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Communications Power Hardware Technology

UAV Hoisted Tower Powered By Laser Over Fiberoptic 103

carstene writes "LaserMotive, winners of the 2009 NASA power beaming contest, has a new invention, a virtual comm or surveillance tower. It's a quadcotper that can run indefinitely, powered by laser beam over a fiber optic cable. This allows the "tower" to reach great heights and avoids most laser safety issues."
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UAV Hoisted Tower Powered By Laser Over Fiberoptic

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  • take electric power from a cable, inefficiently convert to light, run it through a cable, inefficiently convert it to electricity, then use what little is left!!

    Why not just use the electricity and a copper cable???

    • Re: (Score:3, Informative)

      by Spazed ( 1013981 )
      Copper weighs more than a fiber optic cable.
      • Copper's resistivity would cause more energy to be lost after a certain length, too.

      • Copper weighs more than a fiber optic cable.

        Don't you still have to have additional cabling to support the fiber? I would expect that using plain fiber optic cable would break / stretch under it's own weight. I know my verizon Fios cable comes in bonded with a steel cable, and its just running in conduit in the ground.

      • by Khyber ( 864651 )

        REAL GLASS fiber optics are heavier than copper cable, with the approximate atomic weight of copper being 29 and silicon dioxide being 30 having two oxygen atoms at 8 and one silicon atom at 14.

        People that modded OP informative need to go back to basic chemistry class.

        • by Spazed ( 1013981 )
          Who said they were using glass? I've got two boxes of fiber sitting here, one glass and one plastic. Haven't touched the glass stuff in a few years, the bendability of the plastic just makes it a better choice. It is also about half the weight of the glass stuff. I would assume if this is meant for emergency or wartime use that it would be using the more forgiving, lighter, and more rugged plastic.
          • by Khyber ( 864651 )

            The plastic stuff is even heavier, (C5O2H8) for a total of approximately 54. Glass handles more power than pretty much every plastic given its lower thermal conductivity and higher tolerance to heat buildup.

            Extremely thin glass fiber can be almost as flexible as a plastic fiber, and carry more energy.

            • <quote>REAL GLASS fiber optics are heavier than copper cable, with the approximate atomic weight of copper being 29 and silicon dioxide being 30 having two oxygen atoms at 8 and one silicon atom at 14.</quote>

              <quote><p>The plastic stuff is even heavier, (C5O2H8) for a total of approximately 54. Glass handles more power than pretty much every plastic given its lower thermal conductivity and higher tolerance to heat buildup.</p><p>Extremely thin glass fiber can be almost as
              • by Khyber ( 864651 )

                Come back when you actually work with this stuff, okay?

                I laid the fiber optics and copper wires for our research facility in the UK. Fiber is HEAVIER, especially when you include the attenuation-controlling covering.

                Can't revoke a geek card when you've obviously never held real fiber optics or even bought a 50 kilometer spool of it.

        • The key is not mass density, but unit of energy per weight. Turns out you and put more energy though fiber optic then copper for a given weight of material.

        • What does the atomic weight have to do with anything?

          my gram of gold still weight much less than a pound of boron.

          A cubic meter of oxygen weights a lot less than a cubic meter of lithium.

          What matters is the energy density they can achieve, which has nothing to do with atomic weight.

    • Re:makes sense (Score:4, Informative)

      by onkelonkel ( 560274 ) on Thursday June 30, 2011 @03:02PM (#36626058)
      Fiber is non conductive. If you are going to fly your little drone in a populated area, you don't have to worry about your tether contacting overhead power lines. A lot of cranes and hoists used to have fiber to the remote controls for that reason. (A lot of them are wireless now).
      • Hmm, good point. I guess we should add a 12 cent fuse to the circuit...

        • Then you pop your fuse and lose your UAV?
          • by smelch ( 1988698 )
            Uh! No! Don't know you reading a 3 sentence paragraph qualifies all of us arm-chair EEs to know exactly where 12 cent parts can save billions for an application we know nothing about?!
            • by blair1q ( 305137 )

              Aside from the fact that us degreed EEs agree with him, you're right.

