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Is there a LED with adjustable Wavelength and color? Answered

I just need a LED that can give me desired color and wavelength (in nm). I just googled but found nothing. Hope I will find one.
Thanks in advance.



2 years ago

Actually you can alter the wavelength of most LEDs with temperature.

There do exist RGB LEDs, consisting of one red LED, one green LED, one blue LED, all in the same package. Sending different amounts of current to each of these three LEDs, allows it to display different colors, or perhaps the illusion of different colors. In truth it just emits varying amounts of exactly three colors of light.

This instructable,


shows a picture of this kind of LED, new with its four unbent leads, in the picture for Step 1. In other pictures in this 'ible, you can see this LED "in action" displaying different colors.

Anyway, this sort of RGB magic is capable of fooling the human eye, and also digital cameras, but if you fed the light output from one of these RGB LEDs to a spectrometer, you'd get a plot with three peaks, with the amplitude of those peaks corresponding to the amounts of red, green, and blue light.

In contrast, a spectrogram from a true monochromatic light source, like from a yellow LED, would have just one peak.

Curiously, the human eye (and also cameras made for the same) cannot tell the difference, e.g. between a yellow monochromatic light source, and a mixed light source of just the right amounts of red and green.

Not sure what your application is, but if just for light for humans to see, then a RGB LED is probably good enough.

No, the way normal leds work forbids it. White leds use phosphors to emit light, which is filterable to soms extent. The link shown combines 8 discrete colours.


2 years ago