determines the total energy of all emitted photons and hence the
strength of the caustic effect.
Energy intensity controls
the brightness of the caustic effect. The default value is 10 000.
Values of 1 000 and lower give a very subtle effect. Values range up
to 1 000 000 at which the effect appears as a solid bright light.
Photon Energy is distance dependent and therefore larger energy
value are required to affect objects further from the light source.
Changing the energy value does not affect the rendering time
as it is the brightness of the caustic effect which is changing
rather than the photon storage calculation.