  The bipolar reflection nebula OH 231.8+4.2 (OH 0739-14), centred on the Mira
variable star QX Pup, has been mapped at Ks in linear polarization using the
ESO SOFI near-infrared multi-mode instrument. The large scale linear
polarization features agree with previous studies, validating the polarimetric
mode of the instrument. However the high spatial resolution of the polarization
map reveals considerable structure, some of which finds correspondence in the
surface brightness images. The core is crossed by low polarization filaments;
the northern lobe reveals an axial finger and a rim of very high linear
polarization (upto 80%) whilst the southern lobe shows less polarization
contrast. There is a trend in polarization perpendicular to the bipolar axis in
both lobes. The individual linear polarization features most probably arise
from localised dust structures with distinct orientations leading to differing
polarization through single scattering. A single scattering geometric model,
consisting of two lobes of ellipsoidal section and a central dense disk, is
considered which can explain the general features of the intensity and
polarization images.
