long range laser

Michael Everett wrote:This sounds alot like the Sunbeam concept from the Lensman series. You use a large number of gravitational lenses to reflect, refract and focus a large pergentage of the star's output along a single vector. The result is not actually a laser, but is a photonic beam of such strength that at the very least, it would cause normal matter to simply sublime, or evaporate. The only problem is getting the beam to hit the evading target, you'd need to cause the incoming hostiles to utilise a predictable path and not "hide" behind things like planets and so forth.

Yaay! We're having another "Lensman Arms Race"!

Awaiting comments.

unfortunately, the ships would just need to move a little to get out of the way of a direct fire laser if its fired at long range. that is why there is the second mirror. the mirror is to redirect the laser at veryshort range so that its accurate, and it is powerful enough that just one could do enough to mission kill a DN.

Since these platforms have a separate power source for the weapon, it can be small and very hard to detect so it won't be destroyed until its very close.

There are two reasons lasers are ineffective against sidewalls at greater than half a million clicks.

One is just that the sidewall's ability to bend light seems to get a lot more effective with range from the emitter. This is why "knife range" improves penetration of a shrike attack, why relatively weak laser-head beams punch through sidewalls at 30km that require hugely powerful beam weapons at 300km to get to the armor.

I don't know why that is, but sidewall effects are magic, they work however David says they do. It doesn't seem to matter how powerful your beam weapon is, at greater than 2 light seconds, it does squat against even a relatively weak sidewall. This might actually be a targeting problem to some extent, it is hard to tell.

The second issue is targeting. The wedge messes up sensors and you don't really know where in the giant wedge the relatively tiny ship actually resides. Close range FTL sensors would help with that quite a bit, but they don't solve the problem of the ship moving a large distance between the time the beam fires and the time it arrives on the scene. Ships that accelerate at multiple hundred G's can shift position a lot in even a couple seconds.

I don't think it is as simple as having a retargeting "mirror" (I assume some kind of gravitic lens) to shift the beam at the target. That means you are really shooting at the sensor, accurately enough to hit the grav lens (and not splash the sensor), and that the lens itself can very precisely aim an incoming beam from any angle to any other angle.

solbergb wrote:.....snip....

I don't think it is as simple as having a retargeting "mirror" (I assume some kind of gravitic lens) to shift the beam at the target. That means you are really shooting at the sensor, accurately enough to hit the grav lens (and not splash the sensor), and that the lens itself can very precisely aim an incoming beam from any angle to any other angle.

I believe that if a missile with limited computing power, traveling at half the speed of light, requiring less then 1/100th of a second to compute 5 or 6 different lasers to hit a target with reasonable accuracy, means a station sized cannon with station sized computers and plenty of time,can hit a platform that isn't even moving just fine at long range. (whew i think i need to chop that sentence up.)


Not to mention the that you can launch KE strikes from out of system with reasonable accuracy to hit a station. (its why they are so vulnerable) it would be even simpler with shorter ranges.

it is also dead simple to calculate where the laser will go when you reflect it. its simple reflection. we do it now all the time.

I'm not sure we do it today when the target is both moving at high accel and is fuzzed by a sidewall, where the sensor environment includes EW and EMP and sudden death of sensor if the sensor is detected (if you're close enough to eliminate lightspeed lag, you're close enough to be in energy range of the target) and when both the sensor mirror and the computing platform are moving independent of each other.

I'm just saying it is probably more difficult than you think.

solbergb wrote:There are two reasons lasers are ineffective against sidewalls at greater than half a million clicks.

One is just that the sidewall's ability to bend light seems to get a lot more effective with range from the emitter. This is why "knife range" improves penetration of a shrike attack, why relatively weak laser-head beams punch through sidewalls at 30km that require hugely powerful beam weapons at 300km to get to the armor.

I don't know why that is, but sidewall effects are magic, they work however David says they do. It doesn't seem to matter how powerful your beam weapon is, at greater than 2 light seconds, it does squat against even a relatively weak sidewall. This might actually be a targeting problem to some extent, it is hard to tell.

The second issue is targeting. The wedge messes up sensors and you don't really know where in the giant wedge the relatively tiny ship actually resides. Close range FTL sensors would help with that quite a bit, but they don't solve the problem of the ship moving a large distance between the time the beam fires and the time it arrives on the scene. Ships that accelerate at multiple hundred G's can shift position a lot in even a couple seconds.

I don't think it is as simple as having a retargeting "mirror" (I assume some kind of gravitic lens) to shift the beam at the target. That means you are really shooting at the sensor, accurately enough to hit the grav lens (and not splash the sensor), and that the lens itself can very precisely aim an incoming beam from any angle to any other angle.

Part of an energy weapons ineffectivness has to do with the fact that when you double the distance from a light source the intensity of that light is quartered and 2 light seconds is a HUGE distance. The moon is less than 2 light seconds from Earth. I'm not sure how that effects lasers but I'm sure like a light bulb the intensity does reduce as a factor of distance so that the sidewalls have less energy to deflect.

I think that the ability of a sidewall to blunt beam weapons attacks might be less mysterious than we think. First and foremost, the sidewall might multiply the divergence angle of the incoming beam. Given the hints that we have from Weber combined with known physics, the diverence angle of a Graser will be much smaller than of a laser so Grasers would be better at penatrating Sidewalls then lasers. However; Weber also alludes to the difficulty of "focusing a hot emitter" in the graser system which suggests that the optical performance of Grasers falls far short of diffraction limitation. Finally; the fact that very large yield warheads mounted on SKMs were once used to "burn out" sidewalls suggests that there is a maximum energy threshold above which a sidewall ceases to be effective.

