The algorithm tries to obtain the specified fluence for the laser field.
This works only in conjunction with either the WG05 or the straight iteration scheme.
If this variable is not present in the input file, by default the code will not
attempt a fixed-fluence QOCT run. The same holds if the value given to this
variable is exactly zero.
If this variable is given a negative value, then the target fluence will be that of
the initial laser pulse given as guess in the input file. Note, however, that
first the code applies the envelope provided by the OCTLaserEnvelope input
option, and afterwards it calculates the fluence.