PSTM - AN ALTERNATIVE TO MEASURE LOCAL VARIATION OF OPTICAL INDEX

Scanning Tunneling Optical Microscopes (STOM) or Photon Scanning Tunne ling Microscopes (PSTM) have succeed to image solid surfaces with high lateral resolution. However, experimental and theoretical studies hav e proved that images can be very different versus the actual sample pr ofile. In this paper, we extend a previous model based on a perturbati ve resolution of Maxwell equations, with boundary conditions on a mult ilayer sample, to the case of three-dimensional devices. As an illustr ation, STOM can detect index defects. We show that it is feasible to d istinguish index defects near the surface of the sample and geometric defects of the profile. Three experimental parameters must be taken in to account: the detection distance, the angle of incidence and the pol arization of the light can influence the resolution of the index defec t.