Theoretical treatment for scattering scanning near-field optical microscopy

A scanning probe interacts with the optical near field near a sample surface. The whole system radiates, and the radiation is collected in the far field domain. The collected far field contains subwavelength information about the sample surface. A microscopic description of the device is presented. A self-consistent procedure is employed that takes into account the optical coupling effects between the microscopic objects in the probe-surface system to calculate the induced field at the probe and at the surface microscopic features. The radiation stemming from the system can then be described in the half-space. The intensity of the field radiation at the entrance of the far-field detector determines the received signals. Two incident fields, total internal reflection and external reflection, are examined numerically. Subwavelength resolutions of the device are clearly shown. The results are used to discuss other relevant aspects: the resolution of the device, the position of the far-field detector, and the probe material. (C) 1997 Optical Society of America.