

US Navy underwater laser development "changes everything" - cwan
http://www.strategypage.com/htmw/htsub/articles/20090910.aspx

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windsurfer
I remember reading about the importance of sub-millisecond shutters in
underwater photography. Apparently, if you time the flash and shutter _just_
right, you can get the light bouncing back from the target into the camera,
but block all the light from in front of and behind the target, as well as
ambient water particles . This apparently increases your visible distance
underwater by twofold.

~~~
giardini
Note that here the laser is used to generate an _acoustic_ pulse, so the light
is not used as a carrier, sound is.

Research in using lasers underwater for 40 years with the same result: little
use other than for very short distances. Water absorbs the energy too much for
lasers to be of use at long distances. And high power emissions only make you
look like a searchlight, hardly something you want to do if you're in a
submarine.

I cannot see that this "changes everything".

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goodkarma
>> To do this, the sub releases a similar buoy through its garbage chute.

This is technically incorrect. The garbage shoot is for weighted trash that
gets flushed vertically downward. If the sub were going to launch a buoy it
would send it upward via one of its 3" signal launchers (used for flares,
other buoys, etc.)

~~~
jonknee
Though they did note that the buoy hovers for a while so the sub isn't below
it when it rises to the surface. Considering the delay it could be deployed
above or below the sub, but below may make more sense because it won't float
up on its own.

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Engine-uity
I wonder if this technolgy will provide an alternative to communicating with
satelites in space. I think using this underwater laser system is great
because it provide security from signals being intercepted.

~~~
streety
I don't believe this is relevant to ground-to-space communications. The way I
read the article the laser pulse has a short range, ionising the water in the
vicinity of the buoy, which creates sound waves which emanate out to wherever
the sub is. The laser isn't bouncing back and forth from sub to buoy.

As the communication is via sound and not laser it also means that anyone else
in the vicinity could intercept the message. Strong encryption and
authentication would still be required.

