Zero-field neutron polarimetry is a technique which has recently been
developed to allow spherical polarization analysis to be carried out i
n a neutron scattering experiment. The incident beam polarization can
be set to any desired direction and the magnitude and direction of the
polarization of the scattered beam determined. The polarimeter exploi
ts the Meissner effect to separate the magnetic fields of the active e
lements. A precision of ca. 2-degrees in the polarization direction ca
n be obtained with the prototype. Expressions are given for the change
in polarization to be expected in diffraction experiments on various
types of magnetic structure and the effect of magnetic domains is disc
ussed. Some examples of the application of the technique to magnetic s
tructure determination are given. Effects due to breakdown of the kine
matical approximation have been demonstrated. Some ideas for a second
generation polarimeter are outlined and new areas of application propo
sed.