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The Internet

Broadband By Laser: Promises, Promises 83

Digital Quartz writes: "There's all manner of ways to get last-mile broadband access these days, from cable to DSL to microwave, but QuantumBeam, a Cambridge based company, wants you to surf by laser. Check out the article at The Wall Street Journal. I wonder how well it performs in the rain?" The promise of optical wireless is alluring, but it's also been said before ... I hope it actually pans out before it becomes old tech.
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Broadband By Laser: Promises, Promises

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  • Also, I don't doubt that these lasers would cause increased ionization of atmospheric oxygen, leading to even further breakdowns in the ozone layer, as well as a host of physiological problems for all higher life-forms.

    Given the choice, why on Earth would they pick a laser frequency to which the atmosphere wasn't nigh transparent? The whole point is to minimise signal loss. I'd be more worried about your microwave oven.

  • There's also this article on CN today about another vendor

    http://www.cnn.com/2001/TECH/internet/02/27/tera be am/index.html
  • Telecoms and startups have had things like this well into the design stage for at least a year or so. I remember seeing bird-house like megabit laser arrays in Wired as far back as 1999. The idea was always that a grid of such arrays could provide a broadband net across a major city and provide fat data pipes for corporate customers without having to tear through the infrastructure at tremendous expense. I think these devices are made by AirFiber or TeraBeam and are now being taken to market. If I recall they got around the bird 'problem' by using redundant transmitter/detectors in a single array. Either the tech discussed in this post is some new twist that I'm not fully appreciating or just old tech masquerading as a breakthrough.
  • I don't suppose that laser's would work very well in the rain but is there any possibility of an under ground laser network? Like through pipes and stuff all built under ground. Or is that not viable?????
  • Um. Infrared is not the same as X-Rays, gamma rays, etc. It would be absorbed by the washer's skin or clothing.

    This is as dangerous as aiming a case of remote controls at your groin.

  • In 1993 I was working on "The Big Dig" - an extremely large construction project in Boston slated to be completed in 2004. During that year we needed to set up a network link between South Station and 185 Kneeland Street. In good weather it was a godsend. The roads and telephone lines were constantly being chewed up and thus unavailable for a hard link. However in light snow and light rain the network became very slow. This is in 1993 at 1993 levels of network traffic. Whatever technology they have it needs to be really kick ass. The level of weather that would disturb this thing back then was minimal and the only thing keeping this in place was absolute necessity.

    --Peter
  • It's called Fiber optic. If you go to the trouble to dig a hole in the ground, you might as well make the most of it and string fibre through it.

    Down that path lies madness. On the other hand, the road to hell is paved with melting snowballs.
  • Does anyone know if RF wireless technology, such as 2.4 GHz that is used in cordless phones, can be adapted to provide such access, say if enough neighbors installed them so a P2P net reached to someplace with a wire connection?

    Sure can. 802.11b (Apple Airport, Lucent WaveLAN, et. al.) is a 2.4 GHz system and has a data rate of about 11Mbps. It can be extended to a distance of a few miles if you use a higher-gain directional antenna. Here's [slashdot.org] a slashdot article that talks about some folks in Australia who did something like this.
    _____________

  • Wiring has noise problems, plus you have to install special crossovers to get past transformers in large buildings. There are commercial systems that use wiring, but the bandwidth is not that high. Last time I checked, about 6 years ago, it was hovering around 9600 baud. Anybody have more recent info?
  • Fiber Optic, hey. Sounds like mumbo jumbo to me. ...... Just joking. Sorry, That should have clicked in my head... but I'm a little slow most days. Thanks.
  • Heh, if I wasn't already paranoid about flying -- now I gotta worry about the pilot being blinded by the laser transmission of some schmucks porno-packets.
  • I like to know people's experiences with technology like this.
  • If you haven't already gone blind from surfing for too much pr0n,
    you certainly will by looking directly into your connection.

    Of course, my laser pointer has been able to communicate for years: . . . - - - . . .

