Thank you keithr. I haven't seen it, but i think liquid nitrogen is clear as water. It also boils at -196C. It can be had from various medical and industrial sources if you bring a regular thermos (don't close the thermos all shut, because the nitro will vaporize slowly (boil) and create pressure). The nitro would then be poured in a clear glass (take care with thermal tension and cracking of the glass) for the experiment. Maybe an optic or reflector could be glued to the inside of the glass. Connect an adjustable power supply, set up a lux meter and a camera as well as means of measuring electrical power to the LED, and turn up the power slowly until the led is destroyed.
(I'm waiting for my first luxeons from the sandwich shoppe, but I don't have a camera nor any luxmeter. If there is any of the leds I don't like, I'll consider doing the experiment anyway.)
I think it could be interesting to know more about how much gain there could be had from better heat management, and also it could look quite spectacular.
If what kakster says is true, and the 3 watters are specced to 3 watts, then I speculate that at least 5-6 watt should be possible for the regular 1watters in extreme cold. But I have no experience to back it up, though.
