hotfoot
Flashlight Enthusiast
And I'm not talking about IR LEDs either folks.
I was playing around with a 5W blue luxeon mod and for the heckuva it, shone it point-blank onto my lips. The flashlight made no physical contact with my skin, but I *swear* I could feel warmth radiating out from the flashlight and onto my lips.
Next, I took my probe thermometer and did a similar experiment. After switching on the thermometer and letting it stabilize to room temp, I took the same blue 5W LS mod and shone it on the probe, again without making any physical contact between probe and the flashlight or me (and my breath..etc..etc). The temperature shot up by at least 3 degrees C almost immediately!
In both cases, I was using an NX05 optic and at the time of both experiments, a stone-cold flashlight was used (ie. LED was allowed to cool down).
Lumileds and other LED manufacturers have been touting the fact the radiant heat is not emitted when using LEDs, but my 2 experiments above seem to indicate otherwise! This raises a few questions:
- What is the source of this radiant heat? If LEDs are fairly monochromatic and I was using a deep-blue LED, surely there could not have been any infra-red, right? Or was the near-UV energy strong enough to cause similar heating phenomena?
(BTW, I tried the experiments with overdriven white 1W LEDs with similar, albeit less dramatic, results.)
- If we start using clusters of high-powered LEDs (eg. a cluster of 6x5W LSs), would radiant heat once again become a problem, akin to that faced by users of halogen lamps?
Anybody have any ideas to this? I'm stumped...
I was playing around with a 5W blue luxeon mod and for the heckuva it, shone it point-blank onto my lips. The flashlight made no physical contact with my skin, but I *swear* I could feel warmth radiating out from the flashlight and onto my lips.
Next, I took my probe thermometer and did a similar experiment. After switching on the thermometer and letting it stabilize to room temp, I took the same blue 5W LS mod and shone it on the probe, again without making any physical contact between probe and the flashlight or me (and my breath..etc..etc). The temperature shot up by at least 3 degrees C almost immediately!
In both cases, I was using an NX05 optic and at the time of both experiments, a stone-cold flashlight was used (ie. LED was allowed to cool down).
Lumileds and other LED manufacturers have been touting the fact the radiant heat is not emitted when using LEDs, but my 2 experiments above seem to indicate otherwise! This raises a few questions:
- What is the source of this radiant heat? If LEDs are fairly monochromatic and I was using a deep-blue LED, surely there could not have been any infra-red, right? Or was the near-UV energy strong enough to cause similar heating phenomena?
(BTW, I tried the experiments with overdriven white 1W LEDs with similar, albeit less dramatic, results.)
- If we start using clusters of high-powered LEDs (eg. a cluster of 6x5W LSs), would radiant heat once again become a problem, akin to that faced by users of halogen lamps?
Anybody have any ideas to this? I'm stumped...