  We study the Josephson effect in a clean
Superconductor-Ferromagnet-Superconductor junction for arbitrarily large spin
polarizations. The Andreev reflection at a clean Ferromagnet-Superconductor
interface is incomplete, and Andreev channels with a large incidence angle are
progressively suppressed with increasing exchange energy. As a result, the
critical current exhibits oscillations as a function of the exchange energy and
of the length of the ferromagnet and has a temperature dependence which
deviates from the one predicted by the quasiclassical theory.
