If you are modelling illuminating effect, most likely you will model the system under non-sequential mode and you could look up LeYI<a@n@$
]>[0DX]j
Source Diode and Source Gaussian 3g5D[>J'
h]&o)%{4
to check if these two sources types support your source behavior. If they do then it should serve an good approximation for your light source.