Coloured Luxeons

A while a go someone came up with colour sheets to degreenify too green luxeons. This is good idea as it 'tunes' the tint of the luxeon. I am wondering if there are any colour filter that can completely filter out a red luxeon to a white luxeon?

There is a red luxeon has an output of 40 lumens, if waste is 50% we are still left with 20 lumens. Ok.. I know what I am talking about, if this works lumileds would have done it. But, is this practical? does it work at all?

White - 22 Lumens
Cyan - 30 Lumens
Amber - 36 Lumens
Red - 40 Lumens
Red Org - 55 Lumens

Vince.

i dont think thats going to work. It works with white LS's because they are a mixture of blue(die) and phosphor(green). If you filtered the red out of red luxeons, you'd have...well, no light.

No. White light is the sum of all visible light frequencies. Red is only a single frequency (ok, a narrow range). Color filters subtract from a projected light. If you subtract anything from a red LED you'll just get dimmer output, i.e., less red. To produce white light you need to add multiple colors together, and gel filters can only subtract.

Thanks for making it clear for me. So it means that each different colour Leds has different wavelength that can't be converted to another wavelength ?

Vince.

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nukiez said:
Thanks for making it clear for me. So it means that each different colour Leds has different wavelength that can't be converted to another wavelength ?

Vince.

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Correct, not without special optical tricks at least. (Phosphors, nonlinear optics, etc.)

Typical things that CAN be done, although not always efficiently:
Double the frequency (halve the WL) - This relies on special crystals that have a nonlinear response. Frequency doubling via nonlinear optics is the way DPSS green lasers work.

Absorb and reradiate the light - This will always result in light with a lower energy per photon (lower frequency/longer wavelength.) Typically done with phosphors. This is how white LEDs work - A phosphor coating is placed on top of a blue LED, which absorbs some of the blue light and reradiates it as a broadband yellowish-green spectrum. This yellowish-green light mixed with the unabsorbed blue looks white. This is why white LEDs can vary so much in color - "greenies" have too much phosphor, "bluish" LEDs have too little. Since the phosphor's absorption/reradiation response is somewhat nonlinear, it is possible to correct the color balance somewhat by over/underdriving the LED. Using a similar trick on a red LED would only result in a dimmer red LED (at least to the eye - The LED would also reradiate IR light.)

Another variant of the absorption/reradiation idea is also used in DPSS green lasers. IIRC, one crystal in the laser is pumped at near-IR, which lases at a longer IR wavelength. It is this longer wavelength that is then halved in a nonlinear crystal to become green.