Like uBeam - but with safe IR lasers

[matseng]

Just ran across this... http://spectrum.ieee.org/tech-talk/consumer-electronics/portable-devices/wicharge-promises-phone-charging-by-infrared-laser

At first glance it sounds just as practical and viable as uBeam - using a Class 1 (eyesafe even when viewed thru microscope/telescope) IR laser to charge your phone?  How many microwatts of power will then reach the phone?   Or can you make a Class 1 laser with a few watts of output and still be in spec?

I thought that stuff from Israel usually could be considered quality leading edge hi-tech, and also that things published at ieee.org are more or less legit and not gawker/engadget-style marketing fluff. But?

[Brumby]

Power is power. Even not stimulating visual sensor cells, it still can burn.

My reflex reaction also.

[coppice]

Class 1 lasers are not limited by power, but by the exposure they can result in. This new wireless power scheme uses an external cavity laser, where you could enter the cavity if you get in the way. As soon as you do the  laser will stop lasing, limiting exposure. Trying to get this to work might be a challenge, but I don't see anything crazy.

[matseng]

Ah yes....  But the still means sending a 10 watt beam across the room and since only 10-15mW is classified as "dangerous" it would be enough for 0.1% of that beam gets diverted and you'd be in the unsafe zone.  Maybe they can detect that 0.1% of the beam power got diverted, but I guess that also a slightly dusty or smoky environment could attenuate the beam power by 0.1%.

Maybe this will work, but it sounds a bit to be like a solution looking for a problem to solve...  Remote charging of a phone....

[coppice]

Ah yes....  But the still means sending a 10 watt beam across the room and since only 10-15mW is classified as "dangerous" it would be enough for 0.1% of that beam gets diverted and you'd be in the unsafe zone.  Maybe they can detect that 0.1% of the beam power got diverted, but I guess that also a slightly dusty or smoky environment could attenuate the beam power by 0.1%.

Maybe this will work, but it sounds a bit to be like a solution looking for a problem to solve...  Remote charging of a phone....

10-15mW of coherent energy may be dangerous, but it takes as lot of non-coherent infra red to be considered dangerous. Any obstruction of the cavity by a human, animal or inanimate object will bring down its gain and the lasing will stop. Any obstructing  object which reflects the energy off in the wrong direction will stop the lasing. That's the whole point of using this external cavity technique. What intrigues me is whether they can get the mirrors reflective enough to get lasing to start in the first place.

[Brumby]

An open air laser cavity...?

Intriguing idea - but I'm curious about the mirror requirements and beam aiming at the transmitter end.  Certainly they have the retro-reflective structure, but that just deals with aim for a beam that is in flight, but how do you get the power heading in the right direction in the first place?

Also, how much of a problem would mirror contamination pose?  My understanding is that mirror performance for lasing needs to be pretty impressive.