  A forward model is presented to an inverse scattering problem that arises in
the application of reflective Fourier ptychographic microscopy. The model
allows us to determine the 3D distributions of refractive index for weakly
scattering semi-transparent objects using Fourier ptychographic tomography. The
derivation results show that both transmission types reported previously and
reflective type present in this article are corresponding to a specific
application in Wolf's work (Emil Wolf, Opt. Commun. 1969 1(4) pp. 153-156). The
transmission type measures the forward scattering field while the reflective
type measures the backward scattering field. This model is also available for
holographic method
