Reply To: UV/Visible light meter


The Environmental Monitor Type 765 monitors all four parameters, (µW/lumen)/ Visible light / RH/ Temp, but does not have remote downloading capability.  

I wonder why your client needs logging of µW/lumen over an extended period of time?  The beauty of the µW/lumen metric is that if an initial UV reading is reasonably low (>75 µW/lumen is a common museum standard) then measuring visible light (illuminance) alone might be enough to manage risk.  In other words,  the quantity of UV is (reduced) in proportion to illuminance.  This means if you are meeting your illuminance targets (typically 50-200lux — depending on the material) then UV might not need to be measured over time, at least for filtered artificial lighting sources like HID and florescent.   Is there a concern that the filters won’t hold up or won’t be replaced? 

I am less familiar with the variations of UV output in filtered daylight over time;  if anyone has experience with measuring UV in daylight I would be grateful for more information.      I have an Elsec Environmental Monitor Type 765 as well as a spectrometer that measures radiation down to 200nm and I will run some daylight tests if I can find the time.

Lastly, I am unclear what the Elsec and other environmental meters are exactly measuring when it comes to UV?  I am sure they do a good job of determining if UV is a problem, but I am skeptical if the numeric values are particularly accurate.  According to the Elsec’s cut sheet, their meter measures UV between 300 and 400 nm with an accuracy of 15%.  If anyone has more information about this, I would be grateful to know more about how these meters actually measure and what bandwidths of particular lighting sources I need to be concerned about.