Hi, I'm new here. Been surfing around SF.net, but just bumped into this forum, and I'll hope to be gaining alot from my time here. I'm majoring in Electrical and Electronic Engineering in college. Nice to meet you all ^_^
As far as I know, you can't measure an "absolute intensity" of light. There can be an absolute absence of light (i.e. not even 1 photon), but where would one set a limit for a max value? And when our units like Watts/area comes into play, there is possibly no other way but to calibrate it with a known reference. You can probably derive a way to do so using fundamental physics with say a 60W light bulb. Usually measurements are only important in a relative sense anyway.