              • by pluther ( 647209 )
                A degreed EE should know enough about engineering to realize that not everything that goes into even something as simple as a power transfer system is going to be mentioned in a single paragraph.

                Chances are a project that employed an entire team of engineers for months or years came up with a few ideas that aren't even in the article, let alone the summary. I bet some of them had EE degrees, too.

              • by smelch ( 1988698 )
                Well, that and it was a two sentence paragraph. Also, a driver can also be a back-seat driver. He just needs to be in the back seat.
      • There is no such thing as non-conductive - all depends on the voltage applied. It will become very conductive once the lightning strikes it.

      • Should the sheath get wet due to rain or condensation it will be conductive. Also the conductor of power cables have a sheath of non-conductive material just like fibre optics.

        Is the weight of the equipment required to convert laser light into electricity less than the difference between the weight of a ferrous conductor vs fibre optics. If the conductors were aluminum they may even weigh the same.

    • by whit3 ( 318913 )

      You don't want to use electric power on a copper cable,
      because of lightning. I'm thinking there will have to
      be 'running lights' to warn aircraft at night, too.

    • by Anonymous Coward

      Electricity -> light conversion by a laser diode is around 50% efficient. For a single wavelength, light -> electricity conversion efficiency isn't too far from the same figure. Thos gives a ~25% efficiency: not so bad, especially when you take into account the low power loss in hundreds of meters of thin plastic optical fiber compared to a long 2-wires copper circuit.

      • by Khyber ( 864651 )

        HVDC or HVAC are pretty much near-lossless for energy transfer, that's why they're used as California's primary energy transmission backbones.

    • fiber optic cables won't attract lightning?

      (unless they are wet I suppose)

  • ...is that you have to retract the UAV during a storm. While it's retracted, you've lost the UAV's capability. So, I can see these deployed in emergencies when you need comms fast. But eventually you'll want to build a tower.
  • Atlantis (Score:4, Funny)

    by lymond01 ( 314120 ) on Thursday June 30, 2011 @02:52PM (#36625910)

    Atlanteans had this tech back in the 10,000 BCs except they didn't bother with a tether, they just beamed their maser (that's Microwave amplified...) energy through crystals seated on top of large pyramidal buildings. We're so 20,000 years ago.

    • Atlanteans had this tech back in the 10,000 BCs except they didn't bother with a tether, they just beamed their maser (that's Microwave amplified...) energy through crystals seated on top of large pyramidal buildings. We're so 20,000 years ago.

      Well, that's the problem with marketing ... sometimes "new and improved" means features everyone else has had for years. ;-)

      (And, as anybody who has ever worked on a project to replace something on a mainframe can attest ... it'll be over budget, late, cost 10x as muc

    • Ignoring the fact that there are no facts, your math is wrong.
  • Hovering sharks with frickin' laser beams?

  • by Animats ( 122034 ) on Thursday June 30, 2011 @03:04PM (#36626072) Homepage

    Tethered ground-powered rotor-lift platforms date back to WWII. Israeli Aircraft Industries [iai.co.il] has one in their product line today. They're usually installed on the back of a vehicle, so you can pop up the camera unit and take a look over the next hill. Early versions had no guidance and just used enough power to pull the tether taut. Modern ones fly actively, so they can be used to peek around buildings.

    Using a fiber optic to transmit power is rather inefficient. Probably 70% - 80% of the power is lost that way.

    • Re: (Score:1, Informative)

      by carstene ( 267166 )

      Main advantage of fiberoptic is two fold, first it is lighter then copper per unit of energy you can push through it. Second it is has no electrical resistance, so you don't get a huge voltage drop over long distances. What this means is you can have more payload at greater height then with a copper based electrical solution.

    • by Geminii ( 954348 )

      Ah, but it means the UAV isn't lugging batteries and can keep aloft using less power and for as long as you want.

      I'm actually wondering about something like an Eva or laptop system - have onboard batteries, but power the device through the tether up to the point where it needs to progress beyond the tether's range.

