  The Crab nebula and its pulsar have been observed for about 3 hours with the
high-speed photo-polarimeter OPTIMA in January 2002 at the Calar Alto 3.5m
telescope. The Crab pulsar intensity and polarization are determined at all
phases of rotation with higher statistical accuracy than ever. Therefore, we
were able to separate the so-called 'off-pulse' phase emission (with an
intensity of about 1.2% compared to the main peak, assumed to be present at all
phases) from the pulsed emission and show the 'net' polarization of the pulsed
structures. Recent theoretical results indicate that the measured optical
polarization of the Crab pulsar is similar to expectations from a two-pole
caustic emission model or a striped pulsar wind model.
