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Laser Umbrella

I'm zinging in the rain
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This hi-tech precipitation interceptor looks like a shaft with a handle but is loaded with star wars capability. At the top is a miniature radar that locates rain, snow or hail within a one meter radius hemisphere above it. High-speed processing allows a built-in laser to lock on and vaporize each falling drop/flake/stone in turn. All that is seen above the dry user, in addition to the light show, is a cloud of water vapor.

For safety reasons, objects larger than 1 cm are not targeted. The laser umbrella can also be advantageous in the fly-infested outback.

FarmerJohn, Apr 23 2002

Almost like this (annos) http://www.halfbake...for_20Mr_2e_20Winky
[lubbit, Apr 23 2002, last modified Oct 05 2004]

I have the same idea. http://www.halfbake...0raindrop_20blaster
ultrasound instead of laser. Less likely to blind someone [bing, Apr 23 2002, last modified Oct 05 2004]

[link]






       I wonder...what about bullets? I also wonder about power requirements; killing flies is one thing, vaporising hailstones is another ball of ice. I'm too lazy right now to do the maths, though.
Dog Ed, Apr 23 2002
  

       'All that is seen above the user is a cloud of water vapour'... wouldn't that be rather like walking around under a raincloud all day? I'm sure it would affect one's mood. Perhaps there could be a secondary non-laser light source which could create a halo or hemisphere of golden light underneath this dull cloud. Otherwise you might end up with cholesterol problems worse than just having got wet or having to have had to hold up a brolly. ((body can metabolise cholesterol better in summer when more sunlight assists production of Vit. D))..
sappho, Apr 23 2002
  

       Not necessary. Since every cloud has a silver lining, the reflected light show would keep your mood and vitamin D production higher than the losers hunkering under their old-fashioned umbrellas.
FarmerJohn, Apr 23 2002
  

       What about a GPS-based system that compares global location with local weather reports, and then uses high powered satellite-based lasers to modify the local weather.
RayfordSteele, Apr 24 2002
  

       Croissant just for the "I'm zinging in the rain"...made me choke on my veggies. However, if it only targets objects smaller than 1 cm, does that mean one is walking along, happy as can be, in a thunderstorm--until--BLAM!... one finds oneself hit by 1.1cm hail? Perhaps some system that devotes the same energy to those as is used to eradicate the smaller ones, thereby reducing larger ones in size... ?
Urania, Apr 24 2002
  

       Ha! Great idea for the bug-zapping angle. This could be an early application of nano-technology, maybe, if the works need to be that small--I don't know. But I really like the idea of a laser defense against biting flies. Put it on the top of a ball cap. Limit the range and intensity so that it does no harm to people or pets, but wrecks havoc on flies. Runs on batteries. This would be a precursor to space (small) junk detection and destruction for an advanced space habitat.
entremanure, Apr 25 2002
  

       I was about to post something similarish. A slightly more elegant solution would be not to try to vapourize each droplet completely. Instead, detect the droplets when they are about 4m above you, then zap them with a tight beam on one side. Vapourizing only a tiny fraction of the water will be sufficient to impart a sideways acceleration, allowing it to fall slightly to one side of you.   

       By my reckoning, the average raindrop is maybe 10ul in volume, and perhaps 100 drops per second fall, or about 1ml/s. To vapourize this completely needs a 2kW laser (with no losses). By vapourizing only 1 microlitre or so of each drop, this is reduced to a much more managaeable 200W.
MaxwellBuchanan, Mar 19 2008
  

       //By my reckoning, the average raindrop is maybe 10ul in volume//   

       Really?
I reckon they vary in size between about 0.1 mm (very fine) and 5 mm (fairly large) diameter. Or 0.0005 to 0.0025 m radius.
  

       If we assume they're spherical they must have a volume of 5.2e-10 to 6.5e-8 metres cubed.
Multiply by 1e9 to get ul and we have a range of 0.5 ul to 65 ul.
  

       So... um, as you were.
Loris, Mar 05 2013
  
      
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