Homing Laser

[avatarxprime]

With the various weapon research threads that have been popping up in recent weeks I thought I'd post this. Homing lasers (steerable beam weapons) are seen in various scifi as weapons that are usually quite a bit slower than lightspeed, but can lock-on to and track a target. They can't be real lasers thanks to their lack of speed and that fact that they bend, things like the Airy beam not withstanding. However, any idea I've seen offered up on how to make an energy weapon that has the visual style of a homing laser always ends up in the same vein as a plasma weapon with a "Why not skip the beam and use incredible effect x to attack your enemy directly?" Does anyone have ideas on producing a scifi style homing laser that is not made of compounded stupid or should I just abandon the idea?

[Stark]

You mean like the famously horrible omega beams used by Darksied to shoot himself over and over again when people lead them back to him? :V

[Ford Prefect]

It's not hard to assume that the mechanism which bends the beam simply isn't intense enough to cause damage directly. I mean, sure, if I can bend a laser in real life my control over spacetime indicates that I'm probably God, but there's a lot of shit in sci-fi which is readily accepted which is a whole lot more bizarre than the homing lasers in Zone of the Enders.

Ultimately you don't even need to know: I seriously doubt that any story will have any need to explain the mechanism behind its bendy lasers.

[Lord of the Abyss]

Hmmm. How about a thin (too thin to see easily at a distance, for the right visual effect) highly conductive powered cable that can be shot a great distance and made to flex for such things as going around corners. When it hits, a massive charge is discharged along the cable, turning it in effect into a directed lightning bolt. Not really a flexible beam but it'll look like one.

[JointStrikeFighter]

Missile with a blue light in the back like those ruski SACLOS missiles which use a light bulb

[Sea Skimmer]

Just have a beam director on the end of the laser weapon. That would be precisely how the Airborne Laser worked.

[Simon_Jester]

That's a very smart way to design a laser weapon, but it's not quite what's being discussed with this idea of beams that bend in mid-trajectory.

[Eleas]

That's a very smart way to design a laser weapon, but it's not quite what's being discussed with this idea of beams that bend in mid-trajectory.

To be outlandish for a moment, Greg Egan's novel Luminous featured an eponymous optical supercomputer. The conceit here was that Luminous featured not just lasers but some kind of laser-created standing-wave optical phenomenon that could in effect act as a mirror. In other words, the computer itself was entirely made out of lasers in a sealed, empty chamber.

[Sarevok]

Though the OP says laser a laser won't be very visible anyway. A charged particle beam on other could be be both visible and tend to arc.

[Batman]

Um-the OP already acknowledges they can't be real lasers, what with the not moving at lightspeed and all?
Then there's arcing, and there's Omega Beam style zigzagging. I don't know that's impossible with a particle beam, but you've got your work cut out for you and it's almost inevitably not worth the effort even if it's possible.

[Dwelf]

I don't think I've seen bending beam weapons in any setting that does not have pretty advanced technology. My candidates for bending the beam would be a weaponised varient of either the arificial gravity, the inertial dampners or the FTL drive. Assuming your target has similar technology it kind of makes sense that you cannot directly affect their ship with any of these. If you try to affect them directly their systems automatically cancel your attack out but if you guide something in externally you can try to fight them on the final approach even if you both cancel each other out since your attack has an extra component you're ahead. The same effect could give you those curved laser deflections that you sometimes see where the beam diverts around the target.

[Darth Wong]

I don't think I've seen bending beam weapons in any setting that does not have pretty advanced technology. My candidates for bending the beam would be a weaponised varient of either the arificial gravity, the inertial dampners or the FTL drive. Assuming your target has similar technology it kind of makes sense that you cannot directly affect their ship with any of these. If you try to affect them directly their systems automatically cancel your attack out but if you guide something in externally you can try to fight them on the final approach even if you both cancel each other out since your attack has an extra component you're ahead. The same effect could give you those curved laser deflections that you sometimes see where the beam diverts around the target.

This is a discussion of technology, not D&D magic spells. The fact that the other guy has the same technology doesn't mean the two would necessarily "cancel out". Honestly, this is just child-like reasoning. Do you reason that a tank gun is useless because the other tank also has gun technology?

[Dwelf]

Or maybe I thought that since artificial gravity or inertial dampning is being used in a manner that prevents humans from turing into red good when manouvering without completely borking up their system that there may be some level of fine control involved. FTL is pure magic so why the hell not.

[Darth Wong]

Or maybe I thought that since artificial gravity or inertial dampning is being used in a manner that prevents humans from turing into red good when manouvering without completely borking up their system that there may be some level of fine control involved. FTL is pure magic so why the hell not.

Don't be an idiot. Of course there's fine control involved. That does not mean you can arbitrarily say that they can accomplish anything they please.

[Dwelf]

Your thinking about this wrong it's not a I have a cannon you have a cannon well I guess they cancel each other out it's I have explosives you have explosives. You build a cannon I build reactive armour they cancel each other out at least for a time.

