Re: Request for spectral data of light sources
Re: Request for spectral data of light sources
- Subject: Re: Request for spectral data of light sources
- From: Roger Breton <email@hidden>
- Date: Sun, 14 Oct 2007 09:54:03 -0400
>> White LED = http://en.wikipedia.org/wiki/Image:White_LED.png
>
> Mmm.... There's also this other LED spectral graph on Wikipedia:
> <http://tinyurl.com/3cqwcs>
Yes, but this "LED" spectral graph shows typical LumiLEDs, the type of RGB
LEDs used in the outrageously expensive NEC LCDLED monitor. That type is
very different from white LEDs. I don't think the iSis uses a combination of
three LEDs as its source but more like one white LED.
> if pulsed-Xenon is supposed to be smooth and LED spiky, ...
>
> Marco Ugolini
My point for Xenon, Marco, is not that it is a smooth function but that it
throws a lot more UV energy onto the specimen when measuring reflectance
then a tungsten source can. Thereby exciting more fluorescence and, in the
opinion of many color scientists, correlating better with our visual
assessments when the specimen is viewed under real daylight sources. But I
don't know much about the arrangement of the LEDs inside the iSis. I gather
it uses a single UV-LED and a single white LED. No one knows at which
wavelengths this UV LED is illuminating. And no one knows the SPD of the
white LED. As users, X-rite will say that whathever arrangements they chose
in their design should be "transparent" to us, as long as readings are
comparable to those obtainable with other instruments. But we are a curious
bunch and, personnally, I'd like to know exactly what's going on inside this
instrument before I give X-rite my hard-earned dollar for an iSis.
Roger Breton
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