    -WetDog

  • http://www.terabeam.com/our/ This is Optical IP over in Seattle. This site has some more information on how they do it and whether we are just flooding the Airways with more shit.
  • LCDs change the polarity of the light passing through them when as charge is applied, maybe something related could be the answer.
  • I dunno wether that post about total internal earlier was sarcastic or genuine, but either way, I think he's got a point....How is shining a direct laser to transfer data different from shining a beam of light through a fibre, other than that it is incredibly less convinient???
  • well the .co.uk address is a bit of a give away ;-)
  • Which is easier, revising the old easy laser / RF communications technology or searching for new way of wireless communication (quantum inseparability sounds like scifi, but is it really that far off? =P). I'm generally opposed to this idea, as it leaves room for lawsuits such as when a private plane is flown across the path during a fog, or if a person steps in front of the transmitter, the entire system fails. Creating redundant links seems to be an easy solution at merely postponing the inevitable network outage. It's too shaky for any sensible company to bother not spending the extra money on getting fiber run. Until anyone can provide me with a wireless solution that replaces fiber and is stable, I'll stick with my good old light data... =)
  • Since this is "not the newest technology out there", one would think that it's possible to go out and buy one?

    I'm actually in the process of building a local point-to-point radio link *right now*, so this interests me. We have a 3-mile distance we need to get at least a STM-1 over and NEC is quoting us a four-month lead time for their 26GHz STM-1 radio links. I can't wait that long, so I'm looking for alternatives. Can someone recommend a solution for STM-1 -level point-to-point connectivity that is available *today*?
  • I'd be happy to get any broadband at all. It's pretty ridiculous to start talking about 'faster' broadband, when most of the country(US) is still using 33.6K modems.

  • I do belive the idea is that you put up this system between skyscrapers in cities. That way reducing the need of cabling. And they get cheaper broadband access. The article mention that the range limit in cities on tall buildings would be 1500 feet. Its not a consumer product. And i dont think comsumers need all this bandwith either(100+ mbit). Radio access is just as well for us. Tough it might be an option for huge apartment buildings in Manhattan etc..
  • It's way not new. Back in the mid 70's the University of Colorado was using a laser to transmit data from the computer center to the engineering building printer more than a mile away. Most of the time it worked well, but when it was snowing heavily you couldn't get print.

  • I can't see short distances being the use for these. It would be easier to make a parabolic mirror with an led to do the tx. This would make a larger beam, less susceptable to weather, but not as strong as a laser which would be better for long distances. Plus, someone in this thread mentioned fiber: fiber has to be laid. The point of wireless is to not have to lay fiber.

  • Metropoli have human population density distributions akin to the fairy ring fungus [ucdavis.edu].

    So, while city dwellers in the dead core have buildings to block their lasers, they are consoled by the relative lower cost of installing wire for the last mile, be it cable or a separate DSL connection.

    I live in the pleasant semi-rural `burbs where my phone monopoly's C.O. doesn't provide DSL and where the cable TV stops about 1 km from my house. I'd love to have broadband access and can't get it under the current business model.

    I'm willing to pay up to about US$100/month to get that access, but I doubt this technology satisfies that criterion yet.

    Does anyone know if RF wireless technology, such as 2.4 GHz that is used in cordless phones, can be adapted to provide such access, say if enough neighbors installed them so a P2P net reached to someplace with a wire connection?

  • You do not actually have to lay the fiber. Image that you wanted to connect two building but didn't own the land between them (possibly bisected by a road). Then you would want a wireless solution, although not this one, as there are better short range solutions. Let's say they were miles apart, then you would need something like a laser that does not degrade over great distances. I agree with another post stating essentially, that the TCP protocol will handle the data loss, and UDP data is (should be) designed to do well with a little corruption (a raindrop may screw an instant of voice data up, but it won't really be noticed by the listener (and you thought digital meant no quality loss, ha!)).
  • by Nastard ( 124180 )
    Laser pointers: They aren't just for fucking with cats anymore.

  • Why are you using a laser for such a short distance? There are many shorter distance viable wireless technologies that would be resistant to your heat problem.
  • Great link! Here's more:

    http://www.alphalink.com.au/~derekw/upntcvr.htm
    http://www.hut.fi/Misc/Electronics/circuits/laser l ink.html
    http://www.k3pgp.org/

    Another site worth going to if you are interested in lasercomm stuff:

    http://www.repairfaq.org/sam/lasersam.htm

    Finally, one that appears to be dead (?) is Ronja. In my opinion, this is one of the best projects out there - if it is still going. IIRC, it uses both lasers and high-brightness LEDs for the system. From the opencollector.org DB:

    Ronja 115 Loopipe

    Category: design
    Clock 4 November 2000; 19:02

    Ronja connects two PC's point-to-point, using visible light. The design is very simple, building is easy and complete guide will be availiable on the Web.

