Recall that the ``Lab Frame'' is defined such that the incident radiation
is propagating along the 
axis.
DDSCAT.5a allows the user to specify a general elliptical polarization
for the incident radiation, by specifying the (complex) polarization
vector 
.
The orthonormal polarization state
is
generated automatically if ddscat.par specifies IORTH=2.
For incident linear polarization, one can simply set
by specifying (0,0) (1,0) (0,0) in ddscat.par;
then 
For polarization mode to correspond to right-handed
circular polarization, set 
by specifying
(0,0) (1,0) (0,1) in ddscat.par (DDSCAT.5a automatically
takes care of the normalization of ); then
, corresponding to left-handed
circular polarization.