  We present an approach to classical polarimetry that requires no moving
parts, is compact and robust, and that encodes the complete polarization
information on a single data frame, accomplished by replacing the rotation of
components such as wave plates with position along a spatial axis. We
demonstrate the concept with a polarimeter having a quarter wave plate whose
fast axis direction changes with location along one axis of a 2D data frame in
conjunction with a fixed-direction polarization analyzer, analogous to a
classical rotating quarter wave plate polarimeter. The full set of Stokes
parameters is obtained, with maximal sensitivity to circular polarization
Stokes V if a quarter wave retarder is used. Linear and circular polarization
terms are encoded with spatial carrier frequencies that differ by a factor two,
which minimizes cross-talk. Other rotating component polarimeters lend
themselves to the approach. Since the polarization modulation spatial
frequencies do not change greatly, if at all, with wavelength such devices are
close to achromatic, simplifying instrument design. Since the polarimetric
information is acquired in a single observation, rapidly varying, transient and
moving targets are accessible, loss of precision due to sequential data
acquisition is avoided, and moving parts are not required.