    Schematics are availalble in the moment. Suitable for anybody who wants to communicate entirely freely in a direct line of sight. Building is cheap and requires only common tools available in home workshop. Communicates 115200 bps full duplex over 260m, but new, stronger version Ronja 666 Lucifer is in development.

    Update

    The Loopipe construction with HSDL1001 frontend has been successfully verified by another person, Pavouk.Two bugfixes resulted. He also designed a PCB. Pavouk tested the electronic part (not the optics), with success. The XTAL oscillator has been redesigned and HSDL1001 frontend was built for the first time and proved to be functional.


    http://atrey.karlin.mff.cuni.cz/~clock/r0nj4

    ---

    I remember the link working at one time though. I managed to get a copy of the info on the site. If anyone can confirm if the site is dead, alive, or moved, please let me know...

    Worldcom [worldcom.com] - Generation Duh!
  • Better hope you don't send out a bad packet else you might kill someone...

    Actually, I think that would kind of be bad, somebody could mess with your internet connection from outside of your house, shine their own lasers at it, etc. Open a whole new avenue of hacking. You could also probably read the laser stream somehow..someday anyhow, I don't think it would be very secure..well...not like anything else is anyhow.
    -----
  • http://www.cnn.com/2001/TECH/internet/02/27/terabe am/index.html Just making sure that the link is correct. There was white space inside the word terabeam.. terabe am.
  • There was an article here a while back on exactly that.
  • I wonder what sort of creative technique would be needed to illicitly packet sniff one of these networks. Perhaps one could take a partly-reflecting, partly-transmitting mirror and bounce the transmission to a receiver to tap the signal. Of course, a small radio-controlled dirigible would be required to position the mirror!
  • Freespace optics is fun. Ahh...the days of modulating a HeNe with FM radio...

    Actually, there are significant challenges, especially if it's limited to 100 mW. I should also mention 100 mW IS NOT eye safe. In fact, you can readially feel 100 mW of any wavelength on your hand. Remember, your eye focuses things. Would you like 100 mW per few mm^2 on your retina?

    I'd also be interested in atmospheric affects including interference from solar and harmonics of streetlamps interfering with the modulated signal. They're going to need to do some very good noise reduction, but its definatly possible.

    Divergence would also be an issue. The pencil thin 100 mW beam will soon be spread out tens of feet over several miles, even when collimated very well. Can they manage to detect a few hundred microwatt signal further distorted by transient conditions?

    Another issue is line of sight. How are they handling this? Most cities and rural areas don't have a 5 mile line of sight at any height or location. I can hear it now:
    "Tell that guy to move his truck! He's blocking my Quake game!"

    This seems like a technology better left to the universities, special conditions, or enthusiasts. It might also be an OK idea for transmitting between ISP buildings. In a case where two buildings were across a busy street, it would be very easy and fast to connect the two networks via laser, instead of pushing expensive cable. Remember that you can modulate most diodes (even >100mW) in the gigabit range. There are also a few places where a few tall buildings sit in deserted places, seperated by several miles. This would be a good solution -- as long as it has line of sight.

    I just don't see it as practical technology for consumers. Possibly beaming to a satellite would be better, but even a multi-watt Argon can't penetrate clouds, and then there is the reception issue. It just doesn't pan out.
  • by KurdtX ( 207196 ) on Tuesday February 27, 2001 @02:25AM (#399297)
    I guess this means that if I try to check the weather online in the morning and I can't get through, it's already gotten bad.

    Kurdt
  • by Kj0n ( 245572 )
    I think it will behave quite nicely in the rain, especially when the distances are not too large.
    In my opinion the chance of a very small laser beam being hit by a rain drop are very small. Network protocols should be able to cope with that.

    Maybe the eruption of a vulcano could distort the laser beam, but I don't think Internet access is your first concern in that case.
  • Success will depend on where this technology is deployed. Examples of showstoppers:

    - Heavy rain
    - Fog
    - Snow
    - Heat radiation (distortion)

    Performance will of course be better over short distances. I wouldn't want my connection depend on the weather, but then Sweden might not be the ideal place to try it...

    /J
  • by Jules Bean ( 27082 ) on Tuesday February 27, 2001 @02:28AM (#399300)
    I'm afraid that's not quite to the point...

