...do CFL's radiate IR?.....and is this why CFLs don't need aluminium heatsinks.?
Or are they not affected as much by operation at high temperatures? In this case we're talking about the light emitting element itself, not the electronics.
Clearly incandescent bulbs are happy to operate at temperature and don't have electronics.
Fluorescent bulbs - what happens if they heat up? How much surface area do they have for a given power?
LEDs - cf fluorescent bulbs.
What percentage of incandescent light is IR?
I presume that since leds don't give off IR, then leds can't be seen by the police "eye in the sky" spy helicopters when at night-time?
You assume that the police don't have the ability to see normal light. I would suggest they do.
Also, the article you kindly link to has info on LED lifetime....however, would you agree that if a LED lightbulb contains electrolytic capacitors in its driver circuitry, then the lifetime of that led product is as for the lifetime of the electrolytic capacitor, and has nothing to do with the lifetime of the LEDs?
The product lifetime is determined by the shortest lifetime of any of its components. I guess there is no point in doing stuff that stretches the lifetime of the LEDs from 25,000 to 50,000 hours if another component will only last 10,000 hours.
However, it is worthwhile keeping the LEDs cooler if that also stretches the life of the capacitor from 10,000 to 17,000 hours.
Note that whilst there is a strong business argument that the bulbs should not fail early in their life, suspect that there is also a good business argument not to make them last too long either.