Quantitative analysis of apertureless THz scanning near field optical microscopy based on an exact line dipole image method

Summary form only given. We present the line dipole image method which is based on an analytic image theory. The probe tip on the sample substrate is approximated by a metallic sphere for calculation. Within the quasi-electrostatic limit, the exact image theory was iteratively applied to obtain the total induced dipole moment for the sample-substrate system. The experimental approach curves are explained. The measurements of approach curves on gold and silicon substrates were in excellent agreement with the line dipole calculations.