Does Combined Luminosity of LEDs Add Up?

[Euan12345]

TL;DR

Say you had a green and red LED, both with a luminosity of 2 W would the combined luminosity be 4 W or still 2 W?

Say you had a green and red LED, both with a luminosity of 2 W would the combined luminosity be 4 W or still 2 W?

 

[Andy Resnick]

Summary:: Say you had a green and red LED, both with a luminosity of 2 W would the combined luminosity be 4 W or still 2 W?

Say you had a green and red LED, both with a luminosity of 2 W would the combined luminosity be 4 W or still 2 W?

On the face of it, I would say 'yes', since luminosity is a measure of total output power. However, your sources aren't isotropic emitters: the radiance of these sources strongly depend on the angle with respect to each emitter's surface normal.

What that means is that if the sources are not facing the same direction, the received power from each source is likely different.