Computed imaging for the near-field

A method is presented to reconstruct the structure of a scattering object from data acquired with a photon scanning tunneling microscope (PSTM). The data may be understood to form a near-field hologram of the Gabor type. Data are obtained at a distance from the sample where the field is defocused and normally undecipherable. Object structure is obtained by solution of the linearized inverse scattering problem. The method is demonstrated using a thin gold-on-glass sample, probed by light of wavelength 633 nm, with data taken at probe heights of 100 nm and 200 nm.