IR from a LuxV?

It's friday for a 3-day weekend and here I sit, feeling no pain, way too early. /ubbthreads/images/graemlins/grin.gif Out of curiosity/boredom, I picked up one of my SF E2L Outdoorsman "error" lights and shined it in my ear to see if my retina could register it from behind. (It is a 5W LS, direct driven with 2 R123's.) My retinas failed to register, (I tried both ears) but I definately felt radiated heat! (Again both ears.) Next I tried it with my L4's. Same result, but with much less heat. I was unaware of any infrared component for LS's! Is it coming from the gold die leads from the tortured critters or?

(First person suggests I try it with the USL proto gets put on other list! /ubbthreads/images/graemlins/grin.gif )

Larry

Could it be the LED heating up the reflectors, perhaps? I'm not certain on the physics, though - bu with the way those lights get cooked out front, could you have been feeling the heat radiated from the bezel and other hot surfaces which are radiating conducted heat from the LED?

Could it be heat radiating off the bezel? As the LED's heat gets dissipated into the light's body (through whatever heatsinking those lights have - I don't have one to check), it's transmitted towards the end of the light (as well as other parts of the it), and when you put it close to your ear, you had the feeling it was the light source emitting heat? (?????) /ubbthreads/images/graemlins/icon3.gif

The effect is instant- no time for the reflector to heat-up, and is immediately gone with the release of the button! I think it's coming from the die. The die itself gets hot and most of the heat is supposed to be conducted away. I'm guessing not all.

Larry

You should try that with your USL proto. /ubbthreads/images/graemlins/wink.gif I noticed the same thing happen with mine.

I think all kinds of light carry energy; incans just happen to emit LOTS of IR which translates into lots of heat felt but the visible light also heats things up, there's just less of it and therefore is less obvious... In the case of the Luxes, there's no IR but still quite a bit of light.
That's my guess here.

***EDIT*** I didn't see the posts after greenLED's. What kungfuchicken said.

I think it is just plain inefficient energy in the form of heat following the same path as the photons.

A more sensitive area is your lips. Take any white LED 1W, 3W or 5W and shine it at your lips from a few inches away and you'll feel instant heat. Nothing is heating up.

Try a 5W Royal Blue. No infrared there either but a ton of instant heat.

Now, without the use of an LED flashlight, sip 3 generous shots of your favorite whisky within, say an hour or so. Your ears should heat up pretty good. /ubbthreads/images/graemlins/blush.gif /ubbthreads/images/graemlins/smile.gif

Absorbed light can definitely produce heat.

Think about it.

Light hits an object and is absorbed. The energy is usually converted to heat. Otherwise it is reflected or transmitted.

I wouldnt say try it with the USL proto but definately a costco HID /ubbthreads/images/graemlins/wink.gif Less actual heat so you wont have to worry about your brain ending up like the egg.

This is your brain on USL's, Any Questions?

Shane

edit: misread.

Thank you kongfu and Jar. Thinking about it with a clearer mind, they are emitting close to a watt of energy as visable photons. The absorbtion of ~half of that by my ear converts it to heat, with the associated temperature rise.

Larry

Hey, anytime Larry.

Yes. That was an interesting question, tvodrd.

Boy, I was way off.

Excellent answers kungfuchicken and Newbie.

Absorption causing energy conversion. Cool.

Hi Larry,

The other possibility is that it was a psychosomatic response.

You knew that you were turning the light on and your brain automatically associated the "light" with "heat" which caused you to actually feel it.

The phenomenon is relatively well known in the medical field. It is also used by non-contact "faith healers" to make people believe that something is happening as they wave their hands over the patient.

If you have a second person around you could test out the theory. Make sure that you can't see the light going on and off and can't hear the other person turning it on and off. Then your partner turns the light on and off while you try to determine whether it is on or off.

pb

What you could do is get a filter that doesn't pass IR light and try again...

bingo!
tried a 3d mag@1a with a lux3 and dont detect any heating.
any heat is getting soaked up by the osink.
if the luxeon was emitting enough ir to feel on any part of your body non contact it would be a sed or fed!
[ QUOTE ]
pbarrette said:
Hi Larry,

The other possibility is that it was a psychosomatic response.

You knew that you were turning the light on and your brain automatically associated the "light" with "heat" which caused you to actually feel it.

The phenomenon is relatively well known in the medical field. It is also used by non-contact "faith healers" to make people believe that something is happening as they wave their hands over the patient.

If you have a second person around you could test out the theory. Make sure that you can't see the light going on and off and can't hear the other person turning it on and off. Then your partner turns the light on and off while you try to determine whether it is on or off.

pb

[/ QUOTE ]

Yup, absorbed light will produce heat. A 200 lumen R/O LuxIII won't make you feel much heat as the red light tends to pass through your skin.

But a LuxV Royal Blue will make your skin feel warm as the blue doesn't pass through and is absorbed more..

[ QUOTE ]
IsaacHayes said:
Yup, absorbed light will produce heat. A 200 lumen R/O LuxIII won't make you feel much heat as the red light tends to pass through your skin.

But a LuxV Royal Blue will make your skin feel warm as the blue doesn't pass through and is absorbed more..

[/ QUOTE ]

Thanks, IsaacHayes. I was wondering about that.

Now I want an R/O for exploratory purposes. I had a bump on my wrist last year and they thought it was an aneurism caused by an accidental bump. I went home and pressed a white LED light against the skin next to it. It lit up. If it were blood it would be dark. It was just some fluid caused by over exerting the wrist. The box of VIOXX is still in the cabinet to remind me to think for myself. A 3W R/O would have been useful.

It is a common misconception that only IR light heats up the surface it falls onto. If you have a surface that absorbs all light falling onto it, it makes abolutely no difference in heating if the light is IR, Red, Blue, Green, UV or something else.

I used to wonder about that phenomenon when a light beam would move across my (closed) eyes - they would perceive heat. I later decided that wasn't the case when I couldn't replicate the phenomenon with any other body part.

I'm not going to suggest that absorbed visible radiation doesn't produce heat - just that the eyes will react to direct light sources with the perception of heat to get you to look away. The back of my hand, my arm, the back of my neck not being as good at detecting light as the eye, I felt nothing.

I've just repeated the experiment with my ear and I also feel heat. Perhaps the eye and ear are both better heat detectors than the rest of the body...