[Radiance-general] I can't get even similar irradiance values from lamps.

[Lars O. Grobe]

Hi!

> as 0.032m is diameter, which Lars might already know.

Well, good point.... ;-)

Maybe this is of help:

http://www.uvequip.co.za/faq.htm

"Of the approximately 456 types of fluorescent lamps made all of the UV 
or Blacklight lamps make up less than 1% of the total lighting 
industries lamp production. Therefore there is not much economic 
incentive to do research to develop low UV depreciation LW phosphors and 
lamps. The typical UV depreciation of a 4W, 6W, or 8W LW lamp might be 
as much as 40% to 50% in about 2,400 hours.

UV SYSTEMS has just completed a scientific UV depreciation test using 
one TripleBright II LW LL-60-352 lamp. From this test it was determined 
that the UV output of that lamp depreciated to about 80% of initial 
output (a 20% reduction) after about 7,000 hours of use. While this was 
only a sample of one, it could be typical of all LL-60-352 lamps."

And some more tests (you can see a set-up how to determine the 
depreciation in this paper, too):

http://www.uvsystems.com/articles/Life_SW_Filters_UV_Depreciation_Lamps.pdf

CU Lars.
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