John:
As the "wattage" (or "voltage") increases, we do not increase the strength of any of the UVR "photons" (packets of energy); rather, what we do is to create more photons.
Although it is not quite the same, you can "visualize" this phenomenon by turning up the rheostat on your dining room ceiling light. As the "intensity" of the light increases (making it easier to see), the "change" is in the number of photons, not increasing the "strength" of the existing photons.
A 365 nm "photon" has a quantitatable "strength" that doesn't change as the power is increased. FYI, we "weight" a 280 - 302 nm "photon" 2000 times "heavier" ("stronger") than we do a 365 nm photon. That is because the 280 - 320 nm "photons" are more energetic and, thus, have more sunburning power.
What we must learn more about is the "tanning power" of our
lamps which means that we have to "weight" the longer wavelengths "heavier" ("stronger") than they are in the EAS (erythemal action spectrum). This is what we have done with our TAS (tanning action spectrum) and what Wolff is looking at with their TAS.
Steve is correct when he says the best that can be done today is to use the MED/hour meter to evaluate the EAS and the A & B meter to "estimate" the TAS.
Hope this helps.
Don
PS: IMHO, Cosmedico is wrong! Their calculations "devalue" the efficiency of THEIR sunlamps! Does is make sense that we "lose" 60% of the output? If we did, our electrical costs would skyrocket!