If we have artificial gravity we can generate acceleartion on an object from a distance.
If we have inertial dampners we can cancel out the effects of acceleration from a distance.
AG turns the beam and the inertial dampners prevent you using that same mechanic to tear my vessel apart.
I just don't see it being that much of a leap to cause and effect your way up from simple ship board AG and ID to having homing beam weapons.

[Batman]

If we have artificial gravity we can generate acceleartion on an object from a distance.

Because-you say so.

If we have inertial dampners we can cancel out the effects of acceleration from a distance.

Because-you say so.

AG turns the beam and the inertial dampners prevent you using that same mechanic to tear my vessel apart.

doesn't work and-because you say so.

I just don't see it being that much of a leap to cause and effect your way up from simple ship board AG and ID to having homing beam weapons.

That's because you're a moron. Why, exactly, does the ability to generate a 1g artificial gravity field across your ship, or compensating for acceleration pretty much up to infinity in any way affect your ability to manipulale the trajectory of your beam weapons?

[Dwelf]

If we have artificial gravity we can generate acceleartion on an object from a distance.

Because-you say so.

Not because I say so because it makes sense. Unless you put the generators on the crew members the acceleration is at a distance.

If we have inertial dampners we can cancel out the effects of acceleration from a distance.

Because-you say so.

Yep helpful but the OP never said that it was hard scifi just that it needed a reason why they were not using the effect directly as a weapon.

AG turns the beam and the inertial dampners prevent you using that same mechanic to tear my vessel apart.

doesn't work and-because you say so.

I just don't see it being that much of a leap to cause and effect your way up from simple ship board AG and ID to having homing beam weapons.

That's because you're a moron. Why, exactly, does the ability to generate a 1g artificial gravity field across your ship, or compensating for acceleration pretty much up to infinity in any way affect your ability to manipulale the trajectory of your beam weapons?

Why do the scientists have to stop researching artificial gravity when they reach a stable 1g field? It seems like a good field for weapons research. If you can manage to generate the field outside a closed environment and dial the output up you have the makings of a weapon. Sure you can brute force combat by bringing more powerful or numerous gravity weapons but once they exist people start working on a counter for it. Its perfectly possible that the counter does not have the range of the weapon but changes the balance so it's more practical to move back to normal weapons. At this point you have the ability to accelerate objects outside the vessel if the power requirement of redirecting a beam is lower than what is required to fire a new one if it would miss then why the hell would you not do it.

[Formless]

Dwelf, even if your logic holds-- which it does not-- then you can just as easily nullify an anti-grav based or inertial dampening based homing beam attack. QED, you are an idiot.

And moreover the reason you logic sucks? If you could generate enough force with these technologies to cause damage to a ship you would use them to throw around good old fashioned bullets, not fricken homing lasers. And this isn't even getting into the absurdity of ignoring the laws of motion at a whim, which pretty much discredits your idea that these things can "cancel each other out" unless it really is D&D magic.

[Darth Wong]

Your thinking about this wrong it's not a I have a cannon you have a cannon well I guess they cancel each other out it's I have explosives you have explosives. You build a cannon I build reactive armour they cancel each other out at least for a time.

No, they don't "cancel each other out". People didn't declare that tank guns were useless when reactive armour came along.

If we have artificial gravity we can generate acceleartion on an object from a distance.
If we have inertial dampners we can cancel out the effects of acceleration from a distance.
AG turns the beam and the inertial dampners prevent you using that same mechanic to tear my vessel apart.
I just don't see it being that much of a leap to cause and effect your way up from simple ship board AG and ID to having homing beam weapons.

Let me guess: you've never designed anything more complex than breakfast.

At what range do these effects work? What is the rise time? What is the settle time? What is the delay between detection of the effect and initation of your own countermeasures? How can you possibly detect the effect at all before it is already damaging your vessel? If you cannot detect it before it begins to interact with your vessel, how can you use your own systems to "cancel" it, even if we accept all of your other assumptions? This is just one concern with your mindlessly simplistic attitude. As I said, I'd be willing to bet that you don't know technology from tacos, and you've never designed anything more complex than breakfast.

[Formless]

As to the OP, here is the question I think ought to really be asked: what purpose does this weapon serve? Remember, in theory the real advantages of raygun style weapons is that they have reduced ammo concerns, and (if we're being realistic) they should reach their target faster than a projectile or missile. However, zigzagging and whirling around like a missile adds to the distance the beam has to travel, increasing the time it takes to reach the target and presumably whatever energy wastage the beam would have.

