  The QCD coupling appears in the perturbative expansion of the current-current
two-point (vacuum polarization) function. Any lattice calculation of vacuum
polarization is plagued by several competing non-perturbative effects at small
momenta and by discretization errors at large momenta. We work in an
intermediate region, computing the vacuum polarization for many off-axis
momentum directions on the lattice. Having many momentum directions provides a
way to monitor and account for lattice artifacts. Our results are competitive
with, and have certain systematic advantages over, the alternate
phenomenological determination of the strong coupling from the same light quark
vacuum polarization produced by sum rule analyses of hadronic tau decay data.
