We prove that the singularities of a complex valued potential q in the Schrödinger hamiltonian + q can be reconstructed from the linear Born approximation for full scattering data by averaging in the extra variables. We prove that, with this procedure, the accuracy in the reconstruction improves the previously known accuracy obtained from fixed angle or backscattering data. In particular, for q ∈ W α,2 for α ≥ 0, in 2D we recover the main singularity of q with an accuracy of one derivative; in 3D the accuracy is > 1/2, increasing with α. This gives a mathematical basis for diffraction tomography. The proof is based on some new estimates for multidimensional bilinear Fourier multipliers of independent interest.