    In fact, electrical impulses propagate down the wire at a speed much faster then the motion of the electrons themselves (which as you say, is around 1 to 2 m/sec). Depending on the medium, electrical impulses typically propagate at 10-90% of the speed of light, I think (I don't have figures handy).

    This is because what I'm calling an electrical impulse is essentially a ripple in an electro-magnetic field: also known as a photon.

    Consider transatlantic, for example. About 5000km, which is 5 million meters. At light-speed, that would take about 17ms. In fact, my ping time to US sites can be as low as 70ms -- so my internet conenction already has 50% lightspeed latency.

    In fact, latency is more-or-less orthogonal to bandwidth anyhow (compare bps and baud, not that anyone gets those terms correct anyhow).

    Jules
  • by Anonymous Coward
    This is wonderful idea! Using light to send data, simply amazing.

    But I wonder, whether it's possible to use this phenomena I learnt about in physics class called "total internal reflection", and send the laser through tubes of glass instead? This will totally fix the problem with pigeons flying through the laser. So how about this, "laser through glass" for broad band???
  • It's true that electrons travel at a speed of a few meters per second, but the electrical current goes about 200.000 km/sec. Usually the difference between c and 2/3 c can be neglected.

    Besides, there are already other technologies (such as fiber and transfer through satellites) that use light (or electromagnetic waves) as a medium. They don't seem to be much faster.
  • by seizer ( 16950 ) on Tuesday February 27, 2001 @02:28AM (#399303) Homepage
    Pardon me if I'm wrong, but I had this strange idea that lasers require a direct line of sight. Any bouncing, and they lose their coherency.

    So.

    How the hell is this going to solve the "last mile" problem? For consumers in fairly large metropolises (any other takes on the plural?) there are too many bloody buildings in the way. Plus, the problem has already been solved with DSL, cable, etc. For consumers not in the last mile - well, the laser's going to max out at 5 kilometers, right? So those farmers still plodding along on a 28k are going to stay plodding.

    I fail to see how this can be of any use at all.
  • There is no problem.
    We run wireless access at 34Mbit and the signal is only 3 watt.

  • by DavidpFitz ( 136265 ) on Tuesday February 27, 2001 @02:25AM (#399305) Homepage Journal
    This is not the newest technology out there...

    Lucent have a division called Lucent Optical [lucent-optical.com] which are (unsurprisingly) world leaders at this sort of thing.

    A good article about what they do can be found here [business2.com]

    Incidentally, a company called Global Crossing [globalcrossing.com] plan to implement a network based upon lasers.

  • Moreover, the photons don't even travel at 300.000 km/s since it's no vacuum in fiberglass
  • The market here really isn't the consumer with no cable / dsl access - the limited range on these really prevents much use there.

    But inner city networks, neighborhood networks and companies with dozens of buildings sitting around eachother (Microsoft, Sprint, IBM...) who need this most.

    I would think these would be difficult to setup though - microwave is rather picky about aim.. I'll bet these lasers aren't much nicer.

    Now, load-share a few of these puppies for some REAL speed - YEAH! Perhaps the next internet backbone would be a large hollow pipe will lots of little lasers blasting through it instead of expensive fiber.
  • http://www.cotse.com/2152001.html this story is cooler :)
  • ..from the local council. We once considered a 155 Mbit link between to offices - but tell the local council it's laser and they start thinking Star wars (of the Reagan kind). And then there is the optical issues with heat off roofs and stuff - it get's hot here =))
    --
  • how does this have an advantage over optical fibre.. and microwave.. since microwave has lower wavelenghts.

    Early to rise and early to bed makes a male healthy and wealthy and dead.
  • Well, if you look at the very end of the WSJ article, there is a table of thetop dozen or so companies in the field. Too bad they didn't provide links.

    So it looks like it is growing, but not so much that we have to be worried about standards. YET.

    Standards are going to be important. I would hate to imagine what would happen if you had multiple receptors from multiple companies that were not highly directional (like lasers, etc). The problems of crosstalk or interferance from competing systems in the same space would be rather bad.

    heck, I wonder if they would be vulnerable to jamming?

  • Back in 1985 when I was in Cambridge at a little company named Symbolics (the first registered .com domain for you trivia buffs) we got our network connectivity over an IR link from MIT. This is probably very similar to what they'll be doing with the laser links. Our biggest problem? Window washers! Typically for an hour a month the rope/washers would block the beam and we'd be down. Took a few months to figure it out.

