Claudine Bainier

D.C. scanning thermal microscopy : Characterisation and interpretation of the measurement

Abstract The used Scanning Thermal Microscopy (SThM) probe is a thin Pt resistance wire acting as a heat source and as a detector simultaneously. Its energetic balance is investigated by the study of the temperature profile along the probe. A theoretical approach of the measurement, based on this investigation, is then proposed. Simulations with this modelling are shown to predict how the heat, electrically produced in the probe, is dissipated in the probe-sample system. In particular, it is shown that the steady-state of conduction losses to the thermal element support varies versus the thermal conductivity of the sample and can lead to bad interpretations of the measurement.

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...

Seeing inside a Fabry-Pérot resonator by means of a scanning tunneling optical microscope

Abstract By integrating a scanning tunneling optical microscope inside a Fabry-Perot resonator, it is possible to map very precisely the structure of the electromagnetic field inside the resonant cavity. Moreover, by working in antiresonant mode (dark field conditions), it is possible to locally remove the incident evanescent field. This particular configuration increases the z -resolution in such microscopes.

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.

Solar concentrating systems using holographic lenses

Abstract The work presented in this paper deals with the study and the realization of holographic concentrators turning the dispersion of hologram to account in order to adapt the spectral distribution of the photovoltaic cells to the solar spectrum. Two models are presented, working in transmission and in reflection respectively. Various parameters are analyzed and an energy balance is drawn up.

Shaping the reflection near-field optical probe: finite domain time difference modelling and fabrication using a focused ion beam.

An optical fibre ending in a trihedral tip is proposed as a convenient probe for reflection near‐field optical microscopy in emission/collection mode. Its shape is obtained by ion milling. A first example of manufacturing and numerical models using the bi‐dimensional FDTD method is presented. It confirms the strong influence of the facet angle on the intensity reflected by the probe, which is predicted by a rough analysis. This method can help us to optimize the ‘reflection probe’ by reducing this offset signal.

Easy-to-use unglued tip replacement near-field optical microscope with piezoelectric shear force detection

A new nonoptical shear force detection for scanning near-field optical microscopes is proposed in this article. Its main characteristic is a simple and fast tip replacement. The probe is mechanically in contact with a piezoelectric plate of a homemade tuning fork, ensuring a direct coupling and avoiding the fiber tip gluing.

Isotropic incoherent scanning tunneling optical microscope (I2STOM)

Abstract A symmetric illumination device for scanning tunneling optical microscopy is proposed. This new configuration limits the spurious effects due to non isotropic illumination, coherence and polarization effects. Some specific test objects have been fabricated in order to estimate the validity of such a microscope. Experimental results exhibiting highly confined features for a 15 nm chromium layer with 130–150 nm diameter holes have been obtained.

Near-field phase measurement by Fourier analysis of the fringe pattern

As for any electromagnetic field the optical near field in the vicinity of an object is fully described by its amplitude and its phase. However, despite the interest in extracting the information contained in the phase variations, until now mainly the intensity has been investigated. In this paper it will be shown that the phase information can be extracted and measured from the detected intensity, by using in the near-field regime techniques developed in conventional far-field interferometry. It will be shown from experimental and theoretical data that the near-field phase can carry information different from the amplitude.

New optical near field developments: some perspectives in interferometry

Abstract This work deals with the interaction of an evanescent standing wave with nanometer size objects in scanning tunneling optical microscopy (STOM/PSTM). Exploiting both the structure of the fringe pattern perturbed by the object and the last simulation works, we discuss the reality of the near field images. We show that interferometry seems to be a good tool for discriminating the true optical signal from artefacts whose origin is not always understood.