  Phase retrieval problems occur in a wide range of applications in physics and
engineering. Usually, these problems consist in the recovery of an unknown
signal from the magnitudes of its Fourier transform. In some applications,
however, the given intensity arises from a different transformation such as the
Fresnel or fractional Fourier transform. More generally, we here consider the
phase retrieval of an unknown signal from the magnitudes of an arbitrary linear
canonical transform. Using the close relation between the Fourier and the
linear canonical transform, we investigate the arising ambiguities of these
phase retrieval problems and transfer the well-known characterizations of the
solution sets from the classical Fourier phase retrieval problem to the new
setting.
