  We consider the fixed angle inverse scattering problem and show that a
compactly supported potential is uniquely determined by its scattering
amplitude for two opposite fixed angles. We also show that almost symmetric or
horizontally controlled potentials are uniquely determined by their fixed angle
scattering data. This is done by establishing an equivalence between the
frequency domain and the time domain formulations of the problem, and by
solving the time domain problem by extending the methods of [RS19] which adapts
the ideas introduced in [BK81] and [IY01] on the use of Carleman estimates for
inverse problems.
