|
|
Post by EshaNas on Dec 26, 2017 19:29:55 GMT
Apparently, we've broken through and gone from phased radio arrays to phased optics, which DARPA is apparently researching via EXCALIBUR to form lasers. They claim that it'll be 10 times lighter and efficient than common mirror-laser weapons. What does this bode for space warfare? Space-borne lasers suffer from inefficiency, massive amounts of waste heat and possibly other problems such as sheer mirror size to get any good range. Do Phased array optics change anything regarding that? This article from 2014 gives some rough numbers such as 35% efficiency for 100 KW, but notes that cooling is still a challenge - in an atmosphere, even! |
|
|
|
Post by Kerr on Dec 26, 2017 21:25:02 GMT
Apparently, we've broken through and gone from phased radio arrays to phased optics, which DARPA is apparently researching via EXCALIBUR to form lasers. They claim that it'll be 10 times lighter and efficient than common mirror-laser weapons. What does this bode for space warfare? Space-borne lasers suffer from inefficiency, massive amounts of waste heat and possibly other problems such as sheer mirror size to get any good range. Do Phased array optics change anything regarding that? This article from 2014 gives some rough numbers such as 35% efficiency for 100 KW, but notes that cooling is still a challenge - in an atmosphere, even! The claim is somewhat meaningless because we don't know which lasers they, if optimistic you can say they mean the Third Gen Laser system from General Atomics that achieve whooping 0.25kW/kg. This would mean 2.5kW/kg, if they just mean the average solid-state laser the actual value can be 1-0.5kW/kg. For comparsion Apophys 100MW physics breaker achieves 11kW/kg for the beam generator. And 2.15kW/kg with turret. Inefficiency: Modern military lasers are actually an magnitude more efficient than CDE Lasers, achieving 40% Wall-plug. Waste heat: As an result of higher efficiency less waste heat is produced but! These lasers operate at mostly "warm" temperatures. 400-500K, radiative power is equal to temperature to the power of 4. So an this laser might require 39x more area per radiated watt. Also because of higher effciency less powerful reactors are required. The total increase of radiator mass would be 20x. Range: Using an phased array replaces the mirror of an Laser, it also replaces the turret! An phased array can electronically steer the beam, instantly and with extreme precission. If it is really 10x then this would also help with mirror size. As 100% of your laser mass goes quasi into the mirror. What is more intersting is, what wavelenght did the phased array laser have @ferdiland? Cooling can be down in space via flowing hydrogen or some other gas over your laser, or behind them. The beam shouldn't be affected much. |
|
|
|
Post by n2maniac on Dec 27, 2017 22:20:56 GMT
IRL lenses and mirrors scale poorly with size with respect to mass, turn rate, cost, etc. I don't think we feel that too hard in CDE, do we?
Yea, the phased array can do some steering, but the individual lasers will need to steer as well if the adjustment is any larger than their diffraction-limited spot sizes.
A really interesting aspect is hardiness: lose a few elements of a phased array, and it still works (with reduced performance, assuming the guts that keep phase in sync are not destroyed).
|
|
|
|
Post by matterbeam on Dec 27, 2017 22:42:02 GMT
This is not really a phased array - it's a bunch of lasers taped together so that their beams can converge on the same spot. A phased array uses constructive/destructive interference between the laser beam wavelengths to focus the beam, which requires micrometer-nanometer sized emitters. Totally not what is happening here!  |
|
|
|
Post by n2maniac on Dec 28, 2017 0:26:54 GMT
They may actually be adjusting the phase of them relative to each other to increase the effective aperture size. The otherwise "large" spot size from the "small" lenses will have a constructively interfered bright spot if done correctly, and such bright spot can be steered around the larger spot by changing the phase. Again, still requires mirrors to steer.
|
|
elukka
Junior Member
Posts: 73 
|
Post by elukka on Dec 30, 2017 22:32:11 GMT
This is not really a phased array - it's a bunch of lasers taped together so that their beams can converge on the same spot. A phased array uses constructive/destructive interference between the laser beam wavelengths to focus the beam, which requires micrometer-nanometer sized emitters. Totally not what is happening here! This is something that has confused me. I've seen "phased array laser" being used to refer both to these hypothetical devices with nanonscale emitters and to arrays of conventional mirrors acting together to emulate a larger mirror. |
|
|
|
Post by Kerr on Dec 31, 2017 0:43:48 GMT
This is not really a phased array - it's a bunch of lasers taped together so that their beams can converge on the same spot. A phased array uses constructive/destructive interference between the laser beam wavelengths to focus the beam, which requires micrometer-nanometer sized emitters. Totally not what is happening here! This is something that has confused me. I've seen "phased array laser" being used to refer both to these hypothetical devices with nanonscale emitters and to arrays of conventional mirrors acting together to emulate a larger mirror. Did they used radar/microwaves in that context? Maybe they just shined all the individuals beam at one spot, uncohherent beam combining |
|
|
|
Post by goduranus on Dec 31, 2017 2:56:27 GMT
I always thought Phaser = Phased Array Laser, especially seeing how it was fired out of an array that didn't move while aiming. Until they came up with some other nonsense.
But what's this? I looked on wiki and it now says "phased array energy projectile" Looks like they retconned it to make sense again.
|
|
|
|
Post by Kerr on Jan 1, 2018 16:26:44 GMT
I always thought Phaser = Phased Array Laser, especially seeing how it was fired out of an array that didn't move while aiming. Until they came up with some other nonsense. But what's this? I looked on wiki and it now says "phased array energy projectile" Looks like they retconned it to make sense again. Did they atleast removed the "vaporization" stuff nowadays? I am fine with some kind of electrolaser |
|
|
|
Post by Kerr on Jan 19, 2018 14:09:49 GMT
EshaNas So I found what it really is, it isn't a phased array just like MB said, it is a phase-locked fiber laser array www.optonicus.com/conformal_optical_systems/It uses the phase-locking method to combine the beams of the individual subaperatures, this creates a laser beam which has the same focus a solid mirror or lens of the same size. It can't steer it's beam like a normal phased array, but it can move it's individual apertures. So it can create the effect that it can tip of tilt it's beam by e.g extending the lower aperates and retracting the upper ones. So it uses adaptive optics and phase locking to produce a quasi phased array with very little emitters and increased tracking speeds.
|
|
