I have an omnidirectional IR emitter that illuminates a "room". In that room I have say a 10" x 10" diffusive reflective surface that's at distance D1 from the emitter and a sensor at distance D2 from the reflective surface. The reflective surface is diffusive and I'd like to have an estimate of the power density contribution of the reflective surface alone at sensor.
If I count omnidirectional propagation to the target, then again from the target to the sensor, then path loss gets frighteningly huge. But this isn't representative of reality and I miss wall reflection (both paths) and I don't even a rough way to factor that in.
Any hint or pointer?