  In the past decade, several neutron reflectometry methods for determining the
modulus and phase of the complex reflection coefficient of an unknown
multilayer thin film have been worked out among which the method of variation
of surroundings and reference layers are of highest interest. These methods
were later modified for measurement of the polarization of the reflected beam
instead of the measurement of the intensities. In their new architecture, these
methods not only suffered from the necessity of change of experimental setup,
but also another difficulty was added to their experimental implementations.
This deficiency was related to the limitations of the technology of the neutron
reflectometers that could only measure the polarization of the reflected
neutrons in the same direction as the polarization of the incident beam. As the
instruments are limited, the theory has to be optimized so that the experiment
could be performed. In a recent work, we developed the method of variation of
surroundings for one directional polarization analysis. In this new work, the
method of reference layer with polarization analysis has been optimized to
determine the phase and modulus of the unknown film with measurement of the
polarization of the reflected neutrons in the same direction as the
polarization of the incident beam.
