The measurement accuracy in non contact profilometric techniques is generally limited by mechanical vibrations and by
geometrical defaults of the micro-scanning table. In order to free the measurement from these environnemental
perturbations, we describe a novel type of interferometric microscopy based on the well-known Spectroscopic Analysis
of White Light Interferograms (SAWLI). The originality of the presented set-up lies in the fixation of the reference plate
on the inspected object. As reference plate and sample are fixed together, the mechanical vibrations do not affect the
measurements. As a result the potential nanometric accuracy of interferometric microscopy is effective. This method
consists in measuring the air gap thickness between the reference plate and the sample. At the output of the spectral
interferometric microscope a channelled spectrum is observed. From this signal, the spectral phase is calculated using a
numerical seven points phase shifting algorithm allowing the measurement of the local height of the analyzed surface.
These preliminary results demonstrate the ability of this method as a point sensor. Then this technique will be
implemented in a high frequency scanning STIL technology named MPLS 180.
In this paper we describe an interferometric process using a polychromatic light source and a spectroscopic detection system. This method is used for surface metrology or for bulk optical components characterisation (dispersion for example). As classical monochromatic interferometry, it consists in comparing a reference wave front with one issued from the component to be tested. However this measurement is assumed by determination of the spectral dispersion induced upon the various frequencies of the light source spectrum. The aim of this work is both dispersion measurements and characterisation of aspherical surfaces
Optical Coherent Tomography (OCT) technique is based on an interferometric device bringing to the inter-correlation between a short reference pulse and the signal issued from the medium. This correlation is obtained by mechanical length modulation of the interferometer reference arm. We propose here an original technique using the SISAM (“Spectroscope Interferentiel a Selection par l’Amplitude de la Modulation”: Interferential Spectrometer by Selection of Amplitude Modulation) correlator, which allows to obtain directly without length modulation, the inter-correlation signal between the reference and the tests waves. With a large spectral bandwidth light source, the temporal depth of the original pulse is short compared to the signal diffused in the complex medium, and the inter-correlation function may be reduced to the impulse response of the structure to be studied. This temporal analysis could be very interesting to obtain both amplitude and phase parameters on the waves propagated in the medium, and could induce significant data on the medium and its structure. We will present the experimental SISAM device and results obtained in imaging through turbid media with this technique. We will also discuss about efficiency of this method in terms of accuracy and of ability to characterize complex structures and media.