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Thread: Color change due to hot leds/dies? (tri-led 20mm lenses)

  1. #1
    Unenlightened M79's Avatar
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    Default Color change due to hot leds/dies? (tri-led 20mm lenses)

    Hi,

    this is my first post! I`ve recently bought tri led deep (665nm) red luxeons (one of the most efficient). The die turns green after quite short time and I think the color of the light changes slightly, especially in the center and right to leds I see green. I`m pretty sure about the die color and not so sure about the light color change; I feel a bit blinded after looking at die core (of course not directly).
    I think it may be due to die temperature, although radiator is cool.
    This issue goes even bigger if I use 20mm triled lenses (carclo). The dies go green in a short moment. Im not sure, are the dies maybe getting to hot? The color of light with lenses is not bad, the red is more concentrated, but it`s possible that I see some green.
    I`m driving the leds with safe 500mA.

    Could someone of you guys (and girls) tell me if this is normal? I would like to run them at nice deep red.

  2. #2
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    Default Re: Color change due to hot leds/dies? (tri-led 20mm lenses)

    Basic test: how hot is the LED? If you're running the LEDs at 500 mA (I'm assuming this is in series) then you're putting ~5 watts through it. A cool heatsink might mean that it's working well, but if you have a bad thermal pathway from the LED to the heatsink then the heatsink will also remain cool since not much heat is being transferred to it in the first place.
    Finning does help dissipate heat. This is why the fins are removed before cooking fish. Otherwise it will throw off the heat and not reach the proper cooking temperature. --Duglite

  3. #3

    Default Re: Color change due to hot leds/dies? (tri-led 20mm lenses)

    Deep or "super" red Osram LED's always appear to color shift on me, but they shift toward orange. If you leave the room and allow your eyes to readjust, does it still look green when you return?

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    Flashaholic* bshanahan14rulz's Avatar
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    Default Re: Color change due to hot leds/dies? (tri-led 20mm lenses)

    What did you use to attach it to the heatsink?

    I'm kind of siding with Mike S, I think your eyes may be playing tricks on you.

  5. #5

    Default Re: Color change due to hot leds/dies? (tri-led 20mm lenses)

    Is it possible that the extremely bright red die is burning an image into your vision? This will cause you to see green remnants in your vision for a short period of time. Sorry for my lack of a more technical description.

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    Flashaholic anuragwap's Avatar
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    Default Re: Color change due to hot leds/dies? (tri-led 20mm lenses)

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    Last edited by anuragwap; 11-05-2012 at 05:31 PM.

  7. #7

    Default Re: Color change due to hot leds/dies? (tri-led 20mm lenses)

    Quote Originally Posted by anuragwap View Post

    @Mike S which osram leds were you using? They have 3 kinds of red: plain 'red' 625nm, 'super-red' 630 or 633nm, and 'hyper-red' 645nm
    The super red 633nm Power TopLED. It looks red at first, but maybe 30 seconds later they'll appear more orange than red. Even the light bouncing off the walls looks orange.

    A 625nm red/orange LED doesn't have that effect on me. When placed side by side to the 633nm model, the red/orange LED appears almost pure orange in comparison. It's strange because 625nm to 633nm doesn't sound like a big jump, but it definitely has some sort of effect on my eye sight.

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    Flashaholic anuragwap's Avatar
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    Default Re: Color change due to hot leds/dies? (tri-led 20mm lenses)

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    Last edited by anuragwap; 11-05-2012 at 05:31 PM.

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    Flashaholic* bshanahan14rulz's Avatar
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    Default Re: Color change due to hot leds/dies? (tri-led 20mm lenses)

    Quote Originally Posted by anuragwap View Post
    Just like if you consume enough of the best food/drink it starts to taste bad. (The only exception I've seen to this is royal blue.)
    Yeah, I've tried cobalt blue, and it starts tasting stale if you eat too much. Prussian blue is a bit more palatable, and the flavor doesn't seem to change too much. I will have to try this royal blue sometime.
    (This thread was getting too serious...)

    I've been longing after a 635nm laser. The lower wavelength means higher visibility than standard ~660nm red lasers, assuming the same power output and density.

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    Flashaholic anuragwap's Avatar
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    Default Re: Color change due to hot leds/dies? (tri-led 20mm lenses)

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    Last edited by anuragwap; 11-05-2012 at 05:30 PM.

  11. #11
    Unenlightened M79's Avatar
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    Default Re: Color change due to hot leds/dies? (tri-led 20mm lenses)

    Hi guys again,

    thanks for all the informative comments I was blinded by the light, no green after longer time with me in the other room Led triple is properly fitted to the radiator. That`s same simple and crazy, because I was so sure, that I see green and didnt notice that it might be eyes issue.

  12. #12

    Default Re: Color change due to hot leds/dies? (tri-led 20mm lenses)

    I have noticed the effect with growlights 2 minutes of close proximity to Magenta and all you see is green

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