Inverse scattering, or the inverse scattering problem, is the problem of determining the characteristics of an object (its shape, internal constitution, etc.) from measurement data of radiation or particles scattered from the object.
It is the inverse problem to the direct scattering problem, which is determining the distribution of scattered radiation/particle flux basing on the characteristics of the scatterer.
Since its early statement for radiolocation, the problem has found vast number of applications, such as echolocation, geophysical survey, nondestructive testing, medical imaging, quantum field theory, to name just a few.