UAV Helicopter Flies 12 Hours Charged By Laser

garymortimer writes "LaserMotive (who last year won $900,000 in the NASA Power Beaming Challenge, one of the levels of the 'Space Elevator Games') have teamed up with Germany's Ascending Technologies to create an indoor flight record for electrically powered multicopters. The flight took place at the Future of Flight Aviation Center in Mukilteo, WA. LaserMotive is a Seattle-based company developing laser power beaming systems to transmit electricity without wires, for applications where wires are either cost prohibitive or physically impractical."

Comments

Because the laser would be all burninaty

[Sycraft-fu]

The max safe amount for a consumer laser pointer is in the 5-10mW range. Above that, serious and rather immediate damage can result from looking at it. Up in the range of 500mW they are dangerous to the point that reflected light can cause immediate eye damage. So you don't even have to look at the beam, just a specular refraction and still can get hurt. Also, this starts to get in to the "can set shit on fire" level.

Now consider that a laptop power adapter is generally in the 50-100watt range. In terms of lasers that would be "CO2 laser that blasts through steel as though it were butter."

To power anything more than a very trivial device, you'd have an unsafe level of laser power. Also it would be even worse than it sounds, because of course the receiver won't be 100% efficient.

Re:Because the laser would be all burninaty

[OeLeWaPpErKe]

Incidentally, this problem has been solved. Simply de-focus the beam at the sending end, and re-focus it at the receiver side (and do it with a diameter lens that nobody except godzilla has in their eyes - easy enough).

The goal is to spread, say 100W, in a beam that has a surface area of, say 10cm2. Since the aperture of the eye has a surface area of about 10mm2, the power delivered into the retina if someone were to glue their eyeballs to the transmitter would be 100W * 10cm2 / 10mm2 = 1W (and the eye will immediately respond by lowering that surface area to less than 1mm2, making the total delivered power less than 0.1W, and obviously, even with your retina glued to the transmitter you won't get anywhere near 10% efficiency).

Directly looking into the sun delivers about 2W to your retina (and will destroy it, but not immediately).

This is a big problem for the "solar panel in space" technologies. But it's not much of a problem really. If you were to send down 100 GW over a square kilometer, anyone could walk over the receiver perfectly safely without any protection. The power from the satellite would be a factor 1 million less than the solar irradiation (so you could send it quite safely over 10 square meters as well if needed).

Clarification needed!

[Paradyme]

I understand the concept behind this, but how do they keep the sharks pointed at the helicopter?

Re:The unstoppable weapon

[Shark]

Okay... Now I'm involved, you happy?