    Just because my intelligence is artificial, doesn't mean my problems aren't real.

  • Except that it might be interesting for faster and more reliable communication in space maybe ?
  • Then create a network of laser beams atop all the buildings and have a large, city spanning LAN.

    Sheesh do I have to think of everything?
  • FYI, Fiber Optic has less attenuation than air and can be bent around corners. Attenuation in a bent pipe is pretty high ;-)
  • I would have thought they had some sort of active aim, to compensate for heat distortion, tall buildings swaying in the wind?

    The only problem with that is that moving parts are a maintenance nightmare. Anyone know whether there exists technology to redirect laser in w/o a moving mirror (akin to sweeping an electron beam over a fixed area by applying a varying charge field). I think gravitational lensing is out, but maybe some materials change their index of refraction under charge?
  • If you want to impress me come up with a way for access to be provided via your household wiring.

    In fact if all communication could be done this way then all you would need to do is plug the machine in. Don't hook the monitor to the box, just plug it in. Need access for an Internet Appliance, just plug it into an outlet.

    Whenever an idea comes up that obviously requires new infrastructure it bothers me. We should find ways to function within existing infrastructure. With most homes wired for electricity it would seem that this infrastructure has the greatest promise.
  • We have been using a point-to-point laser for our network connectivity between two buildings (about 1/2 mile) for about 5 months now. We have had pretty good luck with it. The major problems have been weather: on *really* foggy mornings(1/2 mile visibilty), no signal... period, end of story. If it snows... forget about it. no signal, at all. Thankfully, we have had only 1 snow day during the week. ox_man
  • The NYTimes article is not very well researched, there is another company in San Diego, that I have some experience with Lightpointe [lightpointe.com] that makes these units and has sold 400 or so. These guys target companies with multiple buildings in an office park or within a few blocks of eachother in a city. These lasers mounted on each rooftop are going to be much cheaper than tearing up the ground and laying fiber so it's almost a no brainer as far as costs go. The biggest issue with these is the weather (snow, rain, fog) but these can be accounted for with stronger lasers and shorter distances. Don't try and max out the range of these units in a city like Seattle, but in Houston or dry hot places you could push the limits of them a little more.

  • Actually, fog and stuff shouldn't interfere with lasers too much, the only thing that would really mess you up is lots of lightning or if your laser gets physically knocked off its mounting...
  • Well, you may be right that it's not very new -- several groups have been working on similar things. However, the companies you mention are fiber optic companies -- a completely different animal.

    Further, they do two different things. Global Crossing is building nation- and world-wide fiber optic networks, and selling services on them. Lucent is an equipment manufacturer and vendor for fiber optics technology.

    Neither of them has anything (well, Lucent might be researching it, but not that I've heard) to do with free-space optics which is what this article is about -- shooting lasers through the air, instead of through fiber.

    -Puk
  • While this technology may not be new, implementing it for fairly cheap and with competition may be a step in the right direction for a number of reasons.

    The competition will induce aggressive advertising strategies; getting more people and small business away from modems (those who otherwise wouldn't be swayed by the hype of only two competing 100MBs ISPs (it's two in canada)); it will allow faster communications once it is developed more (ie: transmitting varying light frequencies from the same location does not cause interference as is caused by electromagnetic waves).

    I think it will also put us closer to quantum-encryption [slashdot.org] between server and client, which will improve privacy. In the long run, I envision light-based communications will take over current wire-based technology. I think we all do [myhometechie.com].
  • "Deemed safe?" By whom?

    Let's see, on earth, sunlight is about... 1.2mW per square mm.

    Now, let's suppose it's a 5mm diameter laser beam, not unrealistic at the extremes of its range. For a 100mW beam, that's, uh, 5mW/mm^2.

    Hey, they're right! It's only 4 times more intense than sunlight! It must be safe!

    Well, that doesn't account for scattering, but intensity will be much higher near the source, as the initial diameter is often around 1mm or so, or over 100mW/mm^2 - about 75 times the sun's intensity.

    I do think it will be useful, but they'll find it destroyed by lawsuits in about a week if they don't take safety considerations a little more seriously.

