The
Picometer Ellipsometer uses the configuration
PBMSA (PolariserBirefringence ModulatorSampleAnalyser).
The output from the two signal channels
are directly related to Re(r) and Im(r),
where r is the fundamental quantity of ellipsometry,
being the ratio of the amplitude reflectivities
r = rp/rs. Traditionally this ratio is often
written
r = tan exp^{i}
so
that
Re(r) = tan cos
Im(r) = tan sin
The
parameter r is a much more direct representation
of the ellipsometry signal than the ellipsometric
angles and , which makes results more
accessible to interpretation. However, since
the Picometer measures both Re(r) and Im(r)
simultaneously, the data can always be converted
to the traditional notation using and
.
Due
to the modular design of the Picometer Ellipsometer,
the default PBMSA configuration can be
easily configured for many other optical
measurements such as measurements of reflectivity,
transmission, birefringence, dichroism etc.
