  Coherent pion photoproduction, $d(\gamma,\pi^0)d$, is calculated in a coupled
channels approach in momentum space using an elementary production operator
that includes Born terms, vector meson exchange and $M1/E2$ $\Delta$-resonance
excitation. The final state interaction is treated in the KMT multiple
scattering approach that describes $\pi d$ elastic scattering well.
Differential cross sections are found to agree well with existing ($\gamma,
\pi^0$) data. The polarization observables $\Sigma , iT_{11}$ and the tensor
analyzing powers are predicted for forthcoming experiments. A number of
transparent relationships between polarization observables and the elementary
production operator is derived. Finally, calculations are performed for
coherent eta photoproduction, $d (\gamma, \eta)d$, in the threshold region
which agree well with a very recent Mainz experiment.
