I can decrease spacing to 0.000000001 or increase the count value. But no matter
how I construct the reflector, it doesn't reflect light if the light source is
placed at his axis or very near it.
Furthermore, if I use a plane instead of media the problem remains.
What draws my attention is that with this geometry for the scene, the number of
photons shot is always 5 despite the value of spacing or count.
