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The Expanse and its compatibility with OA
(05-19-2019, 04:00 PM)The Astronomer Wrote: On lasers: even if we can't build bigger ones, we can always shove many of these smaller ones together. Is there is any reason a big laser would be less efficient than smaller ones?


Quote:In the end, the primary way to combat thermal lensing is with cooling. And the primary way to cool your laser is to make it bigger.
If the proportions of a laser are kept identical, lasers can be scaled up or down with minimal change to the laser’s efficiency or output power. Indeed, you can pump 100 MW or power into a tiny palm-sized laser just as well as you can into a building-sized laser, and they will produce roughly equal beams in terms of efficiency and [Image: latex.php?latex=M%5E2&bg=ffffff&fg=000000&s=0]. The only difference is that the palm-sized laser will melt into slag when you try to fire it.
Laser size is mostly a matter of how much do you need to distribute the heat of the laser pumping. And if you want to combat thermal lensing, you’ll want a really big laser. This means laser size is essentially about cooling, and by extension, having a low [Image: latex.php?latex=M%5E2&bg=ffffff&fg=000000&s=0].
And because size is closely related to mass, and mass is so critical to spacecraft design, the limiting factor of using lasers in space is how poor of an [Image: latex.php?latex=M%5E2&bg=ffffff&fg=000000&s=0] you want to have, given a certain power level. Though the radiator mass needed for the enormous power supplies is the other major consideration.


Quote:A final way to combat thermal lensing is to use Beam Combining of many smaller lasers. Combining beams side by side increases the beam waist linearly, which defeats the point, but Filled Aperture Techniques can combine beams without increasing the beam waist. However, this technique produces greater inefficiency to the final beam. The ideal way to combine beams is to simply use multiple separate lasers which all focus on a single point.
So yes, if you can prevent the mini-lasers from melting under their own energy, and solve a non trivial aiming problem? Then you can have "laser banks".

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RE: The Expanse and its compatibility with OA - by Noclevername - 05-19-2019, 04:17 PM

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