h a l f b a k e r yExpensive, difficult, slightly dangerous, not particularly effective... I'm on a roll.
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License tag/plate cameras are in wide use in security, toll collection and traffic infraction prevention systems. Snow can degrade performance. This device uses an energetic infrared laser device directed by some spiffy xpatch like control system to melt snow from license plates.
This system is
cost-effective when there ratio of cars to cameras is very high. When the ratio of cars to cameras is very low, consider Heated License Plates (below).
Heated License Plates
Heated_20License_20Plates
Lest we forget [husband_of_bath, Dec 08 2007]
[link]
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I could see this as a device in action movies. [+] |
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Did you think about this? OK, suppose
there are 100g of snow on the licence
plate, and suppose that you need to
melt this in half a second (as a car
drives past). |
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The latent heat of fusion of ice is about
335J per gram, so you need to deliver
about 33,500 Joules of energy in half a
second (this assumes that the snow is
already close to its melting point). This
means that you have to deliver about
67kW of heat to the licence plate. So,
you are going to be wielding a 67kW
continuous-mode laser, aimed by a
"spiffy" system, amidst moving traffic. |
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//This means that you have to deliver about 67kW of heat to the licence plate. So, you are going to be wielding a 67kW continuous-mose laser, aimed by a "spiffy" system, amidst moving traffic.// |
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Had this been a licence plate snow generator, on the other hand... |
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100 grams of snow on a license plate? I guess I wouldn't really know, as I can still wear a sweater outside, and need short sleeves on in the afternoon, but how does a tenth of a kilo get stuck on a primarily vertical surface? |
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What could possibly go wrong? |
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//100 grams of snow on a license plate?//
That's four ounces, or enough for a
modest snowball. Feel free to assume
50g, requiring only a 34kW laser. |
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Sounds like it would be easier to use a snow penetrating radar to read the shape of the number thru the snow. |
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Does everyone use raised letters on their license plates or is that just in the states? |
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Number plates in UK used to have raised characters. Now, they're smooth - black letters and numbers on a white (front) or yellow (rear) reflective surface, with a clear top layer. They're quite expensive, but we don't often need to buy them as the number stays with a car for life (unless an owner changes to a 'vanity' plate, or it's re-registered for some other reason). |
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Seeing how I dearly detest traffic cameras - I found the destroyed Gatso website amusing and disturbingly compelling - the last thing in the universe I want mounted on these things is a HEAT RAY. |
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But if I could have one on my car aimed back at the camera, that's another matter. |
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//But if I could have one on my car aimed
back at the camera, that's another
matter.// |
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The mirror isn't as fun as actually getting to aim and fire the GatsoBlaster for myself. But it is more defensible in that it is a passive device. |
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