A Phased Array Graser would have a much lower divergence angle than a normal graser, laser or X-ray laser that a sidewall could multiply. The energy density would also be hellishly intense, exceeding the gigaton yield sidewall burners that had once been in use.

Now keep in mind that I'm not arguing that the above is the way things are or the way things out to be. I'm simply suggesting that this might be the way things are in Weber's Honorverse or the way things reasonably could be if Weber decides to tweak the rules of the Honorverse a bit. I wouldn't consider this to be a Deux Machina (someone wil nail me on the spelling) abuse that often times motivates me to throw an offending book across the room.

Keep in mind that Phased Array Graser technology is probably a low mass penalty modification of any ship that has a multiple graser armament. You will also note that all of the SD(P)s as well as the BC(P)s, NIKE BC(L)s, SAGANAMI Cs and ROLLAND DDs have all Grasers rather than the traditional mixed Graser/Laser energy armament in their broadside and chase armament. You will also note that that the key components that would destinguish a Phased Array Graser from a normal Graser installation would be a central, low power Gamma Ray Laser oscillator, beam splitter, wave guides (or just evacuated channels), and phase shifter arrays mounted on the breach end of the main Graser mounts. (yes, I know that we don't know how to build Graser mirrors and lens or Graser waveguides or Graser phase shifters, but I'm assuming that Honorverse Tech can) All of this would be rather unobtrusive so that it would seem reasonable that most crew didn't notice the sytems, or understand what they were, and the officers in the know wouldn't talk about them in normal conversation. Also, these systems are something that Manticore might be able to produce and retrofit with the limited manufacturing capacity that survived Oyster Bay.

The end result here is that Phased Array Graser / Long Range Laser technology might be a force multiplier which would allow Manticoran ships to engage and defeat SLN as well as other ships without having to deplete the finite supply of SKMs that presumably will be needed to defeat the Mesan fleet.

solbergb wrote:There are two reasons lasers are ineffective against sidewalls at greater than half a million clicks.

One is just that the sidewall's ability to bend light seems to get a lot more effective with range from the emitter. This is why "knife range" improves penetration of a shrike attack, why relatively weak laser-head beams punch through sidewalls at 30km that require hugely powerful beam weapons at 300km to get to the armor.

I don't know why that is, but sidewall effects are magic, they work however David says they do. It doesn't seem to matter how powerful your beam weapon is, at greater than 2 light seconds, it does squat against even a relatively weak sidewall. This might actually be a targeting problem to some extent, it is hard to tell.

The second issue is targeting. The wedge messes up sensors and you don't really know where in the giant wedge the relatively tiny ship actually resides. Close range FTL sensors would help with that quite a bit, but they don't solve the problem of the ship moving a large distance between the time the beam fires and the time it arrives on the scene. Ships that accelerate at multiple hundred G's can shift position a lot in even a couple seconds.

I don't think it is as simple as having a retargeting "mirror" (I assume some kind of gravitic lens) to shift the beam at the target. That means you are really shooting at the sensor, accurately enough to hit the grav lens (and not splash the sensor), and that the lens itself can very precisely aim an incoming beam from any angle to any other angle.

It seems to me that since you would not know ahead of time where your mirror would be relative to the target and the emmitter, that each mirror would need to be able to change not only its position and orientation but also its shape very rapidly, maybe several or many times a second. At this level of complxety, I would expect things to go wrong on a regular basis. Remember Murphy's Law

This is why you don't bother with a forward deployed mirror. All you need is a recon drone to give you updated targeting info using FTL comm. This will not give you the ability to engage manauvering starships at ranges measured in Light Minutes. However; the reduced divergence angle and higher power density of a phased array radar combined with a recon drone providing targeting data via FTL comm might extend the potentially effective engagement range by a factor of 10 to about 1 to perhaps even 3 million kilometers. The major limiting factor would be the random component of the target's accelleration. As I posted earlier, there might be limitations on the rate that the wedge strength can be increased and decreased and slew rates for the various types are also not instantaneous. If the random component of accelleration is limited to 100 gees then the potential dodge distance is

1/2 x 1,000m/s^2 x (3 LS)^2 = 5,000 meters.

This is less than an order of magnitude larger than the dimensions of the ships. Scoring a hit with mulitple shots should be possible.

Then of course there is the lesson of the USS INDIANAPOLIS whose Captian decided to not zigzag after delivering the Atomic Bomb and got torpedoed. Until oppponents realize you have ultra long range grasers, they aren't going to be manauvering evasivlely.

catfish wrote:It seems to me that since you would not know ahead of time where your mirror would be relative to the target and the emmitter, that each mirror would need to be able to change not only its position and orientation but also its shape very rapidly, maybe several or many times a second. At this level of complxety, I would expect things to go wrong on a regular basis. Remember Murphy's Law

The function of the mirror isn't targeting. It is to concentrate the laser and compensate for dispersion. I doubt that a mirror would be able to withstand the laser, unless it was coated with handwavium.

Sheriff Yoda wrote:Part of an energy weapons ineffectivness has to do with the fact that when you double the distance from a light source the intensity of that light is quartered and 2 light seconds is a HUGE distance. The moon is less than 2 light seconds from Earth. I'm not sure how that effects lasers but I'm sure like a light bulb the intensity does reduce as a factor of distance so that the sidewalls have less energy to deflect.

The inverse square law only applies to non-coherent point sources, so lasers don't behave that way. A Gaussian laser beam expansion is based on the square of the radius of the beam divided by wavelength. Look up Rayleigh length.

Which is why DW should have never introduced huge gamma ray lasers as standard armament, they maintain the ability to do damage to seemingly totally absurd distances, as in light hours to light weeks.