Reflectors in wave equation imaging

We consider the problem of imaging with the wave equation from backscatter. It is well known that the velocity can be recovered from multi-static measurements provided the source signature has zero frequencies. We show that in the presence of a plane reflector zero frequencies are not needed. The analysis is done within the Born approximation. We show by numerical simulations that this also holds in the fully nonlinear case, even for arbitrarily shaped and unknown reflectors.