The one application I can think of where it would be useful is if you want to strike a target that you lack a straight line of sight to. This problem will mostly be found in planetary environments, but there are times where it will occur in space as well. Lets imagine you want to shoot someone on the opposite side of Yavin. Your options are:

1. Wait for the target to come into view naturally. This could take a while, depending on the orbital period of both you and the target.
2. Force the target into line of sight by moving your ship to engage. This uses fuel, and assuming the target is armed and using tactic #1 the situation will devolve into an elaborate quick draw contest. With spaceships.
3. Blast through the obstacle. Good luck. This isn't so much a viable tactic when fighting around a planet as when fighting around smaller objects such as asteroids, comets, debris fields, planetary ring systems, protoplanetary disks, or if you are trying to hit a specific ship in the middle of a tight formation.
4. Fire some type of homing weapon like a missile... or homing raygun. Missiles might have advantages like better ability to lock on target, whereas a homing raygun (even a relatively realistic option like a physical beam director that deflects a laser towards the target) might be harder for the target to shoot down with point defenses. Precisely what these advantages or tradeoffs will be will depend on how the homing raygun works, of course.

Even if you are going for a soft sci-fi visual feast and don't care if it works on technomagic knowing why this weapon is being used over more obvious ones will help you keep it from feeling generic or self serving, and will reveal ways to work it and other weapons into a battle scene that keep the reader/viewer interested.

[Lord of the Abyss]

Another possibility; whatever the beam is made of is attracted to the target, like lightning to a tall or charged object. Attracted to whatever exotic matter a ship uses for its FTL drives, say. This also provides a good reason to favor these beam weapons over something more ordinary; a beam that is sucked towards its target has obvious advantages.

[avatarxprime]

Wow, I have to admit this got more discussion than I thought it would. Just want to say thanks to everyone who posted.

Ultimately you don't even need to know: I seriously doubt that any story will have any need to explain the mechanism behind its bendy lasers.

I agree that the story wouldn't turn on why the beams are capable of homing in on a target, but the handwaving involved can introduce concepts that can go on to have issues for the story in the "if you can do that, why can't you do this" vein.

Hmmm. How about a thin (too thin to see easily at a distance, for the right visual effect) highly conductive powered cable that can be shot a great distance and made to flex for such things as going around corners. When it hits, a massive charge is discharged along the cable, turning it in effect into a directed lightning bolt. Not really a flexible beam but it'll look like one.

Yeah I thought about someting like that, but unless you're fighting at proverbial knife-fighting range it would get all kinds of ridiculous.

Just have a beam director on the end of the laser weapon. That would be precisely how the Airborne Laser worked.

Like Simon_Jester pointed out, that's not quite what I had in mind. Besides, if I'm going down that route why don't I go for broke and assume the civilization in question developed phased array lasers? It certainly has a nice scifi feel to it. Besides, with phased array optics integrated throughout the ship I can get extra benefits out of it too.

As to the OP, here is the question I think ought to really be asked: what purpose does this weapon serve? Remember, in theory the real advantages of raygun style weapons is that they have reduced ammo concerns, and (if we're being realistic) they should reach their target faster than a projectile or missile. However, zigzagging and whirling around like a missile adds to the distance the beam has to travel, increasing the time it takes to reach the target and presumably whatever energy wastage the beam would have.*snip*

Yeah, obviously this technology would slot nicely into laser artillery that can fire over the horizon (honestly AT-TEs got me really thinking about this again) and that is one thing I have in mind for it. As to regular combat, I was thinking it would function as a beam weapon that can be fired at fast moving targets and actually alter its trajectory to insure hits. Essentially it's trying to combine the benefits of guided projectiles and beam weapons for the cost of more reactor power. However, for an interstellar Space Opera scifi civilization the increased power requirements aren't that big a deal. All that being said, I admit it's mostly a stylistic choice and I would have regular beams, missiles and other weaponry being used as well.

[Simon_Jester]

As long as you accept that the science fiction you're looking at is quite, quite soft, fine.

Physically there's no explanation for how a 'beam' of light, or of other waves analogous to light, or of fast moving particles, could be made to bend or zig-zag the way you describe. Nor is it easy to think of applications other than shooting around corners- if you're fighting the enemy from far enough away that dodging a laser is practical for them, you're fighting from far enough away that you can't get up to the second observations of them to adjust the direction your beam is traveling.

But again, as long as you accept that this is very soft (runny?) SF, you may be able to build good story around it.

[Ford Prefect]

I agree that the story wouldn't turn on why the beams are capable of homing in on a target, but the handwaving involved can introduce concepts that can go on to have issues for the story in the "if you can do that, why can't you do this" vein.

That's not an issue. Ultimately you are the final arbiter of what can and cannot be done in anything you write. If someone asks 'why don't you do xyz thing with abc technology' you can quite simply say 'because that is outside the scope of the application of this technology'.

[Sea Skimmer]

That's a very smart way to design a laser weapon, but it's not quite what's being discussed with this idea of beams that bend in mid-trajectory.

All right, I didn't get that, nor does it make any sense. Even a .01 C is still what, about 3 million meters per second. Really hard to hit someone at that speed. You could still attack a target in orbit of the moon with little more time lag then was required for a maximum range salvo from battleship guns making beam bending rather unimportant. Looking at the rest of the thread this is really more fantasy.