      Additional fun - have the end of the tether attached to its own UAV so the tether doesn't just drop to the ground and/or get caught on something. And as long as it's purely tether-powered, sti

  • by llZENll ( 545605 ) on Thursday June 30, 2011 @03:06PM (#36626126)

    Why not just use a balloon? The only advantage I can see this having is less movement due to wind, but designing a properly shaped balloon should easily defeat that, and more importantly a balloon would be much quieter at low altitudes, use much less power, and stay aloft even if the power is cut. Seems like a case of a hammer looking for a nail.

    • The fiber optic cable is the main advantage here. It gives you better data transmission to the airborne antennae. But in order to really facilitate that, the system probably needs better stability in wind than a balloon. (This is admittedly a SWAG.)
      • No reason a fiber optic cable cannot be tied to the balloon.
        • Apart from this little thing we call "wind". A quadcopter can compensate for wind in a way a balloon cannot (surface area is the balloons biggest weakness). Also for a 24/7 balloon you would need a pipe for lifting gas (Helium is a slippery customer) in addition to the one for powering the equipment.

          • by M8e ( 1008767 )

            Hot air balloon.

          • You could do without the pipe, if you allowed for a little maintainance: Someone gets to come around every week or so, haul in the tether and refill the balloon. It's not cheap though, and rather fragile.
          • by llZENll ( 545605 )

            Both issues are easily compensated for: 1) wind, simply design a saucer shaped balloon with very low wind resistance, furthermore you could have a rotatable properly for exact positioning 2) simply store a small amount of helium on a tank which controls altitude

            • by spydum ( 828400 )

              I have to agree -- dirigibles seem like a much more elegant solution -- not requiring a lift power source.

              I mean, everyone talks about the power to send up to the copter -- but after that power is spent on lifting the damn thing, what power is left to do any useful work? communication towers, especially transmission towers require a fair amount of power all by themselves.

    • Balloons get really big fast as you add payload. This means that more and more of your energy is used for station keeping rather then payload. Also with the UAV solution it is small and light enough to say fit in the trunk of a car and be handled by one person. For a balloon to carry any practical payload it is large enough where one person can no longer handle it on there own.

    • But balloon would not make a news and it is so low tech. Lasers, on the other hand, are awesome.

    • by Nobo ( 606465 )
      When they're both 1500 ft up in the air, a person on the ground can easily see the balloon it takes to lift 1500 feet of fiber and a sensor package, but can't see the spindly four-rotor helicopter it takes to do the same.
    • by juancn ( 596002 )
      I can think of a few:
      1. Size: A balloon with a decent payload has to be big, which makes it easy to spot from a distance. Check the name "InvisiTower", the idea is that this is smaller.
      2. Rapid deployment: Inflating and deflating a ballon is an operation that takes some time. A thing like this mounted on a vehicle can presumably be deployed in a lot less time with a single operator.
      3. Wind resistance: A large balloon is very hard to handle with even slight breezes.

      There are probably other advantages that I'm miss

      • Rapid deployment: Inflating and deflating a ballon is an operation that takes some time.

        It takes less than one second to inflate a balloon with a compressed helium tank. The other things you've said make sense but this doesn't even come close. (You could also make the balloon transparent, which would reduce visibility.)

    • by Kamiza Ikioi ( 893310 ) on Thursday June 30, 2011 @03:31PM (#36626474)

      Because a balloon, at best, is filled with Hydrogen, and doesn't carry a lot of weight. This is for surveillance, possibly covert. Flying a giant balloon from a ground station in a forest outside a Colombian drug lord hideout wouldn't be the wisest move.

      A copter on the other hand can be small, nearly silent, and left heavier equipment without nearly the visual footprint. It can also be rapidly deployed and returned for "quick looks". It can be taken to an exact height and location, not blowing around, and would not need tanks of gas brought around with it... A laser hooked up to a generator would eventually be safer and more portable and reusable in a battle or disaster.

      It would also be much easier to remote control, turn the camera. What use is a balloon at say, a nuclear disaster zone like Japan, if the camera isn't stable enough to actually zoom in remotely without making the operator throw up?

      • Hmm... could you make the balloon out of thin, transparent plastic for a tiny visual footprint? I know it'd leak out fast, but for an emergency battlefield comms relay a couple of hours might be all you need.
      • by rossdee ( 243626 )

        "Because a balloon, at best, is filled with Hydrogen"

        Baloons these days tend to use Helium, its not flammable. I guess a baloon would be easier to spot though.

