Nanostructures imaging via numerical solution of a 3-d inverse scattering problem without the phase information

Inverse scattering problems without the phase information arise in imaging of nanostructures whose sizes are hundreds of nanometers as well as in imaging of biological cells. The governing equation is the 3-d generalized Helmholtz equation with the unknown coefficient, which represents the spatially distributed dielectric constant. It is assumed that only the modulus of the complex valued wave field is measured on a frequency range. The phase is not measured. Two rigorous numerical methods are tested and their performances are compared for realistic ranges of parameters.