Dear All,

Generally a white LED is some coloured LED with a phosporescent coating that gives it a whitish glow but if you look at the spectrum it is normally heavy in one wavelength with a dispersion over the other wavelengths.

I'm working on a telecine style application, and we are looking for something that might have a similar spectrum as a xenon bulb, except without having to use a xenon bulb.

Does anyone know of any 'even spectrum' white light sources that might be as energy efficient as LEDs which are capable of being pulsed very fast (i.e. < 20 us).

Cheers,

James

 

All I'm coming up with is that a xenon source is A) excellent in spectrum, and B) might be impossible to match. I have found some graphs that demonstrate the problem. The first 2 are xenon and the third is an alleged white LED.

 

Thanks mate. Similar findings as myself. Luminous LEDs change the spectrum of white LED a bit but only shift the problem to red instead of blue.

 

What about using independent red, green, and blue LEDs? I know they can be mixed to vary the visible light, but I don't know what effect, if any, it has on the measured spectrum.

 

The graph of the spectral output of 3 different color LEDs (red, blue, green) is 3 lumps.
It looks pretty good to humans, but it sucks badly at being used for photometrics.

 

I don't believe it is available in LED form yet. At least not inexpensively.

The most energy efficient system in use for stage lighting and camera spotlighting is fluorescent. It has a very even spread spectrum.

Google......

 

What about using independent red, green, and blue LEDs? I know they can be mixed to vary the visible light, but I don't know what effect, if any, it has on the measured spectrum.

This is what we do but as others have stated it's not great for photometry or full spectrum imaging.

As you have touched on though, and we actually just brain stormed today so good on ye for the idea, we might be able to use different types of LEDs to try and get a broader part of the spectrum! i.e. Royal blue and blue mixed could result in quite a nice outcome.

It's just not fun having to go the xenon approach, and we are focused on low cost and simple.

Thanks for the responses.