Re: New spectral tool - transmissive lightsource
Re: New spectral tool - transmissive lightsource
- Subject: Re: New spectral tool - transmissive lightsource
- From: Graeme Gill <email@hidden>
- Date: Mon, 02 Mar 2009 12:14:06 +1100
Roger wrote:
light temperature constant. That's a whole speciality in itself. Maybe there
will be help soon from some new LED gizmo? It's surprising the slew of LED
applications, we're just beginning to scratch the surface.
LED's aren't a very good source in many ways though. Typical white LEDs have
quite a dip between where the phosphor stops and the blue peak of the LED itself,
and (as is typical of LEDs) the peak drops off very steeply above that.
LED's output also varies with temperature, so you either need to
stabilize the temperature with complicated thermal gear, or compensate
the reading somehow (which is what the ColorMunki does - it measures
the voltage drop across the LED, which varies proportionally to temperature,
and during its calibration creates a model of the LED output verses voltage
drop as it turns the LED on for five seconds. It then interpolates
it's model of the LED output vs. voltage drop for each reading).
Using many LED's of different overlapping wavelengths is a possibility,
but optically combining a dozen LED's output is a challenge, the resulting
spectrum is kind of bumpy, and the thermal issues remain. Not only
does the output change with temperature, but the wavelength shifts
slightly as well. I'm sure it's doable if you go to enough trouble,
but it's not going to be cheap.
Graeme Gill.
_______________________________________________
Do not post admin requests to the list. They will be ignored.
Colorsync-users mailing list (email@hidden)
Help/Unsubscribe/Update your Subscription:
This email sent to email@hidden