[argyllcms] Re: Absolute light meter calibration?

  • From: Richard Kirk <richard@xxxxxxxxxxxxxxxx>
  • To: argyllcms@xxxxxxxxxxxxx
  • Date: Wed, 12 Aug 2015 20:12:32 +0100


On 12 Aug 2015, at 18:25, Marwan Daar <marwan.daar@xxxxxxxxx> wrote:

This isn't a strong suit of mine, but wouldn't you need to know the
emissivity of the filament before making these calculations? If the
emissivity is 1.0 (i.e. perfect black body), then I think you can assume that
all the power "fed" into the filament is expressed as radiant flux. But for
real objects, the emissivity is lower than 1.0, which means that not all the
absorbed power is expressed as radiant flux. At least this is my naive
understanding.

Do you accurately know the surface area of the filament? The emissivity is only
useful if you know the watts per square meter leaving the surface from the
temperature and the emitting area. In the bulb we have a certain amount of
emission which is caused by the input electrical power; but we would get just
the same from another bulb with half the emissivity and double the surface area.

I think...

Cheers.
Richard Kirk



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