      • create a single molecule the size of your balloon, last stage of assembly, remove the gas molecules within.
        (kinda like the pupeteer space ships, a single molecule of very large proportions.)
        so long as it's strong enough to withstand the crushing force of the vacuum
        Hell, use that really strong material known as aerogel.. either way, have the gap space be a vacuum

        it would lift a hell of a lot more than hydrogen....

        • Not really. Your lifting power can never be more than the weight of air it displaces and hydrogen is already a whole lot less dense than air. If you do the math a complete vacuum will only lift about 7% more than hydrogen. Even then I don't think there is any technology that will give us light containers that can withstand vacuum pressures of any usable size.

    • by Timmmm ( 636430 )

      Or you could simply have it land periodically and swap batteries. Much simpler I would think.

    • Besides the other comments, one interesting idea is that this is relatively small and unobtrusive.

      A few years back, someone wanted to put up a cell tower. The complaint wasn't with the radiation or any of that. The complaint was that the tower was ugly and a destroy the local scenic beauty. While I certainly admit that I think five bars on my cellphone is pretty attractive, I can see the argument.

      So something like this could be useful: A building with a fiber optic cable going up a few hundred feet to a

  • What's the point of a heavier-than-air, tethered, actively powered, stationary platform?

  • Seems to me that a good copper wire and high voltage AC would be far more efficient and at a high enough voltage the wires could be very thin and still deliver loads of power..

    Instead of converting electricity to light and back again, just keep it electric.

    • What if you never converted the light to electric in the first place. Just collect enough light from the sun and beam it into the fiber (assuming solar panels are too big/heavy for the drone...) I suppose the whole data transmission aspect of it would be quite a bit different in that case. It also wouldn't be as useful at night.

  • by scrib ( 1277042 ) on Thursday June 30, 2011 @03:19PM (#36626328)

    One of the advantages of this design over a lightweight copper power feed is that DATA is bidirectional over the same optic cable. Transmitting the surveillance data back to the ground is much more secure and at higher rates than through thin copper or over some RF transmitter on the copter. That is, this can be stealthier.

  • I couldn't seem to find any references as to the size of the payload this device can hoist up to 600 feet. I mean it's cute and everything but if it can't fly when you add a camera, exactly what kind of "surveillance" do you plan on doing with it?
  • I was actually hoping that wireless transmission of power didn't mean there was some sort of big cable connecting the transmission endpoints. But I see there are just no wires in the big "wire" that connects the drone to the ground.
    • by blair1q ( 305137 )

      You are correct. This article is kinda stupid.

      A laser beam without a fiber weighs nothing (in fact the photons have momentum which can be counted as lift at the receiver on the underside of the copter) and can probably be run at about 100X the power the lasers going through the fibers for this thing can. It also wouldn't be a serious contributor to the dynamics of the vehicle. 100 meters of fiber in any kind of breeze is going to add appreciably to the effects of wind and gravity, and form a huge reactive

  • They clearly only need one fiber to deliver the energy, but would need two copper conductors. I wonder if there's a way to deliver the energy over one copper wire.
  • by fahrbot-bot ( 874524 ) on Thursday June 30, 2011 @08:50PM (#36629686)

    The critical factor behind InvisiTower is laser power beaming, which involves the wireless delivery of electrical power over long distances via laser beam ... In this case, laser light is beamed through the fiber optic cable and converted into electricity at the aerial platform.

    Um. The phrase "wireless" must mean something completely new.

  • Does one really save weight by transmitting laser power through an optical fiber versus using a lightweight electrical cable (maybe silver?) at a relatively high voltage? Even after the losses involved with converting the light back to electricity at the copter (probably about 50%)?

    Serious question, is the power density of optical fiber really that high?

    I've seen this technique used for sensors (http://spectrum.ieee.org/energy/the-smarter-grid/electricity-over-glass), wouldn't have thought it would work wel

  • maybe if the fiberoptic is a good insulator, it will be less likely to try to carry current to the ground and blow the helicopter and ground station to bits. This would make it safer in areas where there are power lines. It also might make it safer when the weather is not so nice.

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