Lasers, Mirrors, and Visual Stealth Technology

Discussion in 'Physics & Math' started by Prince_James, Nov 9, 2006.

  1. Prince_James Plutarch (Mickey's Dog) Registered Senior Member

    Messages:
    9,214
    Does the reflectivity of a mirrored surface impact its ability to withstand high powered lasers without melting? For instance, would a mirror which reflects 99 percent of the light that impacts its surface be less likely to melt than one which only reflected back, say, 75 percent? Or can a mirror of any decent reflectivity prevent this?

    Similarly, would a laser have no effect on the up and coming "invisibility cloaks" which are being developed by scientists to redirect light around an object so that it appears invisible?
     
  2. Google AdSense Guest Advertisement



    to hide all adverts.
  3. Prince_James Plutarch (Mickey's Dog) Registered Senior Member

    Messages:
    9,214
    No one has any insight on this?
     
  4. Google AdSense Guest Advertisement



    to hide all adverts.
  5. Pete It's not rocket surgery Registered Senior Member

    Messages:
    10,167
    Yes. Incident light is either reflected, scattered, or absorbed. The absorbed light is what heats the object. The less that is absorbed, the less the object heats up.

    If light in the frequency range of the laser were able to be diverted around the object, then the laser wouldn't affect it.

    There might be other effects that would make me wrong, however. Strong lasers can ionize and heat the air, which might change the way the laser interacts with the mirror or cloaked object, I guess.
     
  6. Google AdSense Guest Advertisement



    to hide all adverts.
  7. Prince_James Plutarch (Mickey's Dog) Registered Senior Member

    Messages:
    9,214
    Pete:

    Is it possible to have 100% reflectivity?

    Thank you.
     
  8. Pete It's not rocket surgery Registered Senior Member

    Messages:
    10,167
    I don't know. If it could be done, I suspect it would be in a very narrow frequency range.

    Here's an Optical Engineering paper that talks about high reflectivity coatings. They achieved 98.7% reflectance (which I think includes scattering), so I guess 99% might be a practical limit with current technology.
    http://spiedl.aip.org/getabs/servle...00045000006063801000001&idtype=cvips&gifs=yes

    I don't know if there are theoretical limitations, or if better technology could approach 100% reflectance.

    Pete
     
  9. Prince_James Plutarch (Mickey's Dog) Registered Senior Member

    Messages:
    9,214
    Thanks for the information, Pete. I do appreciate it.
     
  10. Kron Maxwell's demon Registered Senior Member

    Messages:
    339
    I doubt that 100% reflectivity can be achieved. It's like an ideal machine.
     

Share This Page