  • The company i work for Net-Conex [net-conex.com], An ISP centrally located in Vancouver, BC.
    As Most people know, Vancouver gets a *lot* of Rain. Rain does *not* affect our lasers. The *only* thing so far that has affected them is snow. This could have also been due to these pre-release units did not have thier proper blinders on. [fsona.com]
    From what i have learned from the guys at fSONA, they actually use 4 laser beams, of which 2 can be blocked and have the laser still work. These 4 lasers are aimed into a central receiver on the other end, in the middle of the other 4 outgoing lasers. Fiber comes out the back, into either your 100baseFX or a media converter. Reliability issues are moot, when you combine these lasers with an alternate low cost (but usually slower!) solution, such as an 802.11 radio device. The lasers that we have deployed stretch over about a 800m strech.
  • >Now, let's suppose it's a 5mm diameter laser beam,

    If they're using the same design as Terabeam, the transmitter spreads the beam out to a width of over a meter (diverging lens followed by converging lens). Then the receiver focuses it back down.

    That way a bird flying through the beam simply causes a small loss of signal strength instead of the loss of a few million bits.

    Also you get improved resistance to rain. Fog is still going to cause outages, though.

    http://www.forbes.com/forbes/2000/0501/6510148a. ht ml;$sessionid$5NU5TVQAAFN4NQFIAGVSFFQ?_requestid=2 43994
  • no! oi
  • Right, but :

    Our two building stand in the heart of history center of Paris. Basically, when the laser link goes on, it was forbiden here, in France, to beam micro-waves or so. Such techno are classified as military weapons. I'm not sure if our solution was legal aniway.
    I have to say that we have got a classical spare link, but it's running at 10M. When we download at 50Ko, then the link is broken.
    Hum, I have to say that we are sort of ISP too ...
  • I have been researching "wireless" broadband issues for the past few weeks because I have been asked to help an ISP evaluate the practical application of using wireless technologies, including lasers, to bring broadband connectivity to residential customers.

    What I find is that laser and other technologies such as spread spectrum "fixed wireless" access is very limited in it's practical application.

    Focusing on the laser issue the biggest hurdle for residential application will be cost and inclement weather.

    Cost..even though the article touts that it can bring this technology to the home users at far less cost than what businesses enjoy today. I doubt that this is much more than "planned optimism" to maintain and draw finacial support for thier business.

    I am excited about newer technologies, (this one isn't as new as they make it out to be) but I am also aware from my research that this type of connectivity will be better suited to businesses in spacific localized areas. Actually, I think it will be better utilized in a "campus" environment. Where connectivity between buildings would be in order.

    But to infer that bringing broadband to the masses via this technology is, at this point, pissing in the wind.

    Maybe in dry climates where the topography is flat and little or no smog or fog exists this could be done as they describe. But then you'll still have to have the target customer within "range" of your laser.

    There are a lot of articles about wireless in general, some even get into laser optics too.

    A few places to start looking are:

    http://www.wireless-communication.org/
    http://lw.pennnet.com/home.cfm
    http://www.broadband-guide.com/

    I have accumulated about 50 boomarks on wireless broadband and everyone of them praise the idea (as they should) but give a clear picture that this market will be stormed by large companies and especially telcos. But with all the hoopla and interest this technology is still in it's infancy. It won't be ready for prime time by next year.

    Cheers,
  • you've forgotten 2 major points:-

    1. Electron flow is not the same as current flow. The electricity will still travel at normal speed.
    2. Electron flow and current flow are in opposite directions.



    ---
  • > In my opinion the chance of a very small laser beam being hit by a rain drop are very small.

    Well, around where i live it's not uncommon that it rains enough that i can't see stuff a mile a way. What is the odds that a laser would traverse the same distance unchanged...

    /J
  • by Conch ( 52381 ) on Tuesday February 27, 2001 @02:36AM (#399331) Homepage
    How will it affect surrounding wildlife to have lasers beamed through the air every which way? Will birds have to worry about being cooked as they fly?

    Ok, risking to be troll I have to say, Read the fucking article!

    -- "There are no fried pigeons or blinded pedestrians," Mr. Redgrave asserts.
    The lasers are limited to 100 milliwats, compared to up to 500 milliwats used by the military, and have been deemed eye-safe."You can do more damage by looking directly at the sun than by looking at one of these things," he says.

    The lasers have to meet public safety standards for electro-magnetic fields and power level restrictions set by the European Commission.
    --
  • by Anonymous Coward on Tuesday February 27, 2001 @02:43AM (#399332)
    Oh, that's a shame. Living in London, I think it would be a great idea to crank the power up a wee bit, just enough to take out a pigeon. I guess that would give a whole new meaning to the old 'ping of death'
  • In moscow, at the middle of 80th laser analogue link was used for phone links between high houses.

    www.infrared.ru sells 100Mbit link (transparent for fast ethernet) for $4500 for both sides.

    Homemade systems, based on laser guide (115 Kbit null-modem link) is selling on radio bazar for handreds $

    That is not a news!!!
  • OK - so there are difficulties involved in laser-through-air, but don't write the idea off because of that.

    These problems (shimmer due to convection-induced air movement, beam occlusion due to raindrops, etc) can be addressed by future enhancements.

    For example, off the top of my head, both the above problems could be addressed by using a simple transparent carrier medium for the laser. It doesn't have to be anything fancy to deflect convection current and water - heck, glass would do.

    Granted glass would be brittle, so you might want to encase it in something else. You would also have the problem of suspending the carrier medium, so you might want to bury the result out of harm's way.

    Oh wait...
  • Actually, I remember reading something in an artical several months ago about laser redundancy. So this really isn't knew at all.
  • "You can do more damage by looking directly at the sun than by looking at one of these things,"

    On the other hand people know not to look at the sun, (a) they have been tought not too as a child, (b) it hurts when they do it. These things apparently arn't visable, so you might do it without knowing it, if the emitter is sufficently intresting looking...

    (no, I don't think it is a huge threat, but I just had to point it out)

  • http://www.geocities.com/SiliconValley/Lakes/7156/ laser.htm [geocities.com]

    With a couple laser pointers and a few bucks worth of parts, you too can build your own RS232 Laser Transceiver for your home laser network.
  • Infrared, not microwave. We gave them that warm fuzzy feeling
  • Bonjour, Here, in Paris, have we used such a technology for years, to build a 100Mb link between two blocks separated by streets, where it wasn't efficient to deploy cable. It works 24-24 7-7 !!!! No matters it's raining nor shiting something ! A group of 3 triangulated laser beams is hard enough to interrupt, also when this is a bird that land on the laser-head. Only one artefac : When temperature goes too high, you have to fine aim it, or you break the link. Voila.
  • Nice post, but use your own uid next time Mike ;)
  • Yeah. 1 meter at the target area. So? What if you're standing in a pre-target zone where the beam is smaller? That's a slightly more likely occurance. I really don't think it's unsafe if done properly, but I also doubt that they're thinking carefully about the installation technician skills and whatnot. And that's a serious issue.

    Right now, I'm working on installing a particular type of fiber loop, and the 100mW transmitter diodes are in housings of 24 each. The not-in-use ports must be be capped, as every 22 minutes comes a self-diagnostic test. It's nearly impossible to get ALL of the technicians to check port capping. They don't care. Guess who got a zap in the eye from a misaligned and uncapped port? Which was focussed nicely by my glasses. Unpleasant and not permanent, but the point is, people find a way of sticking their face in front at inappropriate distances, even those who should know better. The design should account for that. Theirs doesn't.

  • "You can do more damage by looking directly at the sun than by looking at one of these things," he says.

    Well that's reassuring. Looking at the sun will damage your eyesight but this will damage your eyesight slightly less? I'm sure they are safe but that is an awful placation.

    Phillip.
  • Whoa! This may well be the first first post by a someone who has a girlfriend!
    --
  • Ehhh, in this case they're moving through air, not fiber. It's kinda the whole point.
    --
  • Heat is. Look over a burning fire, over a radiator.. what you see is that air is being warmed up and because of that, it diverges the light.
    So does rain, but in a much more gentle way. A drop of rain is small compared to a vast area of land that's being warmed up.
  • by mindstrm ( 20013 ) on Tuesday February 27, 2001 @02:56AM (#399346)
    This tech has been around for several years now.

    The only difference now is it's significantly cheaper than it used to be, so you can build redundant links in through different paths.

    Laser works well, for lower bandwidth, RF works well, but in the end, both are more prone to outage than fiber/cable, so if you can build proper redundant/meshed networks, you can approach the same reliability.

If bankers can count, how come they have eight windows and only four tellers?

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