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Laser Lighting Trial Starting in China

8/22/2017 11:01 AM EDT
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Kaitlyn
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Re: Cost?
Kaitlyn   8/25/2017 3:20:41 AM
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It is well studied but I think that there are always disadvantages ...

Jayna Sheats
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Re: Cost?
Jayna Sheats   8/23/2017 1:16:12 PM
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Thanks; shape control makes good sense.  

TanjB
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Re: Cost?
TanjB   8/23/2017 12:14:51 PM
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The article, linked in the text, about Steven DenBaars at UCSB states that efficiency is the same.  Indeed they imply using basically the same diodes but just adding the mirror edges to get a laser instead of an incoherent light, allowing them to beam it better and to operate the device at higher intensity.

For those unfamiliar, UV is used because (a) the GaN diode is the most efficient converter and (b) the UV it produces can be used to energize phosphors which will be mixed in proportions that give a visible light curve similar to black body which is important to us perceiving color reflected off objects.  This is different to a video screen which produces colors by mixing 3 pure colors directly seen.

The description of using broad panels over the ceiling or fiber optics does not require lasers - your laptop does this with LEDs and phosphors already.  So, the whole article is a bit of a muddle.  The main advantage of lasers is shape control, like in headlights.

Jayna Sheats
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Cost?
Jayna Sheats   8/23/2017 12:00:50 PM
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I am clearly missing the point: why will it be save energy?  Of course lasers produce more irradiance than LEDs, but not more photons per electron.  

On the cost side, one laser diode gives more photons per $ than many LEDs. The infrastructure for safe delivery may or may not negate that advantage.  But I can't see the energy efficiency.

Don Herres
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Interesting to chose blue light
Don Herres   8/23/2017 11:37:29 AM
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As is known by anyone looking at a blue sky, the blue light will scatter the most.  Given the persistent smog in many cities in China, this seems a strage choice compared to using infrared lasters.

Alan Patterson
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Re: What happens when it rains?
Alan Patterson   8/23/2017 2:49:13 AM
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I asked the same thing, including what happens when birds or bugs fly through the laser beams. Apparently, the trials are aimed at sorting those issues out. -- Alan Patterson

dnadler017
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What happens when it rains?
dnadler017   8/22/2017 5:38:10 PM
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Wondering about their "long distance power transmission via laser" to street lights during inclement weather - how will this work?

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