Twisting The Light Away [Twisted Light]

New Scientist | June 12, 2004 | Stephen Battersby

[LTCJ]

Fire a beam of its laser light at the dust sitting on your tabletop and the dust motes will begin to dance around in circles. Fair enough, that's not quite a killer application.

Spoken by someone who's never seen the dust on my desk.

[spunkets]

Their modulation appears to be a variation of omega. They mention there is no discriminating reciever and I know of none that would distinguish this from FM(that includes AM and PM, since they really are FM). This is too, because they are varing omega. As you probably know, all detectors are sensitive to polarizaiton, but that sensitivity is dull. I don't think they have anything here.

[mikegi]

Circular polarization.

Nope, it's an interference effect.

[GOPJ]

Might work -- but the right signal might be more sophisticated yet. The path...

Martin Harwit, emeritus professor in astronomy at Cornell University in New York, has suggested we start looking for twisted light from space as part of the search for extraterrestrial intelligence.

[timestax]

[tjg]

"I thought that was an odd example of a way to send binary code -- how would you send two "offs" in a row?"

You could do it by tying the signals to a clock speed. For example the reciever expects a signal every second (or every microsecond, whatever) and if two seconds pass without a flash of light, that's two 'offs'.

[William Terrell]

Hah. From analog to digital and back to analog again, with moxie.

[forsnax5]

"I thought that was an odd example of a way to send binary code -- how would you send two "offs" in a row?"

You could do it by tying the signals to a clock speed. For example the reciever expects a signal every second (or every microsecond, whatever) and if two seconds pass without a flash of light, that's two 'offs'.

That is certainly correct, but the example given didn't include a clock. It states:

Many forms of communication use binary codes - if you have a flashlight, and you need to send a message to your friend, you only have the choice between flashlight on and flashlight off. There's just one bit of information per flash.

"Sending a message to a friend" with a flashlight implies a "lost in the woods" scenario. It would be done with morse code, not ASCII (binary).

Picky, I know.

:)

[SunkenCiv]

blast from the past

[SunkenCiv]

Sorry LibWhacker, forgot to remove your name from the "to" box.

[RJL]

I thought that was an odd example of a way to send binary code -- how would you send two "offs" in a row?

That would be the "nary" in binary. ;-)

[Redcloak]

I was asking myself the same question.

[LibWhacker]

No problemo; I like to see any new comments my old threads dredge up! :-)