Daniel Courjon

External and internal reflection near field microscopy: experiments and results.

Two configurations of a scanning near field optical microscope working in reflection are presented. Results exhibiting nanometric resolution are given and discussed.

General principles of scanning tunneling optical microscopy

A homogeneous propagating wave falling onto submicrometer objects is partially diffracted into evanescent waves. The use of a scattering probe of subwavelength size can convert the evanescent waves into homogeneous ones and make their detection possible. The resulting propagating waves can then provide information about the subwavelength object. Relations with preliminary experiments are discussed.

Detection of nonradiative fields in light of the Heisenberg uncertainty principle and the Rayleigh criterion

The new concept of superresolution microscopy involving nonradiative field detection by optical tunneling is analyzed in light of the Heisenberg principle and the Rayleigh criterion. A connection is demonstrated between the evanescent field components and the systems resolving power. This work is quite general and can be applied to scanning electronic tunneling microscopy.

Imaging of submicron index variations by scanning optical tunneling

The scanning tunneling optical microscope (SNOM, STOM, PSTM, etc.) is the equivalent of the electron scanning tunneling microscope in the electromagnetic domain. Although it was born at the same time, its actual development is more recent. Here, some new results obtained with the version working in total reflection (STOM/PSTM) are reported. A grating of a periodicity of 417 nm and a thickness of 5 nm have been imaged both in TM and TE modes. It is first noted that the optical image is well resolved. Furthermore, the difference of behavior of the field versus the polarization of the incident light has been shown. More precisely, the TM mode seems to be highly sensitive to small index and topography variations due to surface contaminants. Such effects are generally not imaged by atomic force microscopy working in attractive mode, because they affect the surface topography slightly. The SNOM could be thus a very powerful tool for detecting pollutants over the surface of objects like glasses, lenses, gratings...

HUYGENS-FRESNEL PRINCIPLE IN THE NEAR FIELD

The Huygens-Fresnel principle provides a conceptual understanding for wave propagation and diffraction. Recently the principle has been reexamined to suggest that it is also valid in the near field. We reformulate the problem in terms of nonradiative optics, focusing particularly on the obliquity factor inherent in the forward-directed propagation of light. In the near field of matter no explicit obliquity factor exists.

Comparison of test images obtained from various configurations of scanning near-field optical microscopes

The characteristics of a few experimental near-field optical microscopes, located in different laboratories, have been compared on the basis of their ability to image a well-defined submicrometer test object.

Simplifications of the bilinear transfer for microscopic binary objects

Microscopy of binary objects in partially coherent light is analyzed in terms of bilinear transfer. A transfer model using two apparent transfer functions is proposed. Its domain of validity is studied by numerical simulation.

Evanescent interferometry by scanning optical tunneling detection

The work reported deals with evanescent-wave interferometry. In a scanning tunneling optical microscope (STOM/PSTM) we study the interaction of an evanescent standing wave with nanometer-sized objects. Two complementary numerical models are compared with experimental results. Finally, it is shown that synthetic interferograms can be generated by use of the distinctive features of this kind of microscope.

Near-field probing control of optical propagation in bidimensional guiding mesostructures

Scanning near-field optical microscopy is used for analyzing both the interaction of light with mesostructures and the capability of wave transfer between two macrowaveguides coupled by a matrix of periodic mesostructures. A spectral analysis shows the influence of the wavelength in such a configuration.

Inductive forces generated by evanescent light fields: application to local probe microscopy

Abstract This paper deals with induction of forces by evanescent light fields. Similar to light pressure, such a force field could be substituted for photon detection in near field optical microscopy.