  This letter is the first to report that a super-resolution imaging beyond the
Rayleigh limit can be achieved by using classical diffraction tomography (DT)
extended with orbital angular momentum (OAM), termed as OAM based diffraction
tomography (OAM-DT). It is well accepted that the orbital angular momentum
(OAM) provides additional electromagnetic degrees of freedom. This concept has
been widely applied in science and technology. In this letter we revisit the DT
problem extended with OAM, demonstrate theoretically and numerically that there
is no physical limits on imaging resolution in principle by the OAM-DT. This
super-resolution OAM-DT imaging paradigm, has no requirement for evanescent
fields, subtle focusing lens, complicated post-processing, etc., thus provides
a new approach to realize the wavefield imaging of universal objects with
sub-wavelength resolution.
