Optical Cellphones

foondog writes "Here is a story over at News.com about optical cellphones. It seems that the Department of Defense has given a grant to the University of California to develop optical cellphones that are faster and more secure. This sounds a little strange to me since you would need a line of site with no obstacles in the way to use this. The article doesn't explain how this might work."

Comments

LOS

[Wyatt Earp]

"It seams that the Department of Defense has given a grant to the University of California to develop optical cellphones that are faster and more secure. This sounds a little strange to me since you would need a line of site with no obsticals in the way to use this. The article doesn't explain how this might work."

What about from a soldier/spy/diplomat straight to a comm sat?

It's easier to get line of sight to orbit.

Re:LOS

[tomhudson]

The right-angle mirrors (the ones left by the Apollo missions) on the moon are about a meter wide, but the laser beam, at least for the Apollo experiments, was about 2 miles wide when it got to the moon. Even collimated laser light spreads as it travels.

Re:actually, no.

[spike hay]

X-rays are light energy, and they don't seem to have a problem passing through.. well.. you, among other things.

Um, xrays, gamma rays, optical light, radio waves, and everything else is electromagnetic radiation. The penetration ability changes with different wavelengths. Low frequency, long wavelength radio waves penetrate through objects very easily, this is why 2.4 ghz 802.11b goes through walls better than 5 ghz 802.11a.

Higher frequence microwaves, infrared, optical, and UV em radiation is basically line of sight. Ultra high frequency, high energy, sub microscopic wavelength xrays and expecially gamma rays can penetrate most materials due to their high energy.