Diffraction tomography in the Fresnel zone

Tomographic refractive-index reconstruction is considered with allowance for weak refraction and diffraction effects within the framework of wave-theory approximations: the smooth-perturbation method and the Born approximation. The Fresnel small-angle approximation is used to obtain a comparatively simple algorithms for processing the field and reducing the diffraction-tomography treatment to traditional tomographic reconstruction from linear integrals.