  This paper investigates the inverse scattering problems using sampling
methods with near field measurements. The near field measurements appear in two
classical inverse scattering problems: the inverse scattering for obstacles and
the interior inverse scattering for cavities. We propose modified sampling
methods to treat these two classical problems using near field measurements
without making any asymptotic assumptions on the distance between the
measurement surface and the scatterers. We provide theoretical justifications
based on the factorization of the near field operator in both symmetric
factorization case and non-symmetric factorization case. Furthermore, we
introduce a data completion algorithm which allows us to apply the modified
sampling methods to treat the limited-aperture inverse scattering problems.
Finally numerical examples are provided to illustrate the modified sampling
methods with both full- and limited- aperture near field measurements.
