  R Aqr is a symbiotic binary system consisting of a mira variable, a hot
companion with a spectacular jet outflow, and an extended emission line nebula.
We have used R Aqr as test target for the visual camera subsystem ZIMPOL, which
is part of the new extreme adaptive optics (AO) instrument SPHERE at the Very
Large Telescope (VLT).
  We compare our observations with data from the Hubble Space Telescope (HST)
and illustrate the complementarity of the two instruments. We determine from
the Halpha emission the position, size, geometric structure, and line fluxes of
the jet source and the clouds in the innermost region (<2") of R Aqr and
determine Halpha emissivities mean density, mass, recombination time scale, and
other cloud parameters.
  Our data resolve for the first time the R Aqr binary and we measure for the
jet source a relative position 46+/-1 mas West of the mira. The central jet
source is the strongest Halpha component. North east and south west from the
central source there are many clouds with very diverse structures. We see in
the SW a string of bright clouds arranged in a zig-zag pattern and, further
out, more extended bubbles. In the N and NE we see a bright, very elongated
filamentary structure and faint perpendicular "wisps" further out. Some jet
clouds are also detected in the ZIMPOL [OI] and He I filters, as well as in the
HST line filters for Halpha, [OIII], [NII], and [OI]. We determine jet cloud
parameters and find a very well defined anti-correlation between cloud density
and distance to the central binary. Future Halpha observations will provide the
orientation of the orbital plane of the binary and allow detailed
hydrodynamical investigations of this jet outflow and its interaction with the
wind of the red giant companion.
