Laser warfare in the sky...

Discussion in 'Off-Topic' started by cmartinez, Sep 21, 2015.

  1. cmartinez

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  2. alfacliff

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    whyy cant it be focused tightly? a coherent beam dosnt spread much. and the airborn laser project by boeing ran a lot more than that with adaptive optics to keep it on target regardless of atmospheric distortion.
     
  3. cmartinez

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    Because of the limits imposed in power density on the focusing lenses. That's because no lens is 100% transparent to any laser frequency. Say, if you had a lens with a 95% efficiency, then the remaining 5% turns into heat, cracking the lens. That's why they're usually cooled using a ring around its perimeter through which liquid coolant is being pumped. But that means that there will be a temperature gradient in the lens, since heat will be traveling from the center to its perimeter. And that gradient can only be so steep before the lens gives in and cracks.
    I think they must be focusing the laser from the resonator and into the target, probably achieving said 2-3 nanometers in diameter at the target... I very much doubt they have actually colimated the laser to such a small diameter.
     
  4. BR-549

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    I’m no expert, but I’m with you, from what I’ve read, that size of beam would be new.
     
  5. Wendy

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    Mar 24, 2008
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    I suspect it is a typo myself, that diameter is just not real.

    Even a 100mW laser could do real damage to a person at that diameter.

    The atmosphere also tends to have a defocusing effect too.
     
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  6. alfacliff

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    thats why the adaptive optics. at at the megawatt level, even a one meter beam diameter is good enough. for a 30 kw laser, why would any nanometer diameter beam be needed? especially when shooting down drones. our 1 to 1.5 kw lasers here used for cutting and drilling must focus down to concentrate the beam, but that also is to control the size of the cut and angles of the sides of the cut.
     
  7. wayneh

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    I suspect 'nanometers' was referring to the wavelength - in the x-ray range - and not the beam width. Journalists don't do well with physics.
     
  8. JoeJester

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    Are you suggesting the journalist "misquoted" and "misunderstood" what was being stated?

    Oh yeah, I forgot, one has to be quoted by the press to be misquoted by the press.
     
    Last edited: Sep 21, 2015
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  9. cmartinez

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    x-ray range? My bet would've been more on the infrared CO2 type of laser.
     
  10. cmartinez

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    My point exactly, that sort of laser that you're mentioning, has an output at its resonator of about 12 to 9mm diam, and then it's focused on the piece to be cut. That's why those pieces end up with an angle at its edges, and are not perfectly squared.
     
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