be far simpler and more reliable to just attach the reflector/absorber at the end of a blade-length arm which is affixed to the hilt (sort of like a selfie stick). This would mean the sabre is no longer omni-directrional, as you must swing the blade with the arm in the back. This shouldn't be a huge issue, though, since I can't think of any regular sword that allows you to cut in any direction. If you really need to swing the sword in any possible direction, some control electronics could be implemented to rotate the arm away from the direction the sword is swung, ensuring that the blade rather than the arm hits the target first. This rotation mechanism will be far simpler than the control electronics needed to keep a drone hovering at a precise spot in 3D space.

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  • $\begingroup$ I was trying to avoid the selfie stick (lol) method by cutting out the stick with the drone but thats a nice solution having the arm rotate away, I still like the absorbing drones also. $\endgroup$ – user69935 Jun 16 '20 at 20:48
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    $\begingroup$ It doesn't have to be directionally limited. The stick could run along the centre of the beam. The beam would create a large gap that the stick could easily pass through. $\endgroup$ – chasly - supports Monica Jun 16 '20 at 23:21
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    $\begingroup$ @RandySavage How the drone knows where is the user going to swing the blade to? The tip of the blade can reach speeds of an appreciable fraction of the speed of sound. A drone would have to accelerate at several G's in any possible direction, and, what is way worse, being able to stop at several hundred G's or it will be missaligned with the hilt. Since the drone can't know where are you going to strike until you start moving the hilt it is always going to be behind the beam. $\endgroup$ – Rekesoft Jun 17 '20 at 7:18
  • $\begingroup$ @Rekesoft thats true, tbh I have them more in mind for the odd decapitation rather than long drawn out fights, so that could help with the believability for the odd single strike. and I could say its alignment is so intuitive and precise it the drone can react in spilt seconds to realign. $\endgroup$ – user69935 Jun 17 '20 at 11:28
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I want my light saber energy going away from me.

The problem with reflectors is that they turn energy going away from me into energy going towards me. I do not want that energy back over here. If the drone reflects it perfectly it will go back into my lightsaber doohickey and then what? All the stuff in that thing is meant to emit energy. Now I also have to have something in there that absorbs energy? It already hangs down from my belt in an awkward way and now it will have to be bigger. People will think I am trying to compensate. Plus if I run it will bounce uncomfortably, and I might run.

Worse is when I get excited, or something jostles the drone. Now when it reflects it misses the doohickey and hits my lightsabering hand and there go the knuckles. I will need a reflective glove. Or it misses doohickey and hand entirely and hits my pants or my foot or my Ewok sidekick.

Nay; nay - we will leave the drone for use during welding mask-wearing Force using saber sessions. We will keep the saber svelte and Ewoks and Jedi pants safe.

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  • $\begingroup$ How about if the laser is reflected back to have a wider radius that it hits a reflector around the laser, like a fencing hand guard? $\endgroup$ – user69935 Jun 16 '20 at 15:00
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    $\begingroup$ You're still bouncing back lethal energy at yourself, which is an odd thing to want to do. No mirror is perfect and the drone would heat up given time and lose its effectiveness, causing more heating and even worse reflectivity until it exploded or had to disengage. If you need to shine a laser at a drone, you'd be better off using the drone to reflect beams around corners at the actual target in short bursts. $\endgroup$ – abestrange Jun 16 '20 at 15:29
  • $\begingroup$ Worth doing if the light goes back into the gain medium of the laser. That way the return energy of your beam saturates the laser, so you won’t end up wasting more energy than you strictly need to (if I’m remembering my laser physics right), which is important if you have a limited power supply. It’s still a stupid idea though. One tiny misalignment and poof goes the wielder. $\endgroup$ – Joe Bloggs Jun 16 '20 at 18:29
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You have two main issues: if you are using a sword, you want to swing it around and maybe even point it to your target.

  1. Swinging it around: due to the geometry of the sword, the tip will be always moving around faster than your hand. This means that the drone will have to chase your hand movements quickly and precisely, no matter how they are. Else if you lose it you lose your blade.
  2. Hitting your target with the tip of the blade: obviously if you do this, you want the point to penetrate your target. But the point in this case is the drone. If the drone is passive from this point of view it's like hitting your target with a retractable blade: good for a Hollywood movie, not for a real fight. If instead the drone is active and can go through your target, why are you bothering having a laser when you have piercing drones?

Moreover your drone is the weak spot of your blade: as soon as your target can incapacitate or disturb it, you are left with no sword.

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