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Old 04-04-2007, 10:04 AM   #11
SigmaPi
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Join Date: Oct 2006
Location: CO
Posts: 56
Quote:
Originally Posted by z12358
Sigma, I'm not familiar with LED tailights but couldn't they be radiating energy in the LIDAR (IR) spectrum, as well?
Z.
I guess anything is possible. Typical specs for LED modules in brake lights are around 640 nanometers. Relative intensity peaks at that wavelength but a typical brakelight projects it's light over a range i.e. 620 to 670 nanometers. With that being said, it may produce some IR light. The IR spectrum is huge and starts at about 750 nm all the way out to 1mm. Some laser detector's may have an IR detection range that is from 750 to 905. I don't think this is probable though. Two issues are at hand, cost and appearance of crappy quality. If a detector company chose to employ a photodiode that detected over that wide a range it would be costly. A photodiode that has the ability to view wavelengths over that much range are expensive. I am not sure why a company would want to do this because it would obviously induce more false positives, therefore giving the user the impression it sucks. I am assuming BEL, Cobra etc all use a very specific photodiode with a range from 850 to 910nm. It's cheaper and is made to look for the only wavelength police LIDAR guns utilize today. Long story short, I don't think LED taillights would do it, but I have been wrong before. Something more plausible is the detector may be picking up natural IR light.

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