We provide a theoretical study of the near-field optical image of a homogeneous dielectric surface with deterministic sub-wavelength structures. Numerical simulations for different shapes of the sample are performed at constant-height mode with normal incidence. Near-field polarization states have been calculated by analyzing the difference of the transmitted intensities of p- and s-polarized light. We show that the near-field intensity depends more stronger on the feature form than the feature size. However, the polarization property is more sensitive to the shape of the sample